gs450 feels like gyro scope

[moondawg]

'80 450gs
New Avon 110/90 rear 90/90 front, progressive springs, new brakes... Springs and Avons helped a bunch...but,
Sometimes my gs feels like it leans back and forth, from side to side, like a gyro scope. The previous tires were so trashy and squirrely that it probably did this and I just didnt notice. A friend of mine who is a knowledgable mechanic said its a function of the 18 inch wheels. Has anyone noticed this characteristic on their bikes? Granted Im not the most experienced rider but I know when something feels a little funky... Nature of this beast?
This puppy runs great and this is the only slightly puzzling thing that keeps it from being a really great ride.
could it be the clubmans? I like the feel and look but would a slightly less radical set of bars help?
I had the headset bearings checked and they are ok.
Thanks!!!
moondawg

[txironhead]

I don't care if it has 32"'s on it, it shouldn't feel squirrelly.

I think it's a matter of tracking and alignment. Take the bike off of both stands and have a buddy hold the bike upright with the front rim perfectly straight. Then lay two known straight items (angle iron is the best but use what you can find, even PVC pipe will work if it's rigid enough) against the back tire. Since the back tire is wider than the front, this is our reference point. Now measure the gaps between the straight object and the front tire. The two measurements should be the same. If it's not, then something is askew with the bike. This could be anything from incorrect spacers, worn bearings, bent forks, etc.

If the measurements are the same, (and even if they're not), use a plumb to determine a perfect vertical line. Use the backbone of the bike (take the tank off if you have to) to make sure the frame is perfectly aligned with the plumb mark. Now eyeball the tires. Are either of the tires out of line with perfect center? If they are, you could have worn bearings, bent frame or swingarm, etc.

This is basically the poor man's way of truing a bike, and I've corrected many a "wobbly" bike in this manner. Most of the time it's a bearing or a wheel spacer installed in the wrong spot, but once we had to take the bike to a specialist to straighten the frame. Turns out the bike had been in a collision and the PO didn't mention it. Probably knew the frame was tweaked and ditched it as fast as he could. But that's worst case scenario.

[txironhead]

I just remembered that the symptoms started with the new tires. Check and see if the tires seated properly. Look closely at the tire/rim junction and see if there are any gaps. Also, there is a seating "mark", basically a ring cast into the tire. Make sure that the mark is a uniform distance from the rim around the entire circumference. Faulty seating of a tire can also cause instability, and can often be very hard to spot. Also, did you get the tires balanced? A lot of people will swear that you don't need to balance a motorcycle tire, but it's actually more important to do so on a bike than on a car.

[chiphead]

If your steering stem bearings are to tight it will definitely cause this type of symptom. Try losing the spanner nut a bit ands see if it makes a difference.

[Dink]

New tyres and fork sprinks, kewl. What about rear shocks?? were the tyres balanced??

Dink

[hp1000s]

Went through that whole deal with my bike...steering head bearings..lube & correct pre-load.

[moondawg]

The headset bearings were supposed to be checked but I dont think the mechanic did it... Another reason to DIY...I'll check again tomorrow. As far as the preload goes Im not sure what your talking about. I know about setting it for the Progressives but I guess Im clueless if your talking about the headset bearings... So THERE is a reason NOT to do it myself... Let me know what youre referring to. I havent redone the rear shocks yet. I read about the Seca turbo shocks but am open to other suggetions too. Hagones? anywho.... huge improvement so the rears well make it even better. Thanks for all the input everybody and keep it coming, I'll let you know the outcome.