ZX10 front end shake - trackday - why?

[R650R]

Its obviously an engine issue. With a ZX10 being ridden hard the front end should never be on the ground long enough to tank slap ;p

[R650R]

Seriously though with the track conversion from road what tyres are you running now??? I remember my GSXR being dead stable on road tyres but with proper triangulated track/race tyres it scared the shit out of me at Pukekohe and became a liability on the road....

[Big Dog]

Seriously though with the track conversion from road what tyres are you running now??? I remember my GSXR being dead stable on road tyres but with proper triangulated track/race tyres it scared the shit out of me at Pukekohe and became a liability on the road....

And what bits came off? Enough to affect the weight bias?


Stupid phone / Tapatalk, apologies in advance.

[jafa21]

It's not so much the shifting of gears, but poor control inputs in general. When someone is too rough with gear shifting, they typically tense up and grip the bars and go stiff in the arm.

Flap your wings bro and loosen the claws.

Edit: And all that mechanical shit above.

i think this is very possible. I have noticed i am not that good with gear changes (up and down). I try to do it too fast and violent and end up screwing it up.

[jafa21]

DON'T TAKE ANY ADVICE FROM CASSINA - SHE'S A FUCKING IDIOT.

What you're describing is that the bars want to shake or weave when the front gets light. This can be from a number of causes, ranging from the personality of the bike, to incorrect tyre pressures, bad tyres, loose bearings, rear wheel out of alignment in the swing arm (don't trust the marks, they're almost always out), too much ride height in the rear (look for spacers), worn headset bearings, forks that are mis-aligned, wrong fork oil heights or weight, front wheel bearings, or even a bent frame or swing arm.

Then, there's the rider inputs as described above. Your position on the bike can also affect the situation.

ZX10R's are generally pretty lively anyhow. I would seriously advise talking to one or two people - Robert Taylor being the top of the list given that he's pretty good at this stuff, Shaun Harris being the second on this list. This is beyond the understanding of your average mechanic.

I also have high trust in the better track day instructors to look at your riding style. Two different riders will get two different views of the same bike if their riding style or weight are different. I prefer a quicker steering bike that allows me to slide the bike - my set up is the complete opposite of my best riding buddy and neither of us can ride the other's race bikes without changes (he's old and far too intelligent to ride like I do). The point is, get the bike set up correctly by someone qualified. Get your style checked out by a coach.

MBB.

i will get an instructor to look at my riding next time i am on the track and also possibly get Robert Taylor to look at it. He is doing a seminar soon at spectrum.

[jafa21]

There was a thread on this a few weeks back (tank slapping it was called) and a guy even posted a video discussion that modifying a bikes suspension can be a cause. Could you not look up the internet to find out what mods work for your particular model of bike? I would find that out first perhaps before employing anyone to do mods they think will work. Maybe some models of bike are more suited to mods than others and you may need to buy another bike.

this is very odd advise. BUY A NEW BIKE????

[jafa21]

Cassina - please go away.

Two points - how old is the rubber on the bike ? The late hyper sport stuff is very tyre sensitive.

And the old standby - get someone else to ride it who knows what they're doing for a second opinion.

Tyres were bought about 9 months ago. The manufacturing 6 months max before that. I have done approx 3500kms on them which include 4 track days. They tyres i am running are Dunlop Q3s. I dont think the tyres are the problem. (according to my limited knowledge). They seem fine and are always stored in a garage with no sunlight. Although it spent about a month at spectrum. They usually store the bikes outside and it has been very hot. Can one month in the sun make a difference?

[jafa21]

Hyper sport? Yes, even tyre pressure will have an effect, as will tyre temps...

Good advice.

i run 30/30 tyre pressures. I dont have tyre warmers. I usually warm them up in 1-2 laps.

[jafa21]

Yesterday I had a couple of wobbles out of turn 6. Seems my bike wobbles a bit more with sport tyres on when im a muppet with upshfts. I relaxed a bit and it settled.

But thats me on my bike. Op should be talking to RT or someone in the know.

mine happens after turn 5 on the back straight. happened twice and no other place.

[jafa21]

To the OP.
Does it do it on every 3rd to 4th gear change? Or just that specific place in the track? If so, please describe that area of the track. Seal change? Camber change? rough area of seal? In short, what makes that part of the track different? Would help for possible analysis.

it only happend at my last track day after turn 5. back straight. its pretty flat. i am in second gear at turn 5 and i speed up violently and change to 3rd and change to 4th. i think my violent change could be the problem. but that i thought was a given. Because i am accelerating very fast the front sort of comes up and gets light. (the front didnt actually come up). And then i get a shake. I think this is the only place i am accelerating the hardest. I thought the steering damper revalve solves that issue.

[jafa21]

Describe the two crashes after getting the suspension done. Are we talking couple of low impact slides or bigger crashes?
What did it hit and id it roll etc.

ENJOY

Crash 1 - lowside - turn4
https://www.youtube.com/watch?v=RiWRuadMM2g

Crash 2 - just before turn 5
https://www.youtube.com/watch?v=xmb7...ature=youtu.be

[Big Dog]

it only happend at my last track day after turn 5. back straight. its pretty flat. i am in second gear at turn 5 and i speed up violently and change to 3rd and change to 4th. i think my violent change could be the problem. but that i thought was a given. Because i am accelerating very fast the front sort of comes up and gets light. (the front didnt actually come up). And then i get a shake. I think this is the only place i am accelerating the hardest. I thought the steering damper revalve solves that issue.

Dampers dampen.

If you set it so firm as to never have any wiggle at the front steering becomes difficult and under the circumstances you had a head shake before you get a squirming from the rear instead.

That energy has to go somewhere.


Stupid phone / Tapatalk, apologies in advance.

[jafa21]

go back to basic's first thing is string line the bike, checking the square of the front tire to the rear.
check for tire stagger ( the bike generally crabs with this issue )
check suspension linkages ( and pivots for play )
check headstock play

Just because a Reputable bike shop has checked doesn't mean they know what the fuck they are doing.

i totally agree that bike shop looking at it doesnt mean anything. I am not capable to check the above things. Any suggestions on how i can get that done. or get a independent opinion.

[Reckless]

it only happend at my last track day after turn 5. back straight. its pretty flat. i am in second gear at turn 5 and i speed up violently and change to 3rd and change to 4th. i think my violent change could be the problem. but that i thought was a given. Because i am accelerating very fast the front sort of comes up and gets light. (the front didnt actually come up). And then i get a shake. I think this is the only place i am accelerating the hardest. I thought the steering damper revalve solves that issue.

Possibly the wheel isnt straight ahead when the weight goes back on it because of your gear change action??

[jafa21]

Could also be that the rider has undergone a little modification.
More aggressive now this is track only?
A bit stiff after 2 crashes?
Rider lost / gained weight?
Spending more time in attack mode?

Sometimes when a rider complains about head shake
In particular corners or at particular speeds you can see them waving their throttle arm between gear shifts like a chicken trying to achieve flight. When you see it you can see all that input translating steering input.


Stupid phone / Tapatalk, apologies in advance.

i could be more aggressive at the back straight - very possible.
i think i might be bit stiff after the crashes.
i havent gained or lost weight.

i do feel its my input thats making it like this as it doesnt happen everytime. but i thought if i get damper revalved no matter what i did the damper will prevent from shaking.
The above comment probably sounds stupid to some. but i dont know what i am talking about so i thats why i am asking here