Bike pulling to the left...

baz said:

The MK3 front wheel is different from the earlier models

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The bearing lock ring is different that's it.

cash said:

The bearing lock ring is different that's it.

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I assume it's a different hand thread?

baz said:

I assume it's a different hand thread?

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just a clip

johnm said:

My 1974 Mk11 Roadster pulled hard to the left for years. Was also a headshaker above 80 mph.

Finally fixed it by stripping to bare frame and going through the World's Straightest Commando article.

One quick check which may work is checking your wheel rims are central to the front forks and rear frame. For vibration through the bars make sure the front wheel is properly balanced. And isolastics are not set too tight.

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I am in full agreement with Johnm to check the alignment of your wheels.It doesn’t take that long.All you need is a long straightedge. I also use a glass plate on the fork tubes (thanks Greg Marsh) to check that they are parallel.
Mike

cash said:

The bearing lock ring is different that's it.

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It's a while since I replaced my front rim and re-built it, but I think there were two differences?
- the offset might be different
- I may be wrong, but when i asked for advice, before respoking the wheel, Les (LAB) pointed out the spoke pattern is set up to ensure the correct spokes are in tension when the brake is applied. In my mind I'm remembering, to achieve this, the mk3 spoke pattern is different (opposite way round?) to the earlier disc braked models, because the disc is on the other side.

Happy to be corrected.

I bought my Mk3 in 1993ish and it was and still is fitted with a Mk1 or 2 front wheel without issue.

YING said:

I am in full agreement with Johnm to check the alignment of your wheels.It doesn’t take that long.All you need is a long straightedge. I also use a glass plate on the fork tubes (thanks Greg Marsh) to check that they are parallel.
Mike

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i also 2nd the string method mentioned

acotrel said:

Common practice is to loop a string line around the front and rear wheel and line them up. If you space out the string line at the rear of the rear wheel, you can turn the steering to get the front wheel centralised and in line with the rear wheel. If it does not line-up, move the rear wheel to get the front of it equi-distant from the string.
When adjusting the rear chain, If there is a draw adjuster, I usually count the number of turns and adjust each side equally. But you need the wheels in line first.
Is is possible, but not likely that you have a twisted swing arm or frame.

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It's not unusual for a commando to pull to one side mainly due to the vagaries of the ISO setup and manufacture
If you think about it even a few thou out on one side of the gearbox cradle to crankcase could throw the swing arm/back wheel out of alignment
Even the head steady could pull the motor over one side or the other if it wasn't perfect
Add in the fact they are mostly 50 years old
Wheels possibly rebuilt slightly off etc etc
The good thing is it doesn't seem to affect a commandos handling in my experience
High speed weaving tends to be more tyre size width and condition related

baz said:

High speed weaving tends to be more tyre size width and condition related

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Agree, I'd like to add tyre pressure can/will cause weaving.

In my case, I chased high speed weave for a while, thinking that it had to be isolastics. I tightened them until the handlebars and footpegs buzzed. I finally added more air to the rear tire and that fixed it. I concluded that the issue was excessive sidewall flexing, because the 2.15 rim that the tire was mounted on was not the optimal size for that tire... Adding air stiffened the tire enough to control the sidewall flex.

Granted, that's only mildly related to pulling left with your hands off the bars.... My bike doesn't track perfectly straight with hands off the bars. It's not terribly bad, and my tires are well aligned. I've never messed with trying to "fix" it.