Bike unstable off throttle above 60 mph.

[Doc_V]

Like the title says, when I'm riding above 60 mph, the bike feels unstable everytime I let off the throttle; it gets worse the faster I go. It doesn't do it when I'm accelerating, even above 70mph. I've have new tires, and yes, they are properly inflated. It did it even before I got the new tires.

Thanks in advance. I appreciate the input.

 

[DannoXYZ]

Are tyres balanced?

 

[Maddevill]

Define what you mean"unstable"
Headshake ? Slow weave ? Vibration ?
Things can be caused by different problems.

Mad

 

[Doc_V]

Yes, tires balanced.

No head shake or vibration; it just feels like the bike is squirming around under me.

 

[buellistic]

What kind bike? Year? Make?

 

[ST Guy]

Tire tread pattern, most likely.

Wait, it did it before the new tires? Then I'd look at your steering head bearings, wheel bearings (front and rear), fork bushings and seals, rear swing arm bearings, in that order.

Do you have ball or tapered roller bearings in your steering stem?

 

[Doc_V]

Bike is a 2006 Yamaha Roadstar 1700. Steering head bearings are roller. In the past 18 months, they've been replaced, along with the front wheel bearings and swing arm bearings. Forks have been rebuilt too, using all new seals, etc. Everything was fine until 2 years ago when I took a trip up to Oregon. A week before the trip I had a new tire put on the rear but the shop that mounted the new tire didn't replace the valve stems, like I'd asked, and I got a flat from a leaky valve in the middle of BFE Oregon. I had to leave the bike on the side of the road and hitch a ride, so I wasn't there when the tow truck driver piked it up, but it was clear he'd dropped the bike while loading it in the back of his toy hauler. In addition, he over tightened the tie down straps, bottoming out the forks and damaging the steering head bearings. He brought the bike to a dealership in OR, and when the tech tried to install a new tire, he discovered the rear axle was *bent* because the shop who forget to replace the valve stems also left out the inner wheel spacer. This caused the axle to turn in the frame, frying the wheel bearings and friction welding the axle to the alignment spacer. That's when the rear wheel bearings, spacers, axle, etc. were replaced. The bike has never been the same since and I'm running out of ideas.

 

[Maddevill]

Holy crap. The dealer basically fucked over your entire bike. Maybe take it to Gerry Piazza and get it checked to see what else is bent.

Mad

 

[cheez]

I was going to say "check steering neck bearings, rear shocks and shock bushings" along with "check tire pressure and balance" but it sounds like your problems are deeper than just checking for bearing or bushing wear.

+1 to the "take it to an independent pro and have them evaluate it and recommend fixes." Rob at Meteor Motorbikes in Emeryville might be able to help.

I'll be frank with you; that bike is worth about $4000 on its best day (more/less depending on mileage/farkles.) You're likely to spend several thousand chasing these issues out of it. It may make more sense to find another of the same year/make/model and just port your accessories over to it. Keep that path in mind when looking at the estimate and choose wisely.

Good luck with the repair. I'd be going back to the shop that did the rear tire with this story and asking what they'll do to make it right, personally.

 

[ST Guy]

Yep. Either take the bike to a professional chassis/suspension place for an evaluation. Or sell it.

If you go the professional route, be sure to tell them EVERYTHING.

(Which you should have done in your first post, by the way.)

 

[Busy Little Shop]

You might have experienced a deceleration shimmy and it's normal...
some bikes may shimmy decelerating through the 45 mph range... keeping
your hands on the bars should arrest most of the front end shimmy...
some bikes shimmy more than others and it's no big deal with your
hands on the bars in the critical speed range... your bike should be
immune at speeds above 45 mph...

Deceleration shimmy is chiefly the product of non OEM or a worn
tires... it ain't the product of tire cupping... but low pressure or
loose steering head bearings defeat the tire's corrective efforts...
because every bike has this instability... it is held in check by
damping forces created mainly by the tire's self-correcting
tendencies...

First sign that your steering head bearings are loose will be felt
through the bars as a pronounce clunk during braking...

If your steering head bearings are too tight the bike will weave and
not seek it own center...

 

[motomania2007]

I can't say this is what's wrong with your bike but I can tell you on a bike that I helped a friend resurrect 20 odd years ago that had a similar issue with the rear axle. I'll cut to the chase and that the way we got that axle out was we took a sawzall and cut it out but when we got it out the wheel bearings were shot and it had bent the swingarm on an old steel swingarm. So we pulled the swingarm out to check the bearings on it and actually on that swing arm it didn't have bearings it had bushings. But in the process we just decided to put a new swingarm in it because we were pretty convinced anyway we could measure it that original swingarm look bent. Sounds like you may have the same problem.

I definitely agree that you need to take the bike to frame shop and have them do some measurements because I'll bet something is bent and misaligned.

 

[Doc_V]

Thanks for the input guys. I'll give Meteor a call. FWIW The shop that screwed my bike up was Cycle Salvage in Hayward. I wasn't going to mention their name, but the more I think about it, other riders should probably know. I did talk with the owner when I got back. He tried to deny responsibility, but after a long discussion, he finally agreed to split the cost of rear wheel repairs. It barely put a dent in the total cost of my expenses, resulting from his tech's screw up, but there wasn't much I could do about it.

 

[Maddevill]

Well, they did turn your bike into Salvage, so ill give them that.

Mad

 

[Lucytriple]

I was going to say "check steering neck bearings, rear shocks and shock bushings" along with "check tire pressure and balance" but it sounds like your problems are deeper than just checking for bearing or bushing wear.

+1 to the "take it to an independent pro and have them evaluate it and recommend fixes." Rob at Meteor Motorbikes in Emeryville might be able to help.

I'll be frank with you; that bike is worth about $4000 on its best day (more/less depending on mileage/farkles.) You're likely to spend several thousand chasing these issues out of it. It may make more sense to find another of the same year/make/model and just port your accessories over to it. Keep that path in mind when looking at the estimate and choose wisely.

Good luck with the repair. I'd be going back to the shop that did the rear tire with this story and asking what they'll do to make it right, personally.

As an aside, guess what Rob did? Close up and haul off to San Diego

 

[Doc_V]

As an aside, guess what Rob did? Close up and haul off to San Diego

Well that sux. I couldn't remember the name of his shop and just came to this thread to get it, so I could look up his number give him a call. Oh well... Any other suspension guys in the east bay?