Head shake/Tank Slap on deceleration

D

dgmontoya

Registered
Any ideas on what might cause this. it only happens when decelerating. while in gear andi let go of bars and coast it begins to shake and tank slap. i can simply grab the bars and stop it, but i would like to know why it is doing so i could maybe fix or prevent it. bike is lower about 1.5 inches and the fork springs are cranked down about 12-14 turns to hold my 260 lb ass. open to all thoughts
 
Front tire or possibly front brake issue.

Stop Letting Go of The Frigging Handlebars
 
Chances are you need to have your steering head tightened up or you may need to have the bearings replaced. Poor tire inflation can cause this issue as well but my bet is on steering head
 
rubber2burn said:
Chances are you need to have your steering head tightened up or you may need to have the bearings replaced. Poor tire inflation can cause this issue as well but my bet is on steering head
Click to expand...

When this happened on my CBXs it was the head bearings being a little loose. Hasn't happened on the Busa by 28,000 miles (thankfully).
 
CBXRider said:
When this happened on my CBXs it was the head bearings being a little loose. Hasn't happened on the Busa by 28,000 miles (thankfully).
Click to expand...

I have seen this same exact issue on a few busa's but I am with you it has not happened on mine either knock on wood :thumbsup:
 
It has newer tires on it. maybe 3000 miles and the bike only has 10000 on it. it is 2002. i will check the air. it has be doing it for sometime and i dont really remeber it doing it when it wasnt lowered or spring tightened, but i wasnt paying much attention then.
 
Not the bearings. Like said, it is most likely your sh!tdy stock tires, the weak viscosity in the steering damper.
 
Where did your stock steering damper go? Throw some gear oil in there after you fix the real problem... tire cupping, brake issue or lose steering head...
 
I had a front tire go out of round on me. It would do the same exact thing. Lift the front tire off the ground and spin it. If the tire hops in any fashion, it's toast.
 
Why would you want to let go of the bars during deceleration? Putting mild pressure on the bars is part of the design of sportbikes.
 
TruWrecks said:
Why would you want to let go of the bars during deceleration? Putting mild pressure on the bars is part of the design of sportbikes.
Click to expand...

Being that its a sportbike is not a requirement that you have to have both hands on the bars at all times. Maybe he was taking a breather or wanted to stretch. No matter why, the front end should still be stable, especially with a steering damper. Problem is, there are several possible causes for headshake.
 
dgmontoya said:
it has be doing it for sometime and i dont really remeber it doing it when it wasnt lowered or spring tightened, but i wasnt paying much attention then.
Click to expand...


Bingo!!!!!!!!!!!!!!!!!!!!!!!!

Lower the front forks 10mm and if that don't cure the problem, add another 10mm. You have your geometry all fookered up. Raise the front or lower the rear or maybe a little of both.
 
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