919 Spring Rates - Wrist Twisters
 
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post #1 of 19 Old 03-28-2009, 06:39 PM Thread Starter
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919 Spring Rates

Does anyone know the stock spring rates for the 919 suspension?

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post #2 of 19 Old 03-29-2009, 07:07 PM
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Really soft.

Racetech's web site doesn't say. I've had mine out, no markings to say what they are either. You can call racetech or Traxxion. They can tell you, they just don't list it on their site.

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post #3 of 19 Old 03-29-2009, 07:17 PM
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if you call them and find out let us all know please. could be some good info for use to have in the back of our minds

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post #4 of 19 Old 03-29-2009, 10:16 PM
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forks are .75kg and they are progressive springs.

'04 919---40k----6/18/10 SOLD

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post #5 of 19 Old 03-30-2009, 01:19 AM
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so... i could move to like a .9 since i weigh about 190 with all my duds... and it might be ballpark stiff enough!

30,000 mile 919 survivor. No plans of stopping the abuse any time soon.
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post #6 of 19 Old 03-30-2009, 08:24 AM
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so... i could move to like a .9 since i weigh about 190 with all my duds... and it might be ballpark stiff enough!
.9 would be perfect for you. the 1kg springs are for 210lbs riders I believe.

Racetech has a calculator for you to use.

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post #7 of 19 Old 03-30-2009, 08:40 AM
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The springs in the forks are a bit on the soft side. The rear shock spring is way too hard. If you ride with a passenger, it works pretty well, because that's what the bike is set up for. If you ride solo, it needs some work.

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post #8 of 19 Old 03-30-2009, 09:55 AM Thread Starter
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On another thread it was mentioned that a CBR600F3 shock would fit on a 919. I have compared the 2 and they match in the regard that that the entire shock absorber is the same length (the F3 shock is actually 3 or 4 mm longer), and the mounts match. The hose to the reservoir is longer on the F3 shock, but that is a small issue.

I am wondering if the spring rates and valving on the F3 shock would actually 'improve' the 919's suspension. See this chart:

http://www.penskeshocks.com/motorcyc...ATIONCHART.pdf

If you compare the shocks side by side the spring is the same length, but this is sort of misleading. According to the chart the F3 spring is 6 inches, the 919 spring is 5 inches...Does that mean the F3 spring is compressed more? Also, the the 919 spring is a bit stiffer.

Any suspension gurus or ex-racers want to take a stab at this?

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post #9 of 19 Old 03-31-2009, 02:12 AM
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the only thing i am a guru for is smuggling from my beer fund for my parts fund... but isn't the F3 a linkage style suspension?

30,000 mile 919 survivor. No plans of stopping the abuse any time soon.
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post #10 of 19 Old 03-31-2009, 04:54 AM
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Just have to search for F3 spring rates. If its compressed more it may be softer rate. But it could just as easily be harder. It all depends on the motion ratio of the F3.
Is the F3 shock servicable? If so then who cares what spring is in it. It can be changed. As well as the fluid and maybe the valves.

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post #11 of 19 Old 03-31-2009, 06:38 AM
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The springs in the forks are a bit on the soft side. The rear shock spring is way too hard. If you ride with a passenger, it works pretty well, because that's what the bike is set up for. If you ride solo, it needs some work.
I totally agree with you! My front shocks seem way to soft, especially when I stop. It dives way to much! But the rear shock is way too hard. In fact, when I took my bike in to the dealer to get my first 600 mile service, I had them stiffen the front and soften the rear.

As for "spring rate", I may sound brain dead (it's the Coronas every night) but I don't really know what that technical term means.

But I can tell you THIS for certain...

In the Honda Service Manual for the 919, it says this:
Front axle travel: 109mm (4.3 inches)
Spring free length: 282.3mm (11.1 inches)

Not sure what exactly help if any those numbers are, but all I know is I'm going to follow this thread to the end because I keep wondering about getting a stiffer front spring set.

post #12 of 19 Old 03-31-2009, 06:59 AM Thread Starter
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Spring rate is the stiffnesss of the spring.

Preload sets the 'initial' stiffness of the spring. It also will slightly change the ride height with a rider on board, with in turn will change the rake and trail, which directly affects steering quickness and stability.

Increasing preload means compressing the spring, decreasing preload means de-compressing the spring. If you have an 04+, you have adjustable preload on your forks (I have an 02). If the forks do not have adjustable preload, you can still set it by using a different length spacer at the top of the fork -- longer for more preload, shorter for less. PVC pipe works well. This is a fairly common mod for Suzuki Bandit owners.

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post #13 of 19 Old 03-31-2009, 07:32 AM
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So is there any way of stiffening my front springs without buying new ones? One guy told me in town that just thicker spring oil would help. Is that true? I don't really think I'm really ready to rip my forks apart and install new springs. But I'm guessing it couldn't be too hard if I keep my trusty Honda Factory Service Manual and a few cold ones neaby.

Of all the google searches and online retailer searches I've done for "919 front fork springs", Progressive seems to be the brand that pops up most. Any reason for that? Are they better or worse than other brands?

post #14 of 19 Old 03-31-2009, 07:54 AM Thread Starter
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Quote:
Originally Posted by hairball919 View Post
So is there any way of stiffening my front springs without buying new ones? One guy told me in town that just thicker spring oil would help. Is that true? I don't really think I'm really ready to rip my forks apart and install new springs. But I'm guessing it couldn't be too hard if I keep my trusty Honda Factory Service Manual and a few cold ones neaby.

Of all the google searches and online retailer searches I've done for "919 front fork springs", Progressive seems to be the brand that pops up most. Any reason for that? Are they better or worse than other brands?
Changing the fork oil to a higher weight won't make the springs any stiffer. It will slow the compression and rebound response. This would make the ride seem firmer, and would likely result in poor handling. Personally, I would not do this.

I am guessing you do not have adjustable preload...you could add PVC spacers inside the fork tubes or buy new springs.

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post #15 of 19 Old 03-31-2009, 09:02 AM
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hmmm....pvc spacers, eh? how long?

Well, fire the engines! Spur this iron space-pony on!

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post #16 of 19 Old 03-31-2009, 09:05 AM
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...I am guessing you do not have adjustable preload...
I think I do (I have whatever an 07 919 has), but I didn't think it would make it that much firmer and eliminate the huge amount of dive when I brake. Another forum member told me on a ride once that if I stiffen the front too much it will handle like crap in the twisties and that I want some dive. But do I really? Certainly not when I brake!

(See, I'm still checking this thread every chance I get)

post #17 of 19 Old 03-31-2009, 09:47 AM Thread Starter
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hmmm....pvc spacers, eh? how long?
http://books.google.com/books?id=S5t...esult#PPA92,M1

Look at pages 92 & 93, here is a description of using PVC to adjust preload. The stock 919 forks already have a spacer, called a spring collar in the service manual. Without taking the forks apart, I don't know the length of the spring collar. As far as the length of the PVC, I've never done it on a 919 so it would be trial and error. I would make several lengths starting with 1/4 inch longer than stock and increase in 1/4 inch increments.

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Originally Posted by hairball919 View Post
I think I do (I have whatever an 07 919 has), but I didn't think it would make it that much firmer and eliminate the huge amount of dive when I brake. Another forum member told me on a ride once that if I stiffen the front too much it will handle like crap in the twisties and that I want some dive. But do I really? Certainly not when I brake!

(See, I'm still checking this thread every chance I get)
Think of preload as ride height with the rider on board:

--Increasing preload, increases ride height (decreasing reduces it)
--Increasing FRONT preload will increase rake and trail...this will reduce steering sensitivity and increase stability. The opposite is also true.
--Increasing REAR preload will decrease rake and trail...this will increase steering sensitivity (too much is bad) and decrease stability. The opposite is also true.

Finding the balance is the trick. The settings in the manual are a good starting point.

You are going to have SOME brake dive no matter what...unless you get a BMW with Telelever/Paralever suspension.

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post #18 of 19 Old 03-31-2009, 10:26 AM
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Sniper, what year is your 919?

it seems like some ppl say their 919's forks are too soft and the shock is too stiff. my 2002 919 feels like just the opposite, and i'm about 170 lbs.

I'm wondering if the fork vs shock stiffness/softness is related to pre and post '04 919's?



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post #19 of 19 Old 03-31-2009, 10:32 AM Thread Starter
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Sniper, what year is your 919?

it seems like some ppl say their 919's forks are too soft and the shock is too stiff. my 2002 919 feels like just the opposite, and i'm about 170 lbs.

I'm wondering if the fork vs shock stiffness/softness is related to pre and post '04 919's?
'02-'03 use different front springs from the '04+, not sure what the exact rates are. The front on my '02 does not seem overly soft.

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