Front end bump / jittering.

[headshrink]

Close to being done with my restore project, just working out the bugs and fine-tuning the carbs.


PROBLEM:
I don't know if I'm using the proper terminology, but I've noticed the front end feels a bit jittery, or bumpy as I travel down the road. It isn't a side to side movement, but rather an up and down jitter/bump/vibration.

At first I ignored it, thinking I was just used to the feel of my CBR, but when I ran it on the freeway it was obvious that it wasn't the way it used to be. In fact, on the freeway it was annoying and I could tell it would cause premature rider fatigue if left uncorrected. I mentioned this to my brother, who rode on it last weekend, and he said it felt funny to him too. He is a new rider, so everything will be new to him, but it did help confirm I'm not imagining it.

RECENT CHANGES & THEORIES:
1) My bike was stored in my garage for about 2 years, and I know some people can develop flat spots on their tire. HOWEVER, a majority of this time I had the bike raised on paddock stands. Also, I've put a couple hundred miles on it recently, and would expect it to work its way out (it did when I got a flat spot on my SUV). The tire is a Sport Demon, appears to be in good condition, and was at proper PSI.

2) Right before putting my bike in mothballs I replaced/upgraded the steering head bearings with a tapered set. My engine blew 2 miles from home on my first test run, so I never really got to confirm it was all good, but felt fine for that brief ride. This is why it was in mothballs the last 2 years (and I got another bike). I just jacked up the bike and tightened the steering nut a bit, and did another test run. The front-end feeling is still there.

EDIT: 3) I had a low speed low-side the very first turn on the very first ride after putting the new engine in, so I wouldn't have had a chance to feel anything strange.... other than the ground. The only notable damage was a foot-peg, and I checked fork alignment by loosening the bolts, bouncing, tightening. I don't think this is the problem, but still worth mentioning.


Your thoughts, ideas, advice???

[Motofool]

Originally Posted by headshrink

........... Your thoughts, ideas, advice???

It seems to be an out-of-round perimeter of the tire.

I would lift the wheel in the air and check roundness with against some fix reference.

Observe the rubber lines next to the edge of the aluminum rim.
Those indicate if the bead of the tire is uniformly seat, by keeping exactly the same distance from that edge all around, on both sides.

[headshrink]

Originally Posted by Motofool

It seems to be an out-of-round perimeter of the tire.

I would lift the wheel in the air and check roundness with against some fix reference.

Observe the rubber lines next to the edge of the aluminum rim.
Those indicate if the bead of the tire is uniformly seat, by keeping exactly the same distance from that edge all around, on both sides.

It seems I see a wobble on the top when I spin it. I suppose more miles won't work that out?