High speed 'wobble' issues?...

[sargeomatic]

Does anyone have any suggestions as to what to look into (besides correct tire pressure) for remedy of high speed (75+mph) instability on my '83 R65? I'm riding with Bridgestone Spitfires, using a 100/90 18 on the front instead of the 90/90 called for by the manufacturer - could this be part of the problem? Any good comments/suggestions would be appreciated. Thanks. -Sargeomatic

[Justin B.]

[movedhere] Chit-Chat [move by] Justin B..

[nhmaf]

Well, the 1st and easiest thing to do is to check the tire pressure.   On modern tires, pressures are/should be generally higher than those posted on the antiquated stickers under the seat or in the old manual.
Make sure that you have at least 32 PSI in each - I generally run 35 PSI.

Also, visually inspect the rims for dents, cracks, lost wheel weights or other damage.

Next item is to check steering head bearings, swingarm bearings, and wheel bearings.   To check the wheel bearings, grasp the wheel at 3 oclock and 9 oclock position and push/pull on opposite sides trying to wiggle the wheel on the axle.  There should be no play.  Rotate the wheel 90 degrees and try it again.    IF it has been a long time since you've serviced the wheel bearings, it may be time to go in there and clean/inspect/regrease them.

The steering head bearings are checked by ttrying to wiggle the steering head fore/aft and left/right (not turning the handlebars.
Also, check to see how easy the handlebars turn from left to right.   IF the bearing preload is correct and the bearings are in good shape&greased, with the bike on the centerstand the handlebars should just gracefully turn to either side starting from the centered position with just a nudge on either handgrip.  If they flop over hard against the stops, or don't easily turn all the way - the grease is probably hardened up and they need to be cleaned/inspected/relubed/etc.  
Many people forget about their swingarm bearings - these also need periodic lube/clean (perhaps once every few years) and they have large lock nuts which must be torqued to help set the proper preload.
Like the wheel bearings test, there should be NO side-side play in the swingarm and the gaps between the swingarm tube and the insdei of the frames should be roughly the same distance.   You'll need a thin walled or ground down 27mm socket to service the swingarm bearings.  Steering head&swingarm bearings = regular grease, wheel bearings=high temp wheel grease

[nhmaf]

Also. just check the bolts that hold the engine to the frame - make sure that none of them are loose.  Also check the bolts that hold the rear shock absorbers on the frame/swingarm.   Lastly, check the bols that hold the rear subframe on to the mainframe.

IF going throuh all the previous items, more or less in the order presented, fails to solve the problem, you may need to look into new shocks at the rear of the bike and/or checking the springs and servicing the front forks (springs sometimes break or develop a "set", old fork oil or low fork oil level reduces dampening and can contribute to steering control issues on bumpy surfaces.

[montmil]

I run Spitfires on my 1981 with a 100/90 up front with no issues. carry about 30-31 psi in the front tire. No wobbles.

Check wheel balance and all the other good ideas from NH Mike. Simple stuff first, then confirm the more challenging checks.

Welcome to the home of all things R65. We love folks... and photos!

Monte

[Semper Gumby]

Hi  sargeomatic,

The thing that got my handling under control was:

1) Making sure the wheel bearings are tight and smooth.  No side to side play and no clicking or 'roaring' while you are on the bike.  If the wheel bearings are bad you can usually feel something is wrong when you are in stop and go traffic and the bike seems to wander at slow speed ( <10mph).

2) Making sure the steering head bearings are tight and have complete freedom of movement from stop to stop.  Get the front wheel off the ground. And move it from stop to stop. If the bearings are greased properly the whole assemble will want to go to the stop.  If there is any stiffness here then clean and grease.  If you fell any 'nothchyness' in the bearing then replace 'em.  Also grab the front forks and push/pull forward and aft.  There should be no movement.  If you feel even a slight click then your steering head bearings may be loose OR your front forks may be worn out (also a problem).

3) The thing that did it for me was making sure the swing arm bearings are in good repair and are set to the tightest setting of the torque range the manual gives for these bearings.  Please remember though that the torque for these bearing is quite small.  The pivot pin has an initial torque setting of 15 ft-lbs (20n-m)* to get everything in place and then a final torque setting of 7-9 ft-lbs (10-12 N-M).  Set this to the max value 9 ft-lbs (12N-M).  Do not confused the pivot pin locknut with the pivot pin itself.  Many have made the mistake of setting the pivot pin to the locknut setting of 80 ft-lbs.  This setting will destroy the swing arm bearings.  

It is this item 3 that most improved my high speed handling -- Not the larger front tire (which helped a bit), not the Telifix fork brace.

If you still have high speed wobbles and you aren't running a fairing and or pannier/top case then-

4) Look for cracks in the frame or a bent frame/forks.

Good luck.

(*Clymer R-Series 1970-1989 - page 593)

[steve_wicks]

tyre wear can also do wierd things to directional stability

[drewboid]

Do you have a wind screen / fairing or saddle bags? They will often cause a high speed problem.
How about your riding position? Upright in the wind blast - loose jacket flapping in the breeze? tucked in on the tank?

Does this problem show up all the time - straight road as well as curved?

[clouseau]

I was able to lessen the wobbles by switching from high handle bars to the LS handle bars.  
Actually it was a pleasant side effect since I just wanted the LS handlebars.
My mirrors don't stick out as far anymore, so maybe that was a contributing factor.
Try going for a ride without your mirrors on and see what the difference is.
I would assume if both mirrors aren't adjusted equally, the wind gets deflected differently on either side creating an imbalance.
Also, by changing both tires to a Metzelers, things seem more stable.