Gen 3 chattering/harshness

2618 Views 15 Replies 5 Participants Last post by mochilo123, Aug 15, 2017

mochilo123

Discussion Starter · Aug 13, 2017

Hi all!! A month ago I purchased a 08 Kawasaki ZX10R (3rd gen) as an only-track bike. It has some goodies, *brake pump, fairings, 520 transmission, front and rear revalved, etc.*

The day to test the bike arrived, *it was in Cheste, Spain.* Sunny day, warm, 30+ celsius degrees.*

Dunlop KR106 comp. 1 front, kept at 2.3 bar during the whole day

Bridgestone V02 medium rear, kept at 1.7 bar.*

I started adapting myself to the bike. The thing is, *when I wanted to push a little, the bike chatters as hell, it feels harsh mid cornering, and that obviously keeps me away from riding hard.*

Previously I had put new fork seals and new ohlins 1309 oil, 490ml/leg as per manual.

First I thought the rear was topping out and that was causing the chattering, *but I took a good amount of preload away and that didnt solve anything. Then I thlught i could have poored too much oil in the fork, *but I checked and its ok. Also tried closing rebound rear, nothing. I have to say the front rim has a hit, *and the sidewall is bent. However no air is lost, *nor does it vibrate in straight line or releasing the bars. It was balanced without problems. The hit is on the right side, *and chattering happens on both left and right handside corners.*

Dynamic SAG is 27mm front and 25mm rear. I send you a video where the chattering can bee noticed and some pics of the tyres.

Has there been a case like this? I have heard this bike is pretty difficult to set up suspension wise, but I think this is not normal.

What could you recommend?

Here is the video

https://youtu.be/mZ7hs89U7d0

Thank you very much!!!

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Honey Badger

· #2 · Aug 14, 2017

My first guess - your tire pressures are a bit off. On the Dunlops here in the US, if my pressures are off just 1-2 pounds for the temp and pace the bike will chatter all my fillings loose. Proper pressure at the proper pace and it smooths right out....

Newf

· #3 · Aug 15, 2017

I've tested the same dunlops on my s1000rr and hated them because of the same chatter issue and because I race on Pirelli I just didn't want to waste the time to find the best suspension setup so I went back to Pirelli. Got the tires for cheap was the only reason I was using them.

I don't pay much attention to SAG numbers anymore just mostly go by how the bike feels but 27mm total SAG is very hard. Also, not sure where mechanical bottom is on the Gen3 forks but it looks like you have a lot of travel left, so you might need less preload or lighter springs to start with.

I did notice that the chatter went away when I reduced the hot tire pressure from 2.4 to 2.2 but then I started to rip the front tire. I think Dunlop have a smaller setup window then Pirelli for example and tire compound has to be correct for the track or you'll find it very hard to get a correct setup.

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Carlos76

· #4 · Aug 15, 2017

Stiff V02 rear shakes sometimes, I run it 1.5bar hot and 2 clicks softer compression compared to Pirelli slick.
Other than that: Loose fairings, too much front compression damping, too tight chain, steering head bearings.

mochilo123

Discussion Starter · #5 · Aug 15, 2017

Thank you all for your answers!!!

I have also read that these Dunlops it quite difficult to get a good suspension setup. Perhaps the rigidity of the carcass requires more work from the suspension. So the conclusion regarding to tires is that stiff carcass tires are not the best options for this bike? I read that this bike is pretty stiff, and that may require softer tires.

Regarding to sag, fully extended fork I get 139mm between the lower foot of the fork and the dust seal, plus some mm of the topout spring, that makes around 142mm of space, and the full travel according to manual is 120mm, so I think im not far away from the bottom.

Next trackday I will swap to pirellis FR+RR and check the steering head bearings, as well as the chain tension.

Did you have the same chatter as in the video??

Thanks again!!!!

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LDH

· #6 · Aug 15, 2017

27mm of rider sag in the front?

Sag is a mathematical equation of overall stroke? You want to be in the middle 1/3 of the available stroke of 120mm of fork travel so you should be around 38-40mm of rider sag.

mochilo123

Discussion Starter · #7 · Aug 15, 2017

I have already tried less sag front, less sag rear, nothing solved the chattering.

I brake really hard. If I wasnt using the whole travel I wouldnt have that sag...

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mochilo123

Discussion Starter · #8 · Aug 15, 2017

Its stiff ok, but I have tried less sag... Nothing

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LDH

· #9 · Aug 15, 2017

Brake dive should be controlled by the damping not the spring rate or sag. Sounds like you have a poor set-up that you are trying to band-aid with unorthodox settings and that never works especially on a bike like the Gen3 ZX-10R that doesn't handle that great to begin with under the best circumstances.

mochilo123

Discussion Starter · #10 · Aug 15, 2017

Spring supports, damping assists

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LDH

· #11 · Aug 15, 2017

Well shit, if you are the expert why you asking us? It's not like any of us here do suspension for a living or anything...

mochilo123

Discussion Starter · #12 · Aug 15, 2017

No man, but I have tried more front SAG and was the same chattering... Not saying you dont know anything

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LDH

· #13 · Aug 15, 2017

Just givin' ya grief bro

The bottom line is you need to get the basic set-up correct first & foremost before you begin you start trying to alleviate the chatter issue. Moving sag numbers into areas they are not supposed to be in order to compensate for blowing through the stroke etc is not going to give you the results you expect. You have to get the basics right first. Depending on your pace you may just not have enough suspension to get the job done. What kind of lap times are you running at Ricardo Tormo?

mochilo123

Discussion Starter · #14 · Aug 15, 2017

With this shit chattering I could do a 1.49.

What sag would you aim for?

Thank you!!

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LDH

· #15 · Aug 15, 2017

That's basically 20 seconds off the lap record. Most Intermediate riders could do that on a bone stock ZX-10R and you should not being having any chatter problems at that kind of pace. As I mentioned previously I would start back at the basics again. Make sure the ride height both front and rear has not been tampered with and then reset the sag.

Shoot for 38-40mm of rider sag in the front

For the rear I would personally start at around 30mm of rider sag. I have seen riders at or near race pace run less, but at 20 seconds off the pace you are likely not doing yourself any favors by doing that especially since we actually lower the rear ride height by removing 4mm of spacer at the shock mount to correct the geometry and aid in drive grip. Keeping the bike taller in the rear with less sag is not what I would normally suggest on this particular bike.

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mochilo123

Discussion Starter · #16 · Aug 15, 2017

Lol man 1.30 was motogp record, I dont know who you get around with. I know very good riders who ride 1.45-1.46, I dont know what you are saying mate.

I will try different tires, pirellis, I will try also different sag if that doesnt cure it.

Thx for your help

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