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Discussion Starter · #1 ·
At 140ish I get a headshake so bad I have to get out of the gas. I tried everything. I am at a loss on how to fix and looking for suggestions.
 

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Bike

What Bike?

Steering head bearings?

Cupped tires?

Swingarm Bearings?

Wobble or headshake?

Headshake is normally on hard acceleration and the front tires gets light.

Steering Dampener?
 

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Discussion Starter · #3 ·
What Bike? 2008 1098

Steering head bearings? OEM, I will try a little tighter torque now that you mention it. Thanks.

Cupped tires? New Michelin Slicks

Swingarm Bearings? Checked, but I will check again.

Wobble or headshake? Based on your note, let's go with wobble.

Steering Dampener? Ohlins

Bike works great in turns, has excellent tire wear, no problems on the brakes.

Rear height was varied between 215 and 235mm using Ducati tool
Has Kyle rocker
Front was varied from flush to -3 lines.

I went from full front raised/rear low to the opposite. It appears that there is a spot in the middle that works, but it sort of freaks me out that there is such a small range of goodness.

Front sag 40mm, rear 30mm

I have also fooled around with comp/reb settings, but mostly this seems to be helping turns/bumps/tire wear and has not dome anything to improve this issue.

I tried a stiffer rear spring and it made everything more sensitive to the ride height settings.

With the front high/rear low setting, and stiff spring, I could ride around it by sliding my butt forward, gripping the tank hard with my legs, letting go of the bars, with very high setting (10 clicks) on the damper.
 

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Hello Bob,

I have found that the Michelin slicks are very picky when it comes to suspension setup. They deliver a lot of confidence when leaned over, almost to the extent when you would think your ears will touch the ground.

But as I said I found the front tyre very difficult to setup. A swap to Continental Race slicks the very day took away all of the problems.

What type of Michelin are you using? My experience was with a S1246. I have a new Power One Slick sitting here waiting for its judgement day at the end of July. So I can´t comment on those yet.

It is good to see that someone is actually thinking about suspension and geometry. It might be advisable to talk to your suspension tech if he can work out a Michelin setup. If he´s good he should know the differences between tyre brands and usable setups. If you can´t get to grips with the whole thing, I can try and call my tyre buddy. He is good with the guys from the Michelin Power Research endurance team, so maybe he would know. I´d try to talk to your suspension guy first.
 

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Discussion Starter · #5 ·
I have been using the 1246 pretty much exclusively. I agree about leaned over performance, they rock, and the contingency is the best in the business. I will see if they have a Power 1, sounds like something worth trying. Thanks for the tip!
 

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Bearings

Pull your triple and inspect the bearings. Might have crunched or lost them.

Crashed recently and possibly tweaked the triple or a fork tube? Might be subtle if you did not do it bad and would show up at high speed.
 

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I have been using the 1246 pretty much exclusively. I agree about leaned over performance, they rock, and the contingency is the best in the business. I will see if they have a Power 1, sounds like something worth trying. Thanks for the tip!
Bob can you let us know what your static sag numbers are front and rear?

If you get to try the Power One, let us know how you fare.
 

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Discussion Starter · #8 ·
40mm front, 30mm rear.

Next event is on the 16th/17th, it's the Streets of Willow, so I don't hit those top speeds. Big track is Aug 21st, so won't really know till then.

I am asking Dale Keifer at Racers Edge what other fronts we can try. I used the DOT rear and the slick rear with no change but I like the slick better.
 

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My .02.

First off, going from the Pirelli's to the Michi's, did you measure axle height of both the front and the rear? Different profiles and characteristics warrant different chassis adjustments based on tire diameter. Second, did you change rear profile or keep it the same(just checking)?

Measure the front fork length from triple top to center axle, and front axle height. xx98 model bikes are ~694mm. You can flush the forks if you want, however I would refrain from playing with it until you get chassis attitude correct.

Remeasure rear ride height, rear axle pivot AND swingarm pivot height. Stock height is ~225mm/376mm. Raise the rear ride height to 240mm, and play 2mm at a time towards the taller side of height until you start getting a better feel.

Since you have a linear rocker, I would recommend setting rear squat at 20mm, then make 1-2mm adjustments from there. 40F/30R is a bit soft for someone wanting to hit warp speeds.

Once you get a good feeling, then experiment with CofG height.

I would say lastly, how is your body position when at said warpness? Butt back as far as possible or are you close to the tank? Are you laid out flat(less drag) or taller up so try and see(more drag).
 

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Discussion Starter · #15 ·
Hey thanks for the posts and the numbers to check. We raced on the Streets of Willow this month, so was not able to evaluate the issue since the course is much slower. But, I will get back to you on how my bike compares with your numbers.
A few things did happen though. Both my bikes (748/1098) basically got complete fork/shock refurbs about a year ago. Both had trouble on this shorter track, but for non-compliance through the bumpier sections instead of headshake. The big track (WSIR) we normally race on is pretty smooth and there is not a lot of hard braking. What I found by riding on the slower bumpier track was that I had way too much rebound damping on the shock. I have to admit that it is pretty hard to tell whether a problem is coming from the front of the bike or the rear, so this was an "a-ha" moment for me.
I sped up the shock (on both bikes) and the transformation was mind blowing. It seems that I am an idiot. I have reams of notes on what changes result in what ride quality, but somehow I guess I got the rear sort of planted on a fast smooth track, then focused all my attention on the forks and geometry, never going back to review my shock settings.
Once I did that, things got a lot better fast. I will let you know if this also solved the stability issue on the fast track next month.
On a side note, Michelin is sort of giving up on the WSMC, so I needed tires and put Dunlop's on the 1098. I kept the Michelins on the 748. Both bikes ran very well with the same overall settings.
 

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Bob, if you can get your hands on the new Pirelli slicks try a set. The new 200 is supposed to be the shit.

Also the current Dunlops are not what they used to be in 09, because they had problems with the compound. Tyre manufacturers may not use softeners anymore, which Pirelli started to do in 06 or 07 (when they were falling apart). The outstanding longevity of the "old" KR106 (758 and 6136 compound) front tyre is nonexistant anymore, which is really sad.

If you´re in the market for new rubber, try the Pirellis!
 

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Bob, if you can get your hands on the new Pirelli slicks try a set. The new 200 is supposed to be the shit.

Also the current Dunlops are not what they used to be in 09, because they had problems with the compound. Tyre manufacturers may not use softeners anymore, which Pirelli started to do in 06 or 07 (when they were falling apart). The outstanding longevity of the "old" KR106 (758 and 6136 compound) front tyre is nonexistant anymore, which is really sad.

If you´re in the market for new rubber, try the Pirellis!
For a trackday or endurance rider the new PRO slicks from Pirelli are the shit. Longgg lasting,sticky,and don't need warmers.Getting 3-4 trackdays out of a rear.
 

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Hey webman,

the 200 isn´t available as SBK PRO. See the following list:

Pirelli-Slick:
160/60 R 17 NHS TL Slick, SC2

180/55 R 17 NHS TL Slick, SC2 + Pro

190/55 R 17 NHS TL Slick, SC2 + Pro

200/60 R 17 NHS TL Slick, SC0 + SC1 + SC2

Metzeler, Slick:
180/55 R 17 NHS TL Slick, K2

190/55 R 17 NHS TL Slick, K1 + K2 + CompK


I just got off the phone with my buddy. He was pretty excited about the new slick. He said longevity was really good and the feeling was really good. He mentioned the remarkable feeling when it starts to slide. Might have to dig a 16.5" up if the Michelins aren´t good... which I highly doubt :D
 

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Discussion Starter · #19 ·
Hmm, this is interesting. I tried some Pirelli rain's this spring at a Laguna Seca track day. I was there, it was raining, and I decided that wasting the day was not going to be an option so I went out on rains. This turned out to be much more fun that I expected. Very weird having traction on wet pavement.

I was impressed and this almost convinced me to try the Pirelli's again. I tried them once in 08 on my 999, but could not get used to the squishy sidewalls and the way they rubberbanded into the turns. Are they better now? The Dunlops and Michelins feel good to me in this respect.

And I noticed that I never responded to rjjablo, I did have a crash Nov 09, and had to have the frame straightened and replaced the triples etc. I would say that this was probably part of the problem but since I have had good days since then I know the bike can run well when conditions are right. It is really bad when there is a side wind.

However, this did remind me to check the swingarm, which I did have out but I think I will look at it more closely. I have recently noticed that the eccentric is not moving around as easily as it should when I put a new chain on.

I had another friend comment that running a larger rear sprocket, which usually ends up with a shorter wheelbase, is maybe a problem. He is recommending that it is better to go with a gear setting that gives the longest wheelbase possible so I am going to try this. This is one thing about the 1098 I don't like as much as the 999.
 

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Eccentric

"However, this did remind me to check the swingarm, which I did have out but I think I will look at it more closely. I have recently noticed that the eccentric is not moving around as easily as it should when I put a new chain on."

Could just be a buildup of crud and dirt. Minimum I would pull apart and clean and inspect.

Key thing is to set your eccentric and leave it, and adjust your gearing by chain length and sprocket size. This will minimize your changing your ride height and swingarm length
 
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