Increasing tire pressure transforms 919 handling! - Wrist Twisters
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post #1 of 37 Old 02-21-2016, 03:05 PM Thread Starter
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Increasing tire pressure transforms 919 handling!

Okay, this is not news to some. I have never been happy with the way my 919 feels in corners, just a little sluggish and vague. I had considering trying to raise my tire pressure, but it seems the threads here are 50/50 on whether lower pressures or higher pressures are better. I've always kept my tires at 30-35 psi on my previous bikes, and did the same with my 919.

Finally, on the advice of a guy who test rode the bike, I increased the rear to 39 psi, front to 36 psi (on Michelin 2CTs) and just did a twisty ride today. Night and day difference. No longer sluggish. Felt great, very nimble and responsive. This, along with my seat modification (which is still a duct tape and foam prototype) has definitely tipped the scales in my judgement of the 919 as a bike I can live with.
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post #2 of 37 Old 02-21-2016, 03:25 PM
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Quote:
Originally Posted by Manzanita View Post
Okay, this is not news to some. I have never been happy with the way my 919 feels in corners, just a little sluggish and vague. I had considering trying to raise my tire pressure, but it seems the threads here are 50/50 on whether lower pressures or higher pressures are better. I've always kept my tires at 30-35 psi on my previous bikes, and did the same with my 919.

Finally, on the advice of a guy who test rode the bike, I increased the rear to 39 psi, front to 36 psi (on Michelin 2CTs) and just did a twisty ride today. Night and day difference. No longer sluggish. Felt great, very nimble and responsive. This, along with my seat modification (which is still a duct tape and foam prototype) has definitely tipped the scales in my judgement of the 919 as a bike I can live with.
Good deal. I have always just run mine on the high side too. Post up some pics of the duct tape seat mod!

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post #3 of 37 Old 02-21-2016, 07:17 PM
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I run 36/42. I could really tell a difference when the pressure started to drop. I am by no means an expert, but, the sticker says 36/42 and I have seen good results. Why change...

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post #4 of 37 Old 02-21-2016, 07:34 PM
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Quote:
Originally Posted by Manzanita View Post
Okay, this is not news to some. I have never been happy with the way my 919 feels in corners, just a little sluggish and vague. I had considering trying to raise my tire pressure, but it seems the threads here are 50/50 on whether lower pressures or higher pressures are better. I've always kept my tires at 30-35 psi on my previous bikes, and did the same with my 919.

Finally, on the advice of a guy who test rode the bike, I increased the rear to 39 psi, front to 36 psi (on Michelin 2CTs) and just did a twisty ride today. Night and day difference. No longer sluggish. Felt great, very nimble and responsive. This, along with my seat modification (which is still a duct tape and foam prototype) has definitely tipped the scales in my judgement of the 919 as a bike I can live with.
Im not going to recommend a specific pressure but I think you are compensating for crappy front suspension with it, and I dont think that would give me alot of confidence.

What does transform the bike is replacing the springs in front and setting up the suspension correctly. This I have done and its not the same motorcycle. Careful playing with tire pressure.

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post #5 of 37 Old 02-22-2016, 06:13 AM
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Originally Posted by theboom View Post
Im not going to recommend a specific pressure but I think you are compensating for crappy front suspension with it, and I dont think that would give me alot of confidence.

What does transform the bike is replacing the springs in front and setting up the suspension correctly. This I have done and its not the same motorcycle. Careful playing with tire pressure.
I didn't know the front springs were a weak point. Is the standard replacement the progressive set or is there some other setup?

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post #6 of 37 Old 02-22-2016, 08:03 AM
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Originally Posted by KarlJay View Post
I didn't know the front springs were a weak point. Is the standard replacement the progressive set or is there some other setup?
The more common replacement, and certainly the most dominant one for riders on this website, is single rate springs, typically Ohlins or Racetech or Traxxion.
A huge improvement in the front end can easily and inexpensively be realized by springs, oil and oil level.
Don't forget proper adjustment the rebound adjuster on the 04 and later models, that too helps.
Last point, back to springs, when re-springing, keep in mind that replacement springs are intended for fitting with a relative installed preload that has zero to do with the lengths of the stock spring's free length and it's related spacer length.

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post #7 of 37 Old 02-22-2016, 08:24 AM
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Quote:
Originally Posted by Manzanita View Post
Okay, this is not news to some. I have never been happy with the way my 919 feels in corners, just a little sluggish and vague. I had considering trying to raise my tire pressure, but it seems the threads here are 50/50 on whether lower pressures or higher pressures are better. I've always kept my tires at 30-35 psi on my previous bikes, and did the same with my 919.

Finally, on the advice of a guy who test rode the bike, I increased the rear to 39 psi, front to 36 psi (on Michelin 2CTs) and just did a twisty ride today. Night and day difference. No longer sluggish. Felt great, very nimble and responsive. This, along with my seat modification (which is still a duct tape and foam prototype) has definitely tipped the scales in my judgement of the 919 as a bike I can live with.
Keep in mind that in terms of tire design and pressure tuning, maximum grip is associated with carcass deflection that results in some level of stability loss.
I interpret your comments above as being stability based and not at all grip based.
You might find that a tire more oriented towards touring to feel better to you, as in with a more stable carcass design.
Also, how good is your gauge? Does it by change over read a bit in the zone you are using it in?
I've run 2CTs and found them to be extremely stable in the 32F and 35 R zone, both cold settings.
You may also have some other things going on.
Are your steering head bearings OK?
If you have an 04 or later, do you have enough rebound dialled in?

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post #8 of 37 Old 02-22-2016, 12:10 PM
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How much do you weigh Manzanita? Are you carrying a passenger?

Maximum pressure of the tires at 36/42 is for carrying the maximum weight rating of the bikes capacity which is usually around 360-400lbs. If you are heavy enough to come close to that maximum rating then you will likely find favorable characteristics out the tire from using that much pressure. If you weigh less than that then reasonably lower tire pressures will offer more grip, comfort and compliance from the tire than the maximum pressure will.

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post #9 of 37 Old 02-22-2016, 12:26 PM
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Quote:
Originally Posted by LDH View Post
How much do you weigh Manzanita? Are you carrying a passenger?

Maximum pressure of the tires at 36/42 is for carrying the maximum weight rating of the bikes capacity which is usually around 360-400lbs. If you are heavy enough to come close to that maximum rating then you will likely find favorable characteristics out the tire from using that much pressure. If you weigh less than that then reasonably lower tire pressures will offer more grip, comfort and compliance from the tire than the maximum pressure will.
So, with that said, is there a matrix somewhere out there that shows what the tire pressures should be? I weigh about 225. I usually carry a backpack or tail bag.

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post #10 of 37 Old 02-22-2016, 12:35 PM
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Quote:
Originally Posted by bartsitarski View Post
So, with that said, is there a matrix somewhere out there that shows what the tire pressures should be? I weigh about 225. I usually carry a backpack or tail bag.
No there is some trial and error and personal preference involved as every tire model is different in terms of carcass designs and belting plies etc.

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post #11 of 37 Old 02-23-2016, 06:41 AM Thread Starter
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Hmm, well this is interesting input, thanks all.

I weigh 180 lbs. It is 2003 919.

I have gone through a few suspension upgrades, first with rebuilt front forks (0.9 kg/mm linear springs with 5W oil, setup by Catalyst Reaction), then adding a Ohlins rear (no external reservoir), 1000 lb. spring. They have checked it out a couple times, checking for stiction and are saying it is working well. They have also checked the front headset and say it is okay. Overall the suspension is not perfect, but it is 1000% better--as far as being a compromise of small bump absorption and stability in turns.

I think one variable may be the roads I like around here, where there are many tight low speed turns, really fun, but I am taking them at 25-35 mph and having to throw the bike side-to-side a lot. Here was part of my route on sunday: https://goo.gl/maps/N8bKGR3PDF12. I think there may be riders that go out of there way to avoid roads like this, and call them 'goat trails' but it's what I enjoy.

I am definitely not pushing the limits of grip and the biggest safety factor is sand and dirt on the road in blind corners.

I have had mostly lighter bikes (a ninja 250 for a couple years), although my Honda cx500 was the bike I spent the most miles on, and it weighed almost as much as the 919--but it was also on a 130mm rear tire, and felt very nimble on these roads.

I was think of switching to more of a sport touring compound, think of the Angel ST, but there are some nice sportier tires out there for cheap, I love continentals and there is a rear sport attack for $120, and the Bridgestone S20 Evo is also very inexpensive and gets great reviews.

The 2CT looks like it has a very pointy profile and would turn-in quickly, but at lower pressures (30/33) the bike doesn't feel that way to me--but I think it is all relative to what I've ridden. Feeling the tire, it certainly feels like a super sticky compound for sure.

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post #12 of 37 Old 02-23-2016, 07:08 AM Thread Starter
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@marylandmike: seat mod is too ugly for pics, maybe version 2.0 will be an improvement, I have more black duct tape on order... I have added about 3 inches of height to the front, almost completely filling in the cutout. Although the foam does compress (I am using exercise mat foam), I am now on my toes when I straddle the bike so it is definitely higher. Yeah, the whole thing needs to be torn off and redone, I didn't realize how much of my butt goes further back on the seat towards the ridge, it needs to be wider back there... but the basic idea of raising and leveling out the front downsloping section of the seat is working for me for sure.

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post #13 of 37 Old 02-23-2016, 08:53 AM
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Quote:
Originally Posted by Manzanita View Post
I have had mostly lighter bikes (a ninja 250 for a couple years), although my Honda cx500 was the bike I spent the most miles on, and it weighed almost as much as the 919--but it was also on a 130mm rear tire, and felt very nimble on these roads.
You really cannot compare bias ply tires on a 35 year old bike to radials on a modern chassis. Those are two completely different types of feedback among many other very important differences in the design scope of the chassis.

That being said I have a CX500 with a 130 tire in my office right this second and I love it very much

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post #14 of 37 Old 02-24-2016, 12:19 AM
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That being said I have a CX500 with a 130 tire in my office right this second and I love it very much
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post #15 of 37 Old 02-24-2016, 05:20 AM
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Wow! nice CX500 LDH. I remember seeing those on the show room floor back in the day. Brings back good memories! thanks for sharing!

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post #16 of 37 Old 02-25-2016, 02:06 AM
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You don't have a Suzuki rotary, too, do you - the one with the coffee flask dash? Or an XJ650T?

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post #17 of 37 Old 02-25-2016, 09:53 AM
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You don't have a Suzuki rotary, too, do you - the one with the coffee flask dash? Or an XJ650T?
I have never owned an RE-5, but I did have a Seca Turbo many many years ago. 83 whopping rwhp out of that turd with blow thru carbs and the finish was crap as well.

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post #18 of 37 Old 02-28-2016, 04:57 AM
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I don't think I'm going to jump on the 39 psi (cold) idea just yet. Go for a hard ride on a hot day, and check the temp. It'd be interesting to see what it climbs to. The pressure may go another 6 psi. I'm not comfortable with that. I want a bigger contact patch, and a bit more compliance. The 599, and Super Duke are both just over 400 pounds (while low on fuel), and Im 180 ish. The 399's owners manual says 29, and that's exactly where I run it.

After the demise of the 81-82 900F, it took me a long time to warm back up to what Honda had to offer in the mid 80s. Never cared for the CX, Magna's sucked, Sabers were ok, the first Interceptors were kind of cool, but eventually didn't live up the the hype. Honda didn't do anything really cool until the 900RR. The worst enemy of most motorcycles, are the slugs that buy them, and mod/abuse/neglect them into the trash heap that is most 30 year old motorcycles. Nice to see one that was treated correctly.

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post #19 of 37 Old 03-10-2016, 08:00 PM Thread Starter
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Originally Posted by mcromo44 View Post
Keep in mind that in terms of tire design and pressure tuning, maximum grip is associated with carcass deflection that results in some level of stability loss.
I interpret your comments above as being stability based and not at all grip based.
delayed response on reading this again... it seems at lower PSI the bike is sluggish, (too stable?) and less easy to initiate turns. At higher PSI the bike tips in easier and just feels lighter. Yeah, smaller contact patch, less total grip... but feels better. I did try to experiment and lowered the pressure to 33 front, 36 rear, and although it was subtle, I would say it felt a tad heavier.

My other bike, a 2014 Zero S has such a quick, twitchy geometry that I immediately swapped out the tires to Pilot Road 3s, and it definitely helped stabilize the bike and gave it a more gradual turn-in. So switching back and forth between the Zero and 919 may be part of my perception that the 919 is slow and that higher PSI feels better.

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post #20 of 37 Old 03-10-2016, 08:59 PM
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Originally Posted by Manzanita View Post
delayed response on reading this again... it seems at lower PSI the bike is sluggish, (too stable?) and less easy to initiate turns. At higher PSI the bike tips in easier and just feels lighter. Yeah, smaller contact patch, less total grip... but feels better. I did try to experiment and lowered the pressure to 33 front, 36 rear, and although it was subtle, I would say it felt a tad heavier.

My other bike, a 2014 Zero S has such a quick, twitchy geometry that I immediately swapped out the tires to Pilot Road 3s, and it definitely helped stabilize the bike and gave it a more gradual turn-in. So switching back and forth between the Zero and 919 may be part of my perception that the 919 is slow and that higher PSI feels better.
You're on to something.
A pure road tire will slow down a front end.
A pumped up tire will speed up a front end, but introduce harshness and reduce grip to some degree.
The 919 is a nominal 26 degree steering head angle with 98 mm of Trail.
Some supersports are down into the 23 degree zone with similar Trial and are lightning quick in comparison.
My 919 has the chassis set up as track day oriented but still streetable on the firm side.
My GSX-R 750 has a complete front end build and a Penske 3 way out back.
Switching back and forth the difference screams out, the 919 is like riding on a big comfy two wheeled couch, while the 750 is like a two wheeled race kart in comparison.
(There's also around 100 # of difference between the two.)
As LDH has said more than once, you can't make a 919 into a supersport.
BUT a nicely prepped one can really be hustled around a track, and is a very forgiving platform, just as they are on the street.

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post #21 of 37 Old 03-18-2016, 09:39 PM
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Tire pressure seriously affects every bike for the most part. Not trying to be a b.hole by saying that, but it just seems like every bike specific forum or thread I see someone always has that same observation and it stands to reason... The tire dynamics on a bike are really not the same as cars. They are much more sensitive to tire pressure.

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post #22 of 37 Old 03-19-2016, 01:49 AM
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Quote:
twitchy geometry that I immediately swapped out the tires to Pilot Road 3s, and it definitely helped stabilize the bike and gave it a more gradual turn-in.
My primary objection to dicking with tire pressure to improve the 919's awful handling is just that. If you are using PSI to make the bike handle you are doing it wrong and could end up in the ditch.
The tire does not control "twitchy" geometry or "gradual turn-in" although you could force that with extreme low or high pressure.

A 919 with proper suspension (ohlins and a proper setup) exhibits neither twitchy geometry or "gradual turn-in". The shock is bad enough but most of this thread is really talking about the substandard forks on the 919.

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post #23 of 37 Old 03-19-2016, 01:53 PM
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My primary objection to dicking with tire pressure to improve the 919's awful handling is just that. If you are using PSI to make the bike handle you are doing it wrong and could end up in the ditch.
The tire does not control "twitchy" geometry or "gradual turn-in" although you could force that with extreme low or high pressure.

A 919 with proper suspension (ohlins and a proper setup) exhibits neither twitchy geometry or "gradual turn-in". The shock is bad enough but most of this thread is really talking about the substandard forks on the 919.
919s handling is not awful. It works as designed as budget mass produced bike. No amount of Ohlins and fork work will fix that.

Yes the tyre profile has an affect on "tip in". A road tyre like a PR3 will be very neutral where a Conti race will fall in. You choose the tyre profile to get the feel you like. Adding high pressure to a road tyre to deform it to change profile is a great way to go for a slide.

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post #24 of 37 Old 03-20-2016, 06:25 AM
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Quote:
Originally Posted by NZspokes View Post
919s handling is not awful. It works as designed as budget mass produced bike. No amount of Ohlins and fork work will fix that.
I have to disagree with this statement. I re valved and sprung the forks and added the shock, all Ohlins, and it completely changed the handling for the (MUCH) better.
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post #25 of 37 Old 03-20-2016, 10:46 AM
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I have to disagree with this statement. I re valved and sprung the forks and added the shock, all Ohlins, and it completely changed the handling for the (MUCH) better.
You and me both.
A 919 can easily be transformed into a very track day worthy street bike, and that says it all.
Sure, put a pro rider on it and a set of super sticky DOT race tires or race slicks, and a pro will be able to tie it in a knot - but keep the rubber down and the helmet up while doing so.
The 919 is an UJM in the tradition of the SOHC CB750 and the Z1 and the GS1000s of old.
Like any good UJM, the 919 does all well, but won't be the best at anything - aside from being the best truly fully naked UJM like bike of recent years with a single round headlight.
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post #26 of 37 Old 03-20-2016, 10:53 AM
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Quote:
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Yes the tyre profile has an affect on "tip in". A road tyre like a PR3 will be very neutral where a Conti race will fall in. You choose the tyre profile to get the feel you like. Adding high pressure to a road tyre to deform it to change profile is a great way to go for a slide.
For sure !

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post #27 of 37 Old 03-21-2016, 03:56 AM
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I have to disagree with this statement. I re valved and sprung the forks and added the shock, all Ohlins, and it completely changed the handling for the (MUCH) better.
Agree they can be improved on. But they will never be a stunning handling bike. Enjoy them for what they are.

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post #28 of 37 Old 03-21-2016, 07:28 PM Thread Starter
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My primary objection to dicking with tire pressure to improve the 919's awful handling is just that. If you are using PSI to make the bike handle you are doing it wrong and could end up in the ditch.
The tire does not control "twitchy" geometry or "gradual turn-in" although you could force that with extreme low or high pressure.

A 919 with proper suspension (ohlins and a proper setup) exhibits neither twitchy geometry or "gradual turn-in". The shock is bad enough but most of this thread is really talking about the substandard forks on the 919.
First off, when I mentioned twitchy geometry and more gradual turn-in with different tires, I was writing about my Zero S, not the 919, and those comments were not related to tire pressure.

My original post I say I set it at 3 PSI below the OEM recommended 42 PSI rear, so I don't think that is an extreme high pressure.

And just to repeat, this is not on a stock 919, I have a rear Ohlins and had the front forks professionally tuned and rebuilt with linear springs. So I don't think this thread is talking about the substandard front fork. I think I do have more confidence in corners with the new suspension in that the bike responds better to irregular surfaces, but I still think it has a lighter feel with higher tire pressures... which I know is a compromise as far as max grip... but I don't think I'm pushing the bike that hard on the street...

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post #29 of 37 Old 03-22-2016, 04:32 AM
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The responses to this thread are in two categories, does messing with tire PSI improve 919 handling. Answer: NO.
Does actually improving the 919 handling with suspension upgrades. YES.

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post #30 of 37 Old 03-22-2016, 04:40 AM
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And frankly, Im sick of this argument, theres plenty of ways to improve the handling of the 919,

Shake your ass and shimmy around a turn,
Grip the bars like maniac,
Tighten your asshole,
Push in the opposite direction,
Lose Weight,
Pray to Buddha you dont end up in a ditch,
Get track lessons and learn how to die correctly.

And all of those fucking things, dont add up to a controllable, much less fun motorcycle within the range of safe suspension parameters for a given rider.

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post #31 of 37 Old 03-27-2016, 05:11 PM
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My two cents: I weigh 130-135 with all my gear on and I had the suspension on my '04 919 set pretty stiff for the road. I'm probably one of the lucky few that doesn't find the stock suspension inadequate lol. I had Pilot Road 3s and kept them at 36/42 and definitely noticed if they dropped a few pounds-- kind of a wallowy feeling and the shitty grooved pavement that is so prevalent on my commute would make the bike wander more than usual. I was advised to set them at 30/30 for a track day and I thought it would feel crazy low but the tires heated up so quickly I didn't even notice. The next track day I forgot to lower the pressures for the first session and I had to get off the track after three laps because it was bouncing me all over the fucking place.

Almost all modern standards and sportbikes call for 36/42 for regular road riding on the manufacturer's frame stickers. I figure I don't have any reason to think I know better than they do.

Fine, I'm adding a signature, leave me alone!
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post #32 of 37 Old 03-29-2016, 01:33 PM
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Originally Posted by derpydog View Post

Almost all modern standards and sportbikes call for 36/42 for regular road riding on the manufacturer's frame stickers. I figure I don't have any reason to think I know better than they do.
Ahhhh, you must be Lawyer ! LoL

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post #33 of 37 Old 03-29-2016, 03:15 PM
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Quote:
Originally Posted by mcromo44 View Post

Ahhhh, you must be Lawyer ! LoL
They made the probability 99.9% popular.

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post #34 of 37 Old 03-30-2016, 10:00 AM
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When I first bought my '02 used the tires were old and weather checked, so I had them replaced them with Pilot Roads before taking delivery. At first they were very uncompliant over irregular pavement, and felt horrible when leaning into a corner. When checking pressures I found them at placard levels, and dropped them to 28 front and 31 rear. WHAT A DIFFERENCE!!! Compliance was considerably better, braking more sure and predictable, and it went from not wanting to initiate a lean predictably to needing the smallest input from the bars combined with body English to dive into corners hard enough to tag the pegs (no feelers) with no drama.

Frankly, I would not ride with full placard pressures unless I was transporting the family anvil collection.

Of course I know what I am doing, and that really makes a big difference.

Rob
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post #35 of 37 Old 06-30-2016, 11:51 PM Thread Starter
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Lowering Tire Pressure Transforms 919 Handling!

I may be sounding like a troll, and I know I will get slammed on this forum, but just wanted to give an update, FWIW.

I replaced the Michelin 2CTs with Continental Sport Attacks, and found that lowering my pressure to 32/32 did not make the bike feel sluggish like with the 2CTs.

Then I read a thread on BARF about lowering tire pressure to compensate for suspension, and my front suspension still does not absorb small bumps and irregularities the way I want it to... so I went and lowered my front to 28 psi, and it is definitely more compliant and absorbing rough road better, I definitely like it, with maybe a little more instability coming out of corners. Importantly, these tires have none of the sluggish feel at lower pressure. The weird thing is that by visual inspection these different tires have a very similar profile--maybe the conti is slightly more triangular, and they definitely feel lighter weaving from a straight line.

So I am sticking with 28 front/ 32 rear for these tires, despite liking 35/38 or so with the 2CTs...

With this success I went crazy and lowered my PR4 front on my Zero to 28 psi... failed experiment. That tire has the sides completely worn off, and was starting to feel unstable in corners anyways, and lowering to 28psi has made it worse. I have a new tire set waiting for that bike (Conti Road Attack II Evo rear, Metzler M7 RR front). More tires to test, Yay!

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post #36 of 37 Old 07-01-2016, 02:34 AM
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has anyone ever ridden on slicks before? im just curious to know how they feel compared to top tier road tires.

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post #37 of 37 Old 07-01-2016, 08:31 AM
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Quote:
Originally Posted by nathanktm View Post
has anyone ever ridden on slicks before? im just curious to know how they feel compared to top tier road tires.

Almost every time I ride

Slicks are just like DOT Tires in terms of how many different types of construction there are for the belting and carcass etc. The feel of slicks varies just as much as the feel and feedback of street tires. Many of them currently have stiffer sidewalls to compensate for the belting design that leaves a huge contact patch on the ground when leaned over and requires as little as 19Psi cold which is pretty amazing when you look at what they are capable of. Then again current DOT street tires from the big name brands are no slouches in the grip department when used at the track either and the DOT Race Tires in many cases are identical to their Slick style siblings except with a tread pattern.

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