HiRob, Steering wobble into Cornwall, I'm not surprised, AS you know,(WHERE YOU BE TOO) is a common response from a Cornishman on meeting an outsider for the first time.( Means Where do live) Your bike wasn't keen on going into cornwall best not go there with her again lol, Craig,I had the same problem,a few years ago Tank bolts too tight so put thicker washers on. end of , I have always found the M20 very stable, Best spend time to sort this problem out, Take care , Before I got too old used to be able to stand on the saddle at low speeds, Andrew

email (option): warbikes@gmail.com

another dead cat then Rob

email (option): roger.beck@node6.com

Took me 2 days to find my problem: bent rear chain adjuster, allowed the axle to move but only when leaned to one side. Got itself back in place before I stopped.

email (option): sales@victorylibrary.com

Thanks guys. Good input. I dropped tire pressure from about 28psi f/r to 22f/25r. Seemed to help some. I might drop further to see how it rides. Also loosened tank bolts to be safe. Haven't elevated the bike to check steering play, but I suspect I may need to adjust or overhaul. I don't know the history on the steering head at all.

I can still easily induce the oscillation, but the bike definitely corrects itself if I stop encouraging the weave. I could ride hands free no problem, but it's still disturbingly easy to get it started with its weave if I get it going.

One follow-up question - I'm running a 3.6 tire on front, 3.5 in back. Since the spec is for 3.25f/3.5r I'm wondering if this could be part of the problem?

Craig

I doubt it Craig..I have run up to 4.00 tyres on my M20 front and back. I didn't like the handling with the 4.00 on the front but it didn't cause any problem as you describe. This is not a typical M20 problem.
I currently run 3.50 K70 'Gold Seal' tyres at both ends with about 28-30 psi in the back and 25-27 psi in the front and personally think it handles better at these higher pressures...specially so when loaded with camping gear...
I've run at these pressures for years without problems and haven't generally found M20s to be overly sensitive to variations in tyre pressures....
I suspect your problem lies elsewhere...Ian

email (option): ian@wright52.plus.com

Okay, thanks Ian. Looks like steering head is next. Damn, this isn't going to sort itself out easily is it...

What are the tyres, Craig ? Did they come with the bike ? It's certainly an odd combination - the 3.60 is a lower profile and the mixing of profiles and types is always going to increase the 'unknowns'.

If they're 20 years old, hard and have maybe been sitting flat then it might be best to fit a new pair so that you can at least rule it out.

How's your front fork spring and the fork action ? If it's sagging at the front on an already smaller radius tyre then I'd expect it to be more inclined to wobble.

The steering head is easy enough to check. Jack the bike up so the front wheel is clear and check for play at the bearings and that the forks can fall equally easily to each side with no notching in the races.

To check and adjust the head bearings. It's best to tighten up all the spindle bolts before you jack up the bike. That way you take out any movement in the spindles and keep the spring off the head stock. Once the bearings are adjusted you can slacken the spindle bolts to check for spindle wear. Ron

email (option): ronpier@talk21.com

You're right, that wasn't too bad at all, and I think I've sorted it out. Great tips on this thread, and as always it's easy to go through old posts to get the details on any given fix.

Steering head was in pretty good shape, but I snugged it up a bit just to be safe... but not too snug of course. The real issue was with the fork link spindles. All four were loose, and some embarrassingly loose I'd say Ooops. All tightened now as close to spec as I can get, and a short test ride showed great improvement. I'll know for sure after some more miles, but this may have done it! Thanks guys, really really helpful feedback.

By the way, tires are relatively new, and not too worn. I confirmed alignment is good, and wheel bearings are smooth and snug. Now I can see how fine-tuning tire pressure changes things, but I think it was the links.

p.s., do others use the 3 shakeproof spindle washers? Part No. 36-382? That may have contributed to my loosening spindles.

if you still have the wobble try changing the direction of the tyre take it off and turn it and put it back on

email (option): roger.beck@node6.com