understeer on exit

[BrendonM]

bike is 07 600rr

im getting understeer on corners with hard accleration on exit.
Steers fine on entry but once i crack the throttle starts to understeer as i roll on.
if im slow on roll on mid corner the bike will situp

could turn in a little quicker
ride is a little hard
and ive got 25mm from cabletie to bottom of fork (giving me 15mm to play with?)
ive narrowed it down to

too hard front compression damping
ride geomerty(front riding to high)
to soft rear rebound
to soft rear compression damping

suggestions?

cheers Brendon.

[ninjaa]

Add a turn of preload. Few laps see how she goes

Have ya seen Marty or Russell to set everything up? Won't be the rear, unless it's spinning up on you?

Adding again Writing all your changes in a notebook? Baby steps, change too many things at once & it'll throw everything off & any progress you made
Harsh ride would be high comp, 1 click out, few laps, in pits & check again.

[Kowalski]

It's hard to set a stock CBR up very badly, the adjusters all have limited range. If your sure it's not you (turning in too early? missing the apex? not letting the bike finish the turn by holding on too tight?) I would check geometry (ie sag) and then shock dampening (not enough compression damping? Perhaps too much rebound?)

If you have 15mm of unused front travel (travel, not chrome) at Barbagallo it must be a dam stiff set-up. Too stiff perhaps, or at least out of balance with the rear.

[Neil-51]

The 15mm of chrome showing on the fork leg sounds normal.

I guess you mean it runs wide when you open the throttle??? Same deal on mine, but it isn't that bad. I have just gone to a ride height adjust in the rear and am going to try more height on the rear. I have only tried this setup at Collie and the bike is fine. Barbs is different, so will find out more next time I ride there.

[quattro750]

tis a honda
q

[CBillyR]

Too much preload in the front.
If you set the front up to for turn 7 it'll be too hard for the rest of the track.
Can't lift the rear much with-out the front starting to push, loss of stability and not use all of the front tyre.
07's > fronts aren't as logical as most people think.

DD

[BrendonM]

cheers for the advice will go a bit softer preload on front and see where that takes me first.

[bomoto]

Drop the front through the triple clamps or jack the back up a bit to steepen the head angle!!

[96]

Mostly good advice there (ignore kowalski though).

If I'm running wide, I add preload to the rear spring. Springs effect geometry, damping effects response and repeating actions. (think, put 200nm of force into a shock, it will compress 'X' mm. Turn up or turn down the Damping and it will still compress 'X' mm, just get there slower/faster. Make that spring harder though, and it will compress less)

I have a genuine 30mm (just measure it) of chrome left under my zip tie, and thats on a pair of .95 springs. We could put a 1.00 in on side to go a little harder. It rides awesomely too, so don't think that travel is the be all and end all.

If she wallows on exit (noticable in the basin) the spring is doing to much work and you need to increase the damping in the shock. If it snaps loose the suspension is not supple enough and needs damping removed from the rear.

(hint: fast bikes are stiff. Avoid going softer to set the bike to you, go harder on the opposite end and just work up to it, the balance should still be the same)

Ps, pirrelis?

[thro]

2 things:

- the forks don't compress all the way to the bottom.

- if you're typical aussie weight, you're too heavy for the bike's stock springs, like me, so its probably riding nose high to start with, and winding power on will cause it to run wide. I have/had the same issue.

I'm 90kg, and i need the rear shock preload wound all the way up and its still a bit low, sag-wise. OK for road use, but not track.

I've tried messing with winding on some more rear compression damping, more front rebound.... didn't help a lot - my guess is that to cure the problem you'll need heavier springs.


out of the box they are quite soft, which is great for soaking up bumps during road use, but no good for riding super hard.


As per the above, you probably don't want to soften the bike up if you can help it - they're already very soft - but I suspect you will be running out of adjustment on the rear unless you buy stiffer springs. I'm in the same boat, I need to run a fair amount of sag in the front at the moment (40mm or something) to keep the front/rear balance somewhere near right.

[Sean'o]

Have you measured and set up the front and rear sags? Standard starting point is 35mm front and 25mm rear rider sag. you need the right front and rear spring rates for your weight, see russel farrow(cant think of campany name) or russel speak(dynotime) once you have them right, set the sags. If you are using all your travel under brakes into turn 7, then you cant really soften the front anymore, maybe take a little preload off if you have the right springs in it. you could try dropping your forks throught the tripples a bit to sharpen up steering, or raise the rear ride height, but its all pointless if the springs arent right. if you are over 75kg and running a stock rear spring, it will be a little too soft, squatting the arse on acceleration, wich will cause the front run wide. Id be winding a bit more preload into the rear first, see where that takes ya, thats if you dont want to change springs.

[Arwon]

In a discussion with Andy recently he described what your saying would be a sympton of having the forks through the triple clamps too far. So too steep an angle on the front end. It may make it turn quicker on the way in, but it realy screws with the mid turn.

[BrendonM]

sags are set 35mm front and rear. keep in mind this is a street/trackday setup. im 75kgs with gear on.

perelli supercorsas (dual compound)

25mm of chrome showing to cable tie.

i would have thought pushing the forks through the triples would put more wieght on the front therfore helping to stop this problem? but dont want to do this if its a dampning/preload issue think it would have the best 'general' geometry from factory not for a specific track.

i have had the rear spin up and step out on exit a few times but only a little.

so add preload to the rear. next question is the c spanner in the tool set seems to be a few mm to big!!!??? and the wont budge with a hammer+screw driver. i must be doing something wrong???

[g0zer]

when i first bought my 04r1 bog stock it would stick the corner, but rolling on gas past apex it was possible to push the front tyre before spinning up the rear- im not sure if this is the same as what you mean, but it results in running wide on exit.

i never really understood the problem from a geometry POV, i just figured that the front didnt have as much traction as it should have and threw money at the forks. i had the suspension damping replaced with racetec internals and a little stiffer fork springs and dropped front ~10mm and the problem went away (well that problem anyway).

[96]

25mm rear sag is huge!

I've got no bike sag and maybe 10mm max rider sag.

[Neil-51]

The c spanner is a bitch to use. Unless the shock has been adjusted recently you may be pushing shit up hill. A hammer and screw driver will not work.

It is probably easiest to pull the shock out. This is actually quick to do.
1. remove the plastic hugger
2. undo the top and bottom shock nuts
3. put a diamond jack between the tyre and the exhaust and take the weight off the shock
4. pull out the top and bottom shock bolts
5. remove the shock

Use your c spanner to adjust the shock. While it is out spray the collar with CRC so you have a chance of making adjustments on the bike. I would suggest going up 2 steps on the preload.

[Neil-51]

25mm rear sag is huge!

I've got no bike sag and maybe 10mm max rider sag.

He said 35!

Ohlins suggest 25-40mm although you would aim for the lower end of that range for the track.

[96]

Re c spanner: there should be a piece of round pipe with one end flattened so it locates on the end of the c spanner. You should then be able to put the back of a hammer/breaker bar/long piece of metal, into that pipe, and get some decent leverage.

[thro]

^^ in theory, lol.

in practice if it hasn't been adjusted before, you'll simply end up rounding the end off the c-spanner, and have to get a grinder out to re-shape it repeatedly.



the stock C spanner on the 07s is made of cheese, at least mine was.

[Marty MOOSE]

If its a stock shock the adjuster is in a bad place they fill up with sand! put some Inox on it and tap gentle with a hammer to work it through then it will turn. Very poor Mr Honda.

MM