Busa Suspension Problem


M3T1

Registered
#1
Hey guys. I am new to this site and the world of Hayabusas, but I did just purchase my first one! I LOVE it! It's everything I had hoped it would be. It's a 2003 Busa with only 8,000 miles on it.

Now the bad news is that my new girl has a bit of a problem. When I hit 50 mph and up to about 65 mph, she gets REALLY bumpy. Bumpy to the point that my friend following me in his car could see my head bouncing up and down. One of my friends said my rear shock might just be too tight, but I figured I would post on here to see if you guys could shed some light on my situation.

Also, my busa is heavily modified, so I wanted to post the modifications here in case that would influence your assessment. I have an aftermarket triple tree and lowering links, and I am on the lowest setting of those links (about 4" lower than stock I believe). I also have a 12" extended aftermarket swingarm, with a 240mm rear tire. The wheels on it are the All Things Chrome turbo wheels. I don't know if any of this matters, but I figured since it's a bumpy ride issue, my stretched setup might have something to do with it. The thing is, I had a stretched GSXR 600 before this and never had any issues like this (that bike was lowered as well....albeit not as much).

Any and all advice would be greatly appreciated!

2013-06-08 13.48.33.jpg


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2013-06-06 18.13.49-3.jpg


2013-06-06 22.26.06.jpg
 

Samaki

Registered
#2
It is likely that the previous owner increased the preload in the rear when he lowered it to keep the tire from trashing the underside of the tail section. This is a common practice and will give a very rough ride. You should have roughly 1 1/2 - 1 3/4 inches of sag in the rear. Read the post linked below for information on how to take these measurements and make the adjustments.

https://www.hayabusa.org/forum/maintenance-do-yourself/89876-jinkster-attacks-suspension.html
 

Tufbusa

Track Coach / TufPoodle Coach
Registered
#5
Adjusting the sag (via preload) will have absolutely no effect on the ride. You can back off on the compression and possibly soften the ride. If that has no effect you either live with what you have or replace the spring. However, if you go with a softer spring you'll most likely develop tire clearance issues.

Jinkster's thread won't do you much good with your set up!
 

Poppy

Donating Member
Registered
#6
While I agree the compression might be the source of your problem, I would also have a trusted shop check the rear tire, or both tires, for proper balance. The mph range you mentioned just may be the un-sweet(?) spot. Not sure that's a word but I like it....:2cents:

Nice looking bike and welcome to the site!
 
#7
I haven't had any issues w/ my single sided swing arm +6 with the stock suspension but I plan to drop in the Progressive Suspension 465 Series as it was designed to compensate for the stretched arms.
 
#8
While I agree the compression might be the source of your problem, I would also have a trusted shop check the rear tire, or both tires, for proper balance. The mph range you mentioned just may be the un-sweet(?) spot. Not sure that's a word but I like it....:2cents:

Nice looking bike and welcome to the site!
I agree with checking out the wheels. I think a little more science goes into making wheels that why I went with PM, cause I know they test each of their wheels.
 
#9
I would definitely check tire balance but it sounds like you need to set the suspension up for your weight and set up. And PM wheels are all I use also.
 

1busa

Registered
#10
Great lookin busa :thumbsup: Very common problem when runnin 1 with a stretched arm. I think Rubb has a thread asking about the suspension setup for a stretched busa and 1 of the sponsors recommended an air ride set up. Might be the answer to your problem and a chance to add another custom touch to an already tricked out busa :whistle:
 

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