Swaying

'79 KZ650 B3

Cruising along at 35-40mph in 5th gear when the bike suddenly starts gently swaying, requiring constant, slight steering corrections. After a short time, it quit. I thought it might be a flat tire, but everything was ok. It's happened several times.

I'm wondering what it might be, and how I would go about tracking it down.

sounds like possibly swingarm bushing/bearings.block up bike with back tire off the ground and see if you can move the back tire from side to side.

Strange that it would suddenly stop but check (for your safety) tire pressure, steering stem bearings, swingarm bushings. Have you had either tire/rim off lately? Also very possible it could have been irregularities in the road surface?

Post edited by: Bluemeanie, at: 2008/02/07 12:55

Bluemeanie wrote:

Strange that it would suddenly stop but check (for your safety) tire pressure, steering stem bearings, swingarm bushings. Have you had either tire/rim off lately? Also very possible it could have been irregularities in the road surface?<br><br>Post edited by: Bluemeanie, at: 2008/02/07 12:55

I thought about the road surface, and re-road the same section after it quit. No swaying.

Tires are at 40lbs.

Neither tires or rims have been off lately.

How do you chekc the steering stem bearings?

sit on the bike hold the front brake and rock the bike back and forth.while looking down at the nut that clamps the tripple trees together.you are looking for movement between the nut and the tank.

Or for a closer look, with bike on center stand have someone else sit in passenger area and let bike settle on rear tire (front tire now off ground). Now go grab both forks and feel for ANY movement.

could these possibly be cause of "swaying"?

front shocks are leaking and low on oil, or rear sprocket loose on hub?

on checking the rear fork bushings, will the rear shocks need to be disconnected to get an acurate feel?
and how much movement is too much?

jim

Seems odd that it would stop too. A quick check of the head and swing arm bearing/bushings should confirm or eliminate those items. Also check your axle nuts for tightness. None of these items though would tend to self correct IMHO, so I'm a bit puzzled as well.

I wanted to say stop making a pit stop at the local watering hole, since one would expect the swaying to go away as you sobered up! :laugh:

Sorry I couldn't resist! :evil:

40 lbs. of air? I can see you maybe getting away with that in the rear (specs call for 32 - 36), but that seems way way high for the front (specs call for 28.) These specs are for the '77 KZ650, so I guess it's possible that things changed when they switched to tubeless tires. I would adjust the air pressure to specs and see if the problem ever happens again. Ed

Post edited by: 650ed, at: 2008/02/07 19:39

original pressure was at 28 to 30 before increasing to 40.

jim

My '80 F1 calls for 28F/32R, I run 30/35 and works and rides great. 40 seems way to high, don't think it would cause swaying.

My 77 650 has been swaying due to worn bushings for the back swingarm.

Looking for replacement junkyard parts to amend quarter inch of lateral movement at the chain adjusters. I'll keep posting progress.

In '83, My Dad's car had a bad "stablizer" (sp) shock on a 77 Monty Carlo that would allow strong front wheel shimmy from 30 m.p.h. that would abruptly stop at around 40-43 m.p.h. Smooth as silk. Something about centrifugal force or whatnot? I wonder if there could be corelation to Jim's swaying issues with possible looseness or worn parts.

Post edited by: Qdude, at: 2008/02/08 17:12