GIXXER CHATTER

[Super Dave]

The longer swingarm on the current Yamaha's stems from the stacked gearbox.  But by doing that, they are able to keep the bike's Center of Gravity (CG) forward.  We can talk leverage ratios, etc.

[max@traxxion.com]

100 times out of 100 if the back of the bike is chattering on the way into the turn, it is the rider's fault, not the bike.  This happens to even the fastest top pros.  They are using the engine to stop the bike and not the brakes.  You have to stop more before you begin downshifting, and make more deliberate blips of the throttle.

This symptom is always followed by the statement "It always seems worse in the race".  Well, that is because you are trying to go a little deeper, and a little later on the brakes.

You need to retrain yourself to use the brakes to stop the bike not the motor is all.  

This is a particularly bad habit because if you are used to using your engine to help stop the bike, when you false neutral, you will freak out and end up in the weeds every time!

[Super Dave]

Interstingly, there are schools, not mine, that are advocating not blipping between downshifts.  I'll leave it nameless.  

Tried doing it a bit myself with no real gain or loss.  Was not able to completely incorporated it, so I can't say one thing or another.

I do, however, enjoy Ducati slipper clutches.

[Thingy]

 I do, however, enjoy Ducati slipper clutches.

I wonder where you tried one of those....

[DanO966]

100 times out of 100 if the back of the bike is chattering on the way into the turn, it is the rider's fault, not the bike.  This happens to even the fastest top pros.  They are using the engine to stop the bike and not the brakes.  You have to stop more before you begin downshifting, and make more deliberate blips of the throttle.

exactly

[max@traxxion.com]

Hey DanO, is your photo icon a result of such activity?  It looks kinda ominous when taken in the context of this thread!!! ;D

[DanO966]

ummm no chatter.  I just tucked the front end.  T4 BHF.  If I had better riding posture I may of saved it.  I thought that I did, I flat-tracked it all the way across the track...man crashing sucks...lol  But not only did Jack get the whole thing on film, I learned a whole heck of a lot from that little mishap. ;D ;D
Sometime you gotta slow down to go faster!
And yeah that's me rolling thru the sand...lol

[Bam55]

So when I set my idle higher to the point of me almost red lining just to match RPM's in one practice session with each blip of the throttle and it still seems to do it? By the way where has Max been while I been fighting the GIXXER chatter? You realize Max, you are the one that sales pitched me into getting rid of the Yamaha's and getting to the Suzuki's, up until mid-last summer I had not been able to duplicate any of the Yamaha times at any of our regional tracks. I finally went into the same times after finding out the fantastic Suzuki I bought has had a throttle position sensor limiting the bike to 80% throttle ::) completely open. (I know this isn't your fault Max but I have to say something in my defense)
   The way Max has pointed out "This even happens to the fastest top pros" makes meat head club racer P.J. feel pretty secure that he can fix this with hard work. Thanx MAX!!!

 Pat Thornton
  MW/GP  Ex #55

[max@traxxion.com]

Hey, PJ, are you sure that the 80% TPS was an electrical part?  Couldn't it have been the loose nut between the seat and the handlebars?  HAHA!!!  Just kidding!!!

That sucks bad that it took so long to find that problem.  Electrical SUCKS!!!   >:(

[max@traxxion.com]

Take note that if your are a REALLY top pro, this becomes a non-issue, because this is the exact problem slipper-clutches fix.  You just come in, hand your bike to your pit crew and then ask your lead mechanic to add in some slip and reduce the engine breaking effect applied to the back tire during decelleration.  Problemo Solvedo. 8)

[Bam55]

The loose nut between the bars a seat will ALWAYS be a problem,or least as long the wife doesn't discover lock-tite!
 The guys at Mid-Cities Motor Sports (West Bend,WI) dicovered it on a Dyno,did some changing, holy cow this thing will dust my R6's now! I hopefully can determine if my "chatter" is the loose nut for sure now.
 Max, do you agree with Dave and I in our theory of the chain adjuster by being so close to the front making negative geometry under hard brakng though? If not, what is the difference if you have the same gearing with different length in the chain adjusters and where the wheel is in geomerty? And what does this do in difference under braking, entrance speed, and exit speed? Lots of questions for you, at least I'm not asking in June though!

[max@traxxion.com]

The only effect moving the wheel would have is that the closer to the pivot you move the wheel, you would have less leverage, and thus a stiffer bike.  But anytime you change your gearing, you need to reset your free sag to 10mm.  Same thing with ride height.  

Stiff springs and slow rebound aggravate this problem, and unfortunately, when left alone, racers always crank away like idiots on both of these two things.  I NEVER move spring preload once I set free sag.  You should always use AS LITTLE REBOUND AS POSSIBLE.

The problems with Americans is that we are trained to think "more is better" and with suspension, that just isn't true.  You can't just crank everything up and go faster.

In fact, we try and "idiot-proof" our suspension here so that even when cranked up by someone who doesn't know what they are doing, at least they won't kill themselves.