Rebuilt F3 Shock - Wrist Twisters
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post #1 of 72 Old 02-29-2016, 04:53 AM Thread Starter
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Rebuilt F3 Shock

Yep, so I did it. I rebuilt a 1998 CBR600F3 shock with new internals and spring, and stuck it on my 2007 Honda 919. It's great. Here's the whole saga in short version and long:

SHORT:

Doing all the work myself, I rebuilt an F3 shock with new internals, new spring, and new fluid. I installed it on my 919, and now know what mcromo means when he says "nothing short of transformational". It's a new bike. It handles well, rides well, feels great.
For the parts list, scroll to the bottom.

LONG:

Like pretty much all the rest of you, I bought a 919 last year because
1) I love motorcycles
2) Its looks
3) Its supposed driveability
4) Its price
5) I like to tinker with stuff, and the 919 seemed a good blend of technology (no fucking carbs) and simplicity (no fucking traction control).

Pretty much from day one, I was dissatisfied with the bike. I wanted something with good driveable torque, but nimble handling. My 919 had the first point in gobs, but the second was so lacking that it made the thing all but irritating to ride. It didn't help that the previous owner had ruined the tires (when I bought it the tires were <20psi) and the suspension setup was totally wacky.
Last year I installed RaceTech fork springs (1.0kg/mm for my 6'6", 220 pound self), low flat handlebars, and new tires (Pilot Power 3). These things helped the handling situation, but things were far from ideal. Hell, they were barely acceptable. I put 3,000 miles on the bike, all the time feeling like I'd bought the wrong bike. Woe was me.
I played with the setup of the bike weekly. I used a lot of the info on offer here on WT, was pleasantly guided along by a number of folks (shout out to mcromo in particular!), and took copious notes in my handy-dandy composition notebook.
Despite repeated attempts to square away the bike, the handling was just atrocious. It was unnerving to push hard, unsettling to ride on rough roads, and gave absolutely no sense of confidence. I loved my motorcycle, but it sucked. Think parenthood.

As we all well know, the shock seems to be the root of all evil on the 919s. I was hesitant to put any dough into the shock, knowing that if it didn't fix my problems, I was probably going to sell the bike anyway come spring. I pondered on it a bit, and last fall figured I kinda owed it to myself and my bike to give the shock a good try.

Being a 919 owner (and thus a broke-ass), I wasn't able/willing to a spend a bunch on a fancy Ohlins or Penske shock. I had seen the posts on here about using an F3 shock (mtnniceguy and a couple others sorta paved the way here. Nice work, fellas.). I liked the notion of the cheap shock, but I also recognized that the stock internals that were designed 20 years ago for a linkaged sport bike were not appropriate for the 919. Even though I wasn't going to spend the dough on a big name, I definitely wanted my shock to at least be valved correctly. Also, I knew that any shock I picked up would likely be in desperate need of a rebuild simply from sitting God knows where for the last two decades. Together, that spelled P-R-O-J-E-C-T to me.

I got in touch with RaceTech about their Gold Valve for the F3 shock I got off eBay. It sounded like they would need a lot of input and whatnot from me to build a special piston/stack combo for the F3 that would make it appropriate for the 919. That didn't sound like fun to me. If I was going to be the development monkey, I sure as hell wasn't going to pay them for the opportunity. With that in mind, I determined to make my own shim stack and piston modifications.
From here, it was research time. I researched linkages, ratios, valving, shims, rebound, compression, pistons, tuning, fluids, blah blah blah. I went nuts. I spent half my spare time on Borynack and Verdone's sites, and the other half on WT and IBSF. I learned a shit-ton about shocks and valving and whatnot. Mostly I learned that I don't have nearly the experience nor the expertise to properly develop a good valving setup for my bike from scratch. I might (MIGHT!) be able to squeeze into the ballpark, but it wouldn't be right and I would never be confident that I was getting out of the new-to-me shock what could be got.
With all of my internet stumbling and "research"ing, I ended up in contact with a pretty well-regarded one-man company who does a lot of tuning and rebuilding of shocks for Hondas like ours. He doesn't specialize in 919s, but he's worked with them and has done lots of work with very similar shocks/bikes/problems. He sold me a new piston of his own design/production with a shim stack developed for the 919. Just like that, I saved myself a crap ton of time and energy, and got an excellent product that gave a high degree of confidence in the eventual result. Bingo. This, my friends, was the right way to do it.

Once I had the valving and had received a new spring and Schrader valve for the re-charging of nitrogen, it was just a matter of reviewing and re-reviewing the methods for assembly/bleeding of the shock, and the procedure for installing the thing on my bike.
The step-by-step directions for the disassembly/reassembly of the shock are readily available elsewhere, so I won't go into the details. For all you guys who think it's complicated: it ain't. It's a pretty simple process (just follow the directions!), and as long as one takes ones time, pays attention, and ensures the methods being used are what's recommended, there's not a lot to go wrong. I have a little 10'x12' basement shop that I use for all my projects; home improvement, motorcycle, bicycle, etc. My handiness is mid-level, and I'm definitely not one of those types who seem to be able to work magic with their hands. I have to focus carefully and really ensure I do things well/right and don't get ahead of myself or impatient. In other words, though I've always liked tinkering with stuff and have some experience behind a wrench, I'm not a natural engineer. So if I can do it, you probably can too.
I used a homebuilt spring compressor (the threaded rod/bar stock type), a bench vise w/ padded jaws, a drill press, a torque wrench, a thread tap that I bought for this project, and the usual hand tools that every Real Man probably has multiples of. I also wore safety glasses the ENTIRE time I was fooling with this stuff, and often made use of a rubber apron to keep my filthy shop clothes from getting soaked through with shock fluid. With the exception of the drill press (a hand drill would have been fine), I don't think I could have done without any of these tools. I tried several automotive spring compressors, and none of them fit. Thus the decision to just make one. It worked out totally fine.
I took the shock to my local moto shop/suspension guys to get charged with nitrogen through the Schrader valve I installed. No problems here.

The install onto the bike was equally easy. I hung my bike from the rafters, and used the method outlined by mcromo in post #18 of this thread: https://www.wristtwisters.com/forums/...ild-32389.html
I did take a bit of time to position the way-too-long reservoir hose so it wouldn't kink and to secure the new reservoir in a position that will allow easy access to the compression adjustments.

I set sag as outlined in the Sportbike Rider articles. Setting Static Sag | Sport Rider


I wasn't able to ride the bike for a few days after the install/completion. I was pretty excited/nervous to see how the thing would do. When I finally got to put in a couple days of solid riding, all my fears were quickly put to rest. This shock has absolutely transformed my motorcycle.
Handling: It handles turns very predictably, including my special "testing" turn that has a huge pavement lip across the entire two lanes right after the apex of the turn. In the past, this has unsettled the bike to a scary degree; now it's not a biggie. The bike "tips" in quickly and controllably. Changing lines in the turn is now much less of a challenge. Accelerating hard out of the turn is now actually a possibility that doesn't strike a bolt of fear straight through my heart.
Accelerating: The bike feels like a rocket; it fires straight forward. No more of that "squish, wiggle, squat" with vagueness in the rear. No more "God- am I pulling a little wheelie, falling off the back, or just pulling away from a stoplight?!" It's fantastic.
Road Feel: Speedbumps and rough pavement are still there, but the bike now takes them on with grace. Gone are the butt-tossing hops and spine-chilling shakes over little bumps or potholes.
Adjustments: Yes, the compression and rebound adjustments work. I've been playing with them, and have a reasonable setting at 1/2 turn in on rebound and 3/4 turn in on compression. I'm sure this will change. Almost as exciting is that the spring preload adjuster on the F3 shock is on the BOTTOM of the mounted shock, thus allowing extremely easy access with the spanner. Like crazy-easy access. I can't fathom why the original shock had it on top. What a PITA.

In short, this project was fun, rewarding, inexpensive, and extremely effective.


Here are the prices/details on most of the parts:

- Used 1998 F3 shock. $35 shipped on eBay

- New piston/shims and main seal. $142 shipped from a known specialist

- Eibach 600.225.1100 spring. $73 shipped from ultrarev.com This is 6"long x 2.25" I.D. x 1100 lbs/in. (( Contrary to a couple things I read, no grinding was required. It fit like a glove. ))

- Schrader valve with 1/8" NPT threading. $7/pair on Amazon.

- Silkolene RSF Pro 5wt shock fluid. $23 from local shop.

Total: $274 for parts. Also spent $6 on the thread tap tool and $11 on welding bar stock, nuts, and washers for the spring compressor.

Here are some links to sites I used for research and guides for disassembly and reassembly and shock selection:

- The site you're on.
- Peter Verdone's site.
- Borynack's guide.
- The IBSF
-
- mcromo's install guide
- jnich77's thread

- I also spent a lot of time on forum sites devoted to other inadequate Hondas. VTRs, Hawks, old CBRs, etc.

I hope this helps anyone who's interested in undertaking this project themselves.

-B
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post #2 of 72 Old 02-29-2016, 06:22 AM
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Excellent work! I started down a similar path a couple years ago, but with the forks. Eventually came to a similar conclusion regarding any attempt to build my own stacks. After that, I gave up on thoughts of doing the shock myself, and bought one instead. I'm glad to see you persevered! There's a great feeling of satisfaction in succeeding with a project like this.

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post #3 of 72 Old 02-29-2016, 09:40 AM
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Good work, dude, both in the rebuilding adventure, and in the write-up. And in adding to the body of knowledge about shocks and 9'ers. Thumbs up!!

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post #4 of 72 Old 02-29-2016, 02:29 PM
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Really nice write up in terms of breadth, detail and approach.
I'm curious about your rear setup in terms of the Free and Rider Sag values you have settled upon so far.
The aforementioned being asked while also keeping in mind the longer free length of the F3 shock's eye to eye distance.
One major reason your stated tip in is easier, is due to your bikes C of G having been elevated by your changes.
Your front will also be riding higher do to the 1.0 springs.
I won't guess if your fore and aft lifts are the same, if I had to guess, I'd say your rear has likely been lifted more than the front, that said assuming you have not raised the tubes in the clamps (don't!) and you have something like 35 mm of Rider Sag at the Front.

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post #5 of 72 Old 02-29-2016, 03:46 PM Thread Starter
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Thanks fellas. Glad you appreciate it.

mcromo: I set my sag by fully extending the rear end (hung the bike) and measured from one of my wheel bolts to a bolt on my Yoshi pipe. Full extension was 21 7/8". Sitting on the bike after rocking the stiction out, the distance between the same two points was 21" exactly. That's 7/8" or 22mm of sag. The 1100lb spring is on the 3rd notch for preload.

Re: Lift. Now that the changes have been made, how would I go about confirming the amount of lift on each end?

The extra spring and eye-to-eye has definitely given the rear end more height. I can see it and feel it. I did leave my forks drawn up by 10mm in the triple; didn't want to change everything at once. Feels okay now. . . Maybe it's just that anything feels better after what I had.
I'm considering double-checking my installed preload and going from 140mm to 130mm of oil in the forks in the next week or so anyway.


Thanks,
B

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post #6 of 72 Old 02-29-2016, 04:05 PM
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Quote:
Originally Posted by brushbuster View Post
Thanks fellas. Glad you appreciate it.

mcromo: I set my sag by fully extending the rear end (hung the bike) and measured from one of my wheel bolts to a bolt on my Yoshi pipe. Full extension was 21 7/8". Sitting on the bike after rocking the stiction out, the distance between the same two points was 21" exactly. That's 7/8" or 22mm of sag. The 1100lb spring is on the 3rd notch for preload.

Re: Lift. Now that the changes have been made, how would I go about confirming the amount of lift on each end?

The extra spring and eye-to-eye has definitely given the rear end more height. I can see it and feel it. I did leave my forks drawn up by 10mm in the triple; didn't want to change everything at once. Feels okay now. . . Maybe it's just that anything feels better after what I had.
I'm considering double-checking my installed preload and going from 140mm to 130mm of oil in the forks in the next week or so anyway.


Thanks,
B
1
22 mm of rider sag by a 1100 # spring is way too little.
I'll bet you have no more than 3 mm of Free Sag.
I suggest you back off the preload.

2
Your raised back end also changes the swing arm angle and gives more Anti Squat.
So you are getting gains in Anti Squat by more swing arm angle and stiffer shock.
If you have more low speed compression damping force now, you get even more Anti Squat by that.
Swing arm angle is a major issue on 919s as stock they are quite flat, and 919s have much torque and lots of torque multiplication by virtue of the bike being geared for a lower top speed as compared to a properly faired super sport of similar power.

3
Good idea to double check the front spring installed preload.
Seeing as you have 1.0s I'd suggest max 10 mm of installed preload and later trying 5 mm as well.
125 mm of oil level is a pretty standard number for softer sprung bikes.
For 1.0s it would be interesting to see if you end up liking 140 better than 125/130.

4
I suggest you try dropping the tubes back down, to the point of the fork caps being flush with the top of the triple clamp.
10 mm of raise is extreme in concert with the revised rear end.
My guess is that you'll have lost MMs of trail.
Which is less than not desireable.

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post #7 of 72 Old 03-19-2016, 07:06 AM Thread Starter
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Aha. So, I've done some fooling with the forks and I double checked my sag numbers and whatnot.

I cracked open the forks and re-checked my preload. I guess I'd used the wrong method last time, because after careful checking, I found I only had 2mm (yes- two) of installed preload. I went ahead and set it up for 15mm of IP this time. Figure I'd rather start high and work down. Also went with 125mm oil level.
With the RH adjusters backed all the way out, I now have 21mm free sag and 33mm rider sag. After riding every day for the last week, my fork travel zip tie is 26mm below my "true bottom" tape.

The shock sag has also been adjusted. With the preload on level "2", I have 9mm of free sag and 35mm of rider sag. Seems reasonable.

Oh, and raised the triples up the tubes so that the bottom of the blue cap is even with the level of the triple.

The bike still feels great. It's not *quite* as tippy into the turns, but it's way way more stable through them and picks up really easily on the way out. Also, I had a couple front wiggle moments during hard acceleration or wheel-lofts before raising the triples up the tubes- that seems to be gone now.
Also, mid-corner bumps introduce absolutely no wobble/float. I've got the rebound on both shock and fork at almost full hard, and shock compression toward the softer side of things. The compression adjustments I'm not sure I can feel, but the rebound turns have made a huge difference. The improvement in the front end non-wobble/float on bumps is super confidence inspiring.
I've always loved the 919's motor. Now I feel the bike is living up to that motor. Overall, pretty happy with the current stage.

One note- at the very bottom of the fork extension, so at parking lot speeds, I feel like there's something bumping around in the fork- particularly under light braking. Maybe it's just getting extended too hard with the heavy 1.0 springs and all the preload? I've checked all my bolts and whatnot, and am absolutely positive the overhaul reassembly was done correctly. I'm thinking steering bearings might need a check.

So now I'm at the "what now?" stage. I feel like the 1.0s are such a departure from the stock springs, surely the valving needs to be tinkered with. I'm considering a GV for compression and rebound. But then I wonder if a full kit from Daugherty or someone would be more effective; proper spring weight paired with proper valving and whatnot. Oh, motorcycles are such a joy to the heart and drain on the wallet.

-B

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post #8 of 72 Old 03-19-2016, 01:15 PM
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Quote:
Originally Posted by brushbuster View Post
Aha. So, I've done some fooling with the forks and I double checked my sag numbers and whatnot.

I cracked open the forks and re-checked my preload. I guess I'd used the wrong method last time, because after careful checking, I found I only had 2mm (yes- two) of installed preload. I went ahead and set it up for 15mm of IP this time. Figure I'd rather start high and work down. Also went with 125mm oil level.
With the RH adjusters backed all the way out, I now have 21mm free sag and 33mm rider sag. After riding every day for the last week, my fork travel zip tie is 26mm below my "true bottom" tape.

The shock sag has also been adjusted. With the preload on level "2", I have 9mm of free sag and 35mm of rider sag. Seems reasonable.

Oh, and raised the triples up the tubes so that the bottom of the blue cap is even with the level of the triple.

The bike still feels great. It's not *quite* as tippy into the turns, but it's way way more stable through them and picks up really easily on the way out. Also, I had a couple front wiggle moments during hard acceleration or wheel-lofts before raising the triples up the tubes- that seems to be gone now.
Also, mid-corner bumps introduce absolutely no wobble/float. I've got the rebound on both shock and fork at almost full hard, and shock compression toward the softer side of things. The compression adjustments I'm not sure I can feel, but the rebound turns have made a huge difference. The improvement in the front end non-wobble/float on bumps is super confidence inspiring.
I've always loved the 919's motor. Now I feel the bike is living up to that motor. Overall, pretty happy with the current stage.

One note- at the very bottom of the fork extension, so at parking lot speeds, I feel like there's something bumping around in the fork- particularly under light braking. Maybe it's just getting extended too hard with the heavy 1.0 springs and all the preload? I've checked all my bolts and whatnot, and am absolutely positive the overhaul reassembly was done correctly. I'm thinking steering bearings might need a check.

So now I'm at the "what now?" stage. I feel like the 1.0s are such a departure from the stock springs, surely the valving needs to be tinkered with. I'm considering a GV for compression and rebound. But then I wonder if a full kit from Daugherty or someone would be more effective; proper spring weight paired with proper valving and whatnot. Oh, motorcycles are such a joy to the heart and drain on the wallet.

-B
GVs are great and I have them in my good bike. But they are not the only way. Suzuki uses the same cart in many models. Pistons from say a Bandit 1200 offer much more flow. So get some valves from them and find a copy of Racetechs valve builds. I used a c33 in one I built with a 1mm hole drilled in the cart body. Easy and cheap.

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post #9 of 72 Old 03-20-2016, 08:38 PM
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Quote:
Originally Posted by brushbuster View Post
Aha. So, I've done some fooling with the forks and I double checked my sag numbers and whatnot.

I cracked open the forks and re-checked my preload. I guess I'd used the wrong method last time, because after careful checking, I found I only had 2mm (yes- two) of installed preload. I went ahead and set it up for 15mm of IP this time. Figure I'd rather start high and work down. Also went with 125mm oil level.
With the RH adjusters backed all the way out, I now have 21mm free sag and 33mm rider sag. After riding every day for the last week, my fork travel zip tie is 26mm below my "true bottom" tape.

The shock sag has also been adjusted. With the preload on level "2", I have 9mm of free sag and 35mm of rider sag. Seems reasonable.

Oh, and raised the triples up the tubes so that the bottom of the blue cap is even with the level of the triple.

The bike still feels great. It's not *quite* as tippy into the turns, but it's way way more stable through them and picks up really easily on the way out. Also, I had a couple front wiggle moments during hard acceleration or wheel-lofts before raising the triples up the tubes- that seems to be gone now.
Also, mid-corner bumps introduce absolutely no wobble/float. I've got the rebound on both shock and fork at almost full hard, and shock compression toward the softer side of things. The compression adjustments I'm not sure I can feel, but the rebound turns have made a huge difference. The improvement in the front end non-wobble/float on bumps is super confidence inspiring.
I've always loved the 919's motor. Now I feel the bike is living up to that motor. Overall, pretty happy with the current stage.

One note- at the very bottom of the fork extension, so at parking lot speeds, I feel like there's something bumping around in the fork- particularly under light braking. Maybe it's just getting extended too hard with the heavy 1.0 springs and all the preload? I've checked all my bolts and whatnot, and am absolutely positive the overhaul reassembly was done correctly. I'm thinking steering bearings might need a check.

So now I'm at the "what now?" stage. I feel like the 1.0s are such a departure from the stock springs, surely the valving needs to be tinkered with. I'm considering a GV for compression and rebound. But then I wonder if a full kit from Daugherty or someone would be more effective; proper spring weight paired with proper valving and whatnot. Oh, motorcycles are such a joy to the heart and drain on the wallet.

-B
Suggest you try the 1.0s with the 15 mm of IP with 140 mm oil level.
Then try 10 mm of IP with the same 140 mm oil level then 125. (try this with all ride height rings showing and then with 2 rings turned in)
Pick what you like best.
The 33 mm rider sag sounds about right for your spring set-up, and is in the zone of desireable.

How hard have you been braking re the 26 mm you are still away from your bottom indication tape?
IF real hard, then you are oversprung near full compression. (rate, IP & oil level combination)

Your rear #2 Preload Position 9mm of free sag and 35mm of rider sag does indeed seem reasonable.
Here too, in the zone of desireable, keeping in mind the longer length of the F3 shock, in other words a bigger Rider Sag number is a good strategy.
Suggest you zip tie the shock shaft to be able to monitor the maximum shaft stroke.
Hopefully you are not bottoming out on the snubber.

By dropping the tubes you’ve got the front and rear chassis heights in a much better relationship, keeping in mind the longer length of the F3 shock.
Oh, and raised the triples up the tubes so that the bottom of the blue cap is even with the level of the triple.

You’re describing much improved handling in every category.
That being the case, I’d expect the bike to want the rear shock with more low speed compression and less rebound.
Is it possible you have it reversed in terms of counting in from full soft as compared to counting out from full hard? Something like that?
Re the front, very suprising to hear you need to have the rebound set near full hard.
How many turns out from full hard are you at?
(I’ve been using 1-3/8ths turns out from full hard with 0.925s / 14 mm IP / Racetech US-1 2.5/5 wt oil)
(my forks have been valved and shimmed and are set up for light oil, but the low speed rebound circuit as controlled by the adjustable needle rod is stock)
What oil weight are you using ?

If you check the steering head bearings, be sure to remove the wheel and the forks, one can not do a proper check or bearing adjustment unless the wheel and forks are removed.

Assuming that 10 wt oil is used, the stiffer springing setup effectively gives you more compression damping force. I’d think the rebound needle would still be in the effective tuneable range.
Revalving and reshimming, as configured for, and used with, lighter oil, will help.
Your total springing is very stiff, anything over 0.95 sounds extreme to me. My guess is that 925 to 95 would be ideal for your particulars and intended use, in the 15 – 10 mm of IP range, with 125 mm of oil level.
Ohlins valves provide some damping force curve shaping.
Racetech and Traxxion don’t, they rely purely on the shim stack. Two different approaches, they both work, and within the confines of modifying 919 OEM forks it won’t matter. What will matter is the tuner’s valve and shimming configuration, in other words, the tuner.

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post #10 of 72 Old 03-21-2016, 07:19 AM
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A bit more on the rear's comp and rebound setting you are using at present.
I went back and read all your details again and caught the info about the special piston and stack build.
My guess is that the builder put in lots of low speed compression damping.
Maybe the low speed rebound circuit is stock, and very weak in comparison to the roughly doubled spring rebound energy it now sees. Just a thought.

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post #11 of 72 Old 03-22-2016, 02:52 PM Thread Starter
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mcromo- as always, thanks for the detailed discussion.

I had a free day in nice weather, so I looked the bike over. Check the steering bearings- they're good to go. Since everything was already off, I went ahead and cracked open the forks again. Went ahead and dumped a bit of oil to go with 140mm per your advice.
On my 30-min ride, I can't really tell any difference as far as the oil goes. I'll be riding all week, so we'll see.

I did find a little teeny bit of road tar stuck to my front right brake rotor, though. It seems that is where that little "knock" at 1-3mph was coming from. Took it off with a razor and cleaned the spot with alcohol. All is well now. Silly.

With regard to your braking/26mm travel question: I'm definitely not a hard braker. I don't really like to hit high speeds on public roads, so I don't end up getting high braking loads. I suspect this may also feed in to your question regarding rebound and compression settings. . .
First off, I've got 10w Motorex fork oil. I seriously doubt I push the bike as hard as a lot of folks on this board, and certainly not as hard as you would your track bike. I wonder if this doesn't lead to my very different "preferred" setting. I use quotes because I'm not saying my setup is right, or even close to the best it can be in its current form, but rather it feels good to me within the pretty unscientific, limited experimentation I've done. Essentially, I ran through a couple bumpy tight turns I hit on a regular basis and turned the adjusters until I didn't get any floaty wobble. I do like playing with the details sometimes, but on a naked streetbike, really I'd rather set it and forget it. More fun in the sun, less fretting the setting.
I now have no floaty wobble, very little acceleration squat, great turn-in, great mid-corner balance, and great picking-the-bike-up-out-of-the-turn. Compared to the bike's stock condition, this thing has improved roughly a thousand percent. It's even easier to modulate the throttle through the turn, 'cause I don't feel like I'm about to get tossed off when I give a little twist. I really can't overemphasize the effect of the new shock. It's insane.
That said, you've not steered me wrong in any of the advice you've given over the last few months. As such, I'm planning on another suspension setting session tomorrow.

-B

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post #12 of 72 Old 03-22-2016, 02:54 PM Thread Starter
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Quote:
Originally Posted by NZspokes View Post
GVs are great and I have them in my good bike. But they are not the only way. Suzuki uses the same cart in many models. Pistons from say a Bandit 1200 offer much more flow. So get some valves from them and find a copy of Racetechs valve builds. I used a c33 in one I built with a 1mm hole drilled in the cart body. Easy and cheap.
NZspokes- how very interesting. How big an effect did you see from this?
Do the Bandit valves have similar port sizes to the RTs?

-B

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post #13 of 72 Old 03-22-2016, 09:02 PM
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Originally Posted by brushbuster View Post
mcromo- as always, thanks for the detailed discussion.

I had a free day in nice weather, so I looked the bike over. Check the steering bearings- they're good to go. Since everything was already off, I went ahead and cracked open the forks again. Went ahead and dumped a bit of oil to go with 140mm per your advice.
On my 30-min ride, I can't really tell any difference as far as the oil goes. I'll be riding all week, so we'll see.

I did find a little teeny bit of road tar stuck to my front right brake rotor, though. It seems that is where that little "knock" at 1-3mph was coming from. Took it off with a razor and cleaned the spot with alcohol. All is well now. Silly.

With regard to your braking/26mm travel question: I'm definitely not a hard braker. I don't really like to hit high speeds on public roads, so I don't end up getting high braking loads. I suspect this may also feed in to your question regarding rebound and compression settings. . .
First off, I've got 10w Motorex fork oil. I seriously doubt I push the bike as hard as a lot of folks on this board, and certainly not as hard as you would your track bike. I wonder if this doesn't lead to my very different "preferred" setting. I use quotes because I'm not saying my setup is right, or even close to the best it can be in its current form, but rather it feels good to me within the pretty unscientific, limited experimentation I've done. Essentially, I ran through a couple bumpy tight turns I hit on a regular basis and turned the adjusters until I didn't get any floaty wobble. I do like playing with the details sometimes, but on a naked streetbike, really I'd rather set it and forget it. More fun in the sun, less fretting the setting.
I now have no floaty wobble, very little acceleration squat, great turn-in, great mid-corner balance, and great picking-the-bike-up-out-of-the-turn. Compared to the bike's stock condition, this thing has improved roughly a thousand percent. It's even easier to modulate the throttle through the turn, 'cause I don't feel like I'm about to get tossed off when I give a little twist. I really can't overemphasize the effect of the new shock. It's insane.
That said, you've not steered me wrong in any of the advice you've given over the last few months. As such, I'm planning on another suspension setting session tomorrow.

-B
The 125 versus 140 oil level really only displays itself near full bump under hard braking.
The idea is some stiffening toward full bump to allow for softer springing in the normal travel for better compliance, in both upright and lean conditions.
Unless one tests towards the extreme of full bump travel, the difference between 125 and 140 is not be detectable, so your not feeling any difference makes perfect sense.

Suggest you pull the pad and see if you have a tar smear line on the friction surface and if so, try to clean it off with something like contact cleaner.

Your 26 mm front end remaining travel makes sense if you are not doing real hard braking.
I suspect you’ve done some firmer braking than you think, as 26 mm remaining is not all that much.

You have 10W oil. Assumed is that it was dearated by slow manual pumping of the rod.
It’s possible to have excessive rebound dialled in and not have it apparent on the street by the kind of feedback you’d get on a track at any kind of pace. Now knowing the oil, the best way to review this is simply to look at how many turns out from full hard you are set at. What setting are you presently at ?
My guess is that your front rebound is in the zone, and perhaps a bit too firm, but not to a problematic degree, otherwise you’d not be enjoying it so much. Your turns count will be insightful here.

Seeing as you have experienced extreme improvements by shock as now set up, the settings have to be nicely in the zone as a function of what the damping force characteristics are for the shock’s hardware as altered by the hydraulic adjustments (aka “settings) you have made.

It’s clear you’ve made great gains in overall handling, and your rational step by step approach is the key.
You have to have it decently sorted to get what you are now getting, and good on you for that.

Set it and forget it for more fun in the sun and less fretting of the setting.
I LUV that one, it’s a keeper – I should post it on my wall to keep me in line!

A well sprung, well damped 919, set up tall front and back, with decent anti-squat, and nicely ridden, behaves as you have described.
I’d love to hear how tomorrow goes for you.
Keep us posted.

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post #14 of 72 Old 03-22-2016, 09:14 PM
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Originally Posted by brushbuster View Post
NZspokes- how very interesting. How big an effect did you see from this?
Do the Bandit valves have similar port sizes to the RTs?

-B
Note NZspokes advice about the 1 mm hole. It's how one dials in some Low Speed Compression function into a fork that has no adjustable Low Speed Compression circuit, such as a 919. You get and un-tunable "some" instead of "none". Mine have the same feature, a drilled hole of a certain size that is. The valve body gets drilled. Per zaq123 on March 14, 2011, he used a #55 Drill (= 0.0520 " dia.) after researching it with some Racetech data. He provided a real nice notated Racetech diagram showing it.

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post #15 of 72 Old 03-23-2016, 02:56 AM
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Originally Posted by brushbuster View Post
NZspokes- how very interesting. How big an effect did you see from this?
Do the Bandit valves have similar port sizes to the RTs?

-B
Very big effect. Problem with the stock 919 setup is the restrictive piston. I believe they use a soft spring with high comp is so it feels good in the showroom.

Bandit piston is not as high flow as a GV but way better than the stock. With the right stack it works well.

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post #16 of 72 Old 03-23-2016, 06:17 AM
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Originally Posted by brushbuster View Post
One note- at the very bottom of the fork extension, so at parking lot speeds, I feel like there's something bumping around in the fork- particularly under light braking. Maybe it's just getting extended too hard with the heavy 1.0 springs and all the preload? I've checked all my bolts and whatnot, and am absolutely positive the overhaul reassembly was done correctly. I'm thinking steering bearings might need a check.
Weird, I had the same issue after reworking my forks... Haven't been able to track it down either

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post #17 of 72 Old 03-23-2016, 06:20 AM Thread Starter
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Weird, I had the same issue after reworking my forks... Haven't been able to track it down either
Check your spacer cuts, too. I had a friend tell me this was his issue. His spacers were cut with a hacksaw as opposed to a pipe cutter. It made things wiggle around a bit. New spacers of the same length and material cut correctly with a pipe cutter solved it for him.

-B

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post #18 of 72 Old 03-23-2016, 06:52 AM
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Originally Posted by brushbuster View Post
Check your spacer cuts, too. I had a friend tell me this was his issue. His spacers were cut with a hacksaw as opposed to a pipe cutter. It made things wiggle around a bit. New spacers of the same length and material cut correctly with a pipe cutter solved it for him.

-B
A pipe cutter or lathe is indeed the best way to do the cutting of spacer stock material.

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post #19 of 72 Old 03-23-2016, 07:30 AM
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Quote:
Originally Posted by brushbuster View Post
Check your spacer cuts, too. I had a friend tell me this was his issue. His spacers were cut with a hacksaw as opposed to a pipe cutter. It made things wiggle around a bit. New spacers of the same length and material cut correctly with a pipe cutter solved it for him.

-B
I used the metal tubing that came with the springs and cut it on a lathe, so I don't think that's the issue.

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post #20 of 72 Old 04-04-2016, 10:18 AM
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Originally Posted by brushbuster View Post
As such, I'm planning on another suspension setting session tomorrow.

-B

How did things turn out during your setting session?

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post #21 of 72 Old 04-04-2016, 06:57 PM Thread Starter
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How did things turn out during your setting session?
mcromo: Thanks for following up! I ended up not being able to do the session that day, as the 5-0 had my favorite road closed down because of an accident.
I did end up doing a short (~30min) session of riding and adjusting- and honestly, I'm not sure I push hard enough to notice a lot of difference. I did end up bringing the fork rebound back (1 1/8 turns) before it started to feel funky over my "bump in the center" turn. It's almost like it felt slightly less "stiff" to a certain point, but too little rebound made it bouncy.
While this info mulled itself over and over in the back of my mind, I had intended to do another full session (3-4 hours) of riding/testing/adjusting, but exciting news has kept me away. Some things have changed for me, and it looks like a Monster 1100 Evo might very well be in my near future. I'm a superstitious SOB, so I've largely parked the Honda so as to limit the potential of a wreck/rear ending/whatever.
If the Duc happens, I'll be selling the 9er. Bittersweet, but seems like an appropriate maneuver.

At any rate, I'm sure some suspension tuning will be happening soon, be it on the 9er or another beast. If the Duc doesn't waddle its way into my pond, I'll have another go at the twisties. . . both the road and the screwdriver.

-B

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post #22 of 72 Old 04-18-2016, 11:05 AM
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Originally Posted by brushbuster View Post
mcromo: Thanks for following up! I ended up not being able to do the session that day, as the 5-0 had my favorite road closed down because of an accident.
I did end up doing a short (~30min) session of riding and adjusting- and honestly, I'm not sure I push hard enough to notice a lot of difference. I did end up bringing the fork rebound back (1 1/8 turns) before it started to feel funky over my "bump in the center" turn. It's almost like it felt slightly less "stiff" to a certain point, but too little rebound made it bouncy.
While this info mulled itself over and over in the back of my mind, I had intended to do another full session (3-4 hours) of riding/testing/adjusting, but exciting news has kept me away. Some things have changed for me, and it looks like a Monster 1100 Evo might very well be in my near future. I'm a superstitious SOB, so I've largely parked the Honda so as to limit the potential of a wreck/rear ending/whatever.
If the Duc happens, I'll be selling the 9er. Bittersweet, but seems like an appropriate maneuver.

At any rate, I'm sure some suspension tuning will be happening soon, be it on the 9er or another beast. If the Duc doesn't waddle its way into my pond, I'll have another go at the twisties. . . both the road and the screwdriver.

-B
Someone will get your nice 9er when you get your Duc.
That sounds good to me !
By the way, for what it's worth re too much rebound :
Track day / good grip conditions but bumpy / 80+ mph turn # 6
Front end, good compliance, push to point of getting some front end "patter" from some front tire "slip-stick" (you can see the evenly distributed slip marks on the sidewall).
Then add 1/8 turn harder preload
After getting tire back up to temp but still at a "just in case reduced pace" ride, front end very wooden, no patter, running wide. Yes, 1/8th of a turn did that.
The reality is that any significant disruptive change in road, should be met by a feeling of the suspension working compliantly to compensate for it, and not like a slot car on a slot car track. Proper suspension movements are what maintain control and grip, and sometimes more is needed than you might imagine.

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post #23 of 72 Old 06-30-2017, 12:03 PM
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piston/shims*

,,any disclosure on modified piston/shims (from a known specialist) used in the project?

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post #24 of 72 Old 07-10-2017, 10:25 AM
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F3 project /takeoff

OK, I went on sc31 shock project path. Was not satisfied with HYPER PRO springs.
-First I bought nitrogen filling eq.; honestly, dont yet know if it will be used at all
-Then I found sc31 shock on ebay. I planed to take it apart and take it to shop to shorten it for 1cm (as you all were sayin that F3 shock 1cm longer than original) After shock delivery, first thing, I used ruler and found that it is direct fit. Lenght (eye to eye) is exactly the same as 919's shock. No disasembly needed (as per shortening).
-I am still waiting for delivery of 6'' 1050lb spring.
-Spring compressors were easy to made)

Plan is to install new 1050# spring and measure(and find) free and rider sag. Than take it for a ride, to determine if shock can handle my requirements. That would be comp. adjustment/vs. none on 919's original, and rebound. If its acceptable I dont think I will fiddle with shock any more(as take apart).
I am a little woried about spring lenght. SC31 shock have 13cm/5in long seat for spring(919's seat is 14,5cm). I am not sure if 6'' spring will fit to sc31/and if it will, what would be free sag then, if any?

I made some pics of 919's spring(15cm long) sc31 shock and spring(14,5cm long).

I need some help on dissasembly of reservoir? do I need to drill a hole into cap? Is there valve under the cap?
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post #25 of 72 Old 07-10-2017, 01:05 PM
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1
Aside from WT'er "brushmaster", the originator of this thread, I don't remember anyone else posting about having actually done the hydraulics work themselves, as compared to going a specialist to have it done for them.
I suggest you try PM'ing him.
Maybe someone else who's actually done similar work will respond.

2
I think the spring is going to be an issue.
Your pictures show the installed spring height on the sc31 is about 13 cm.
And that the installed spring height on the 919 unit is about 15 cm. (valid, my bench 02 shock with nominal 1200 #/in OEM spring measures 14.8 at softest preload setting = installed spring height)
Hmmmm…..
15-13=2 cm difference in installed height.
2/2.54 = 0.787 in.
0.787 X 1050#/in = 826 # installed spring force difference re a 919 length spring on a sc31 shock body.
That’s beyond whatever the installed preload force is intended to be for a 919 length spring on a 919 shock body.
Odd though, is the picture showing the free lengths being just 3 mm different, with the 919 free length also suggesting zero installed preload.
Something doesn’t seem quite right, as the 02 shock I have definitely has some installed preload.

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post #26 of 72 Old 07-10-2017, 05:17 PM
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Mcromo thanks for rep. Is possible than, that bought shock, seller listed as sc31, isnt in fact sc31.

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post #27 of 72 Old 07-10-2017, 06:36 PM
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Mcromo thanks for rep. Is possible than, that bought shock, seller listed as sc31, isnt in fact sc31.
I'll be honest by saying I do not know.
All along I've simply gone by the posts of others that F3 shocks are long and F4s are short.
I had never heard of sc31 nomenclature before.

Perhaps a better way to look at it is this way.
That is after making sure someone else has not already shortened the shock shaft and inadvertently taken away a bunch of stroke length!
With the bare shock at full extension and the preload collar at the softest setting such that the spring seats are at their greatest distance apart, confirm the spring seat to spring seat distance so you know for sure what the installed height will be.
Then it becomes a matter of looking for a spring of the right rate and length that can be fitted, perhaps necessitating adaptor seats re ID/OD fits and height re target installed preload.

Lastly, I just caught the fact that bushmaster in his original post had some good links for reference info.
Check out the Peter V' one, and if it has expired, try the Peter V' website.
I also suggest you try the Racetech website re installing GoldValves into OEM shocks, maybe there is some decent content there too.

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post #28 of 72 Old 07-10-2017, 06:41 PM
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The link to the Peter Verdone site still works, I just tried it.

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post #29 of 72 Old 07-10-2017, 11:51 PM
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as per sc31; thanks for notice. I realy did mistype it. It is actualy pc31. I will correct my upper post accordingly.

I live in EU market where Hondas and their parts, along with marketing names, come also with these additional codes as: PC and SC.
CBR600F3 - '95 to '98 additional code is PC31 (at least as per wikipedia)). My aim therefore was PC31.
Also when I need stuff for my Hornet 900, often there is also code CB900F - SC48.
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post #30 of 72 Old 07-11-2017, 12:08 AM
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Quote:
Originally Posted by go_slow View Post
OK, I went on sc31 shock project path. Was not satisfied with HYPER PRO springs.
-First I bought nitrogen filling eq.; honestly, dont yet know if it will be used at all
-Then I found sc31 shock on ebay.

acceptable I dont think I will fiddle with shock any more(as take apart).
I am a little woried about spring lenght. SC31 shock


In upper thread I did mistype code SC31, please disregard that. It should wright PC31 instead, the right code for F3.

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post #31 of 72 Old 07-14-2017, 11:07 AM
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1050#

1050# spring arrived.
I tried to fit 6’’ spring to F3’s 5’’ seat. Yeah, about that.... I have decided to keep all my fingers and go with mcromos (again many thanks! )solution plan: switch 919s reservoir with F3s. But this job is also postponed -whole nitrogen station is not yet complete/still waiting for some parts from china.

Of course I was curious what are free and riders sag’s with 1050#, did I buy correct? Next, 919 shock was dismantled, HYPERPRO spring was finally off and the new one fitted.

Results:
At 0 preload, position one, free sag was 20mm.
At position two: 15mm
Position 3:
- free sag 10mm;
- rider sag/geared 35mm;
W/O gear 77kg/170lb

…good enough for me. I went for a ride, and now I am sorry that I have waited so long with these modifications. Just replacing spring with correct rate spring, and ride is sooo much better.
First impressions: Rear end is firm on the ground and not hard at all, which I was afraid. Wobbling over 100mph almost disappeared. I think with front springs replacement it will probably disappear. Stumbling into larger holes rear lacks compression adj. , it dives too much.

a bit off topic?:
What I have learnt, that progressive is not good at all. Also here on forum one guy plainly explains progressive vs. linear, and why progressive is not ok; I would parse a link, but I couldnt find that thread any more.
I think its some kind of marketing propaganda success story, but physically installed and in use on the road, progressive is not working properly and is also illogical with regard to suspensions job.

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post #32 of 72 Old 07-15-2017, 07:10 PM
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Originally Posted by go_slow View Post
1050# spring arrived.
I tried to fit 6’’ spring to F3’s 5’’ seat. Yeah, about that.... I have decided to keep all my fingers and go with mcromos (again many thanks! )solution plan: switch 919s reservoir with F3s. But this job is also postponed -whole nitrogen station is not yet complete/still waiting for some parts from china.

Of course I was curious what are free and riders sag’s with 1050#, did I buy correct? Next, 919 shock was dismantled, HYPERPRO spring was finally off and the new one fitted.

Results:
At 0 preload, position one, free sag was 20mm.
At position two: 15mm
Position 3:
- free sag 10mm;
- rider sag/geared 35mm;
W/O gear 77kg/170lb

…good enough for me. I went for a ride, and now I am sorry that I have waited so long with these modifications. Just replacing spring with correct rate spring, and ride is sooo much better.
First impressions: Rear end is firm on the ground and not hard at all, which I was afraid. Wobbling over 100mph almost disappeared. I think with front springs replacement it will probably disappear. Stumbling into larger holes rear lacks compression adj. , it dives too much.

a bit off topic?:
What I have learnt, that progressive is not good at all. Also here on forum one guy plainly explains progressive vs. linear, and why progressive is not ok; I would parse a link, but I couldnt find that thread any more.
I think its some kind of marketing propaganda success story, but physically installed and in use on the road, progressive is not working properly and is also illogical with regard to suspensions job.
The 1050 numbers sound reasonable.
I suggest you make a point of testing position #4, you'll be a bit stiffer at full extension, but still have some free sag - say 5 mm or so, but the rear ride height will be up a bit when riding, which is a good thing.

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post #33 of 72 Old 07-18-2017, 09:19 AM
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Tried #2 and #4positions today. 2 felt plushier at 4 I could feel the rise, but front became more nervous. Front tend to float on the soft part of progressive spring, when is not loaded (straits, or when on full gas). On the other hand in hard corners front dives through soft prog. part of spring and becomes bit to hard. Only good behavior is on hard braking Prog. front has to be replaced with linear's. Am already looking for new fork springs. I think 8.5 would do.

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post #34 of 72 Old 07-18-2017, 09:22 AM
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Brake dive is controlled with damping not spring rate

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post #35 of 72 Old 07-28-2017, 05:56 AM
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PC31 shock, just laying there on the shelf, was making me restless. So I thought up how to fit 6’’ spring onto 5’’ seat and still retain 100% functionality. The entire shock, when you look at it, really has some place to lengthen the seat. I lengthen it by cutting preload adjuster (yellow line) and move preload adj. holder (two welded bits - circled with red ) 13mm toward shocks bottom. Bits were reinforced with welding little pieces of iron, just under those cut bits (green marking)
I then remove 1050# 6’’ spring from 919 shock, and fitted it to modified PC31 shock. Perfect fit, except reservoir hose is a bit long to hide… Sag figures same as with previous installation.
Adjusting preload now SUPER simple, comp. adj. located left under the seat
Not yet road tested
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post #36 of 72 Old 07-28-2017, 08:06 AM
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Back from the road. Shock is actually behaving not that well. 919 shock feels lot better.

On the road, with adjustments, I went from open comp. and reb., toward fully closed. Compression somewhat comply, but reb. is too much. Over bump it feels as if rear gets small kick(extend) when still on the bump. It should stay compressed just a bit longer and extend when over the bump.
Will try heavier oil. I don’t yet know what grade, 5 maybe 10W?. Brushbuster went with 10W, but with modified internals. Any idea, what grade is original F3 shock filled with?

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post #37 of 72 Old 07-28-2017, 10:59 AM
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post #38 of 72 Old 08-09-2017, 11:45 AM
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Shock successfully done

YEAH – did the shock! And its working fine

After installing linear fork springs from BITUBO, package bthw came with 20W oil , I continued my work on rear shock.
With safety goggles on, first thing - reservoir was drilled/zero nitrogen; nothing came out - empty!/, and disassembled. In order to fill nitrogen:hidden Schrader valve is installed to reservoir cap, by making hole with 12mm drill. Then I detached connection hose and drain oil from bladder and some from shock body. Body was disassembled, fully drained and cleaned then filled with 10W oil/and hope for the best .

When assembling, major difficulty was to bled out air. I did it trough hose to reservoir connection screw. When all parts was in place I took nitrogen tank, and with elevated hart rate/tank to shock connection gear is MacGyver style/ managed to fill shock reservoir with 200Psi of nitrogen.

Of course I had to install and test the shock right away. Immediately was felt that this is it; comp and rebound was set one turn out/in the middle of the range/, and that was pretty much settings I was satisfied with. Either one could be set slower or faster . I could not stop riding)

Recipe Sum: PC31 shock/preferably non leaking, spring/1000# or heavier, fresh 10W oil/cca 3dcl, new reservoir o-ring, nitrogen gear
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go_slow is offline  
post #39 of 72 Old 08-09-2017, 02:38 PM
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So how do you fill that and how do you know how much oil to add? I guess the oil just needs to be enough to cover full movement and nitrogen just needs to have enough volume to cover the movement of the oil without losing too much pressure.

So this just takes care of the reserve, does nothing for the other part of the shock in terms of opening, cleaning, seals etc?

BTW, what's the difference between this and the stock 919 shock? In other words, why couldn't you have done this with the stock shock?

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post #40 of 72 Old 08-09-2017, 03:13 PM
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Quote:
Originally Posted by KarlJay View Post

BTW, what's the difference between this and the stock 919 shock? In other words, why couldn't you have done this with the stock shock?
Because to the inexperienced "different" is always better. Doesn't matter to these guys that an OEM F3 shock was designed internally to be used with a progressive linkage where the 919 doesn't have one or that the OEM F3 shock was built to the same price point as the OEM 919 shock. Commonsense and logic goes right out the window in some sort of "I'm a cheap ass motorcycle fixer upper, watch me save all this money" martyrdom fantasy.

I have never understood the idea of reworking OEM shocks and refuse to do it for my customers as the return on the investment is just too low. I would not feel good about myself charging money to give someone back that little tiny bit of improvement. What's worse is most of these guys don't even know if the changes they are making are an improvement or not. They could just as easily be making it worse, but you rarely hear the truth on forums like these.

Further down my list of shit I would never do is swap one OEM part for another OEM part. There is a reason quality aftermarket parts exist. That reason is to replace shitty OEM parts period.

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