Kickstart pulls down on take off...

Headfullofsnakes · May 10, 2011

I have looked through previous posts on this forum and I know that the problem here — my kickstarter pulls down when I accelerate away from a standstill — is supposed to be the layshaft bearing, a bush, or a the layshaft itself bbeing not quite straight. BUT... I've stripped it all out twice now and bearings and bushes are sweet, the shaft itself is pretty sweet (within 2 thou), and it's still bloody doing it!!!???

I thought about this more recently and it occured to me that this problem started the exact same day that I fixed the clutch. I thought the cable had broken, but actually the clutch operating lever body had come loose. I removed the outer cover and tightened it (with a hammer cause I don't have the right tool, and cause I'm a bloody amateur!), put it back together and went for a ride. I was happy with the clutch but noticed the kickstarter pulling down...

That was a year and a half ago! Could I have something in that outer cover set up wrong? the spring? I've looked and looked and can't see any problem!? I want my bike on the road again. Help?

Josh Cox · May 10, 2011

Sounds to me like the spring has not been fitted properly.

When the kick start is vertical in the stowed position, there is still quite a bit of spring force holding it up.

When I put mine together, with the kick start pinion pushed in most of the way, you engage the spring, then turn the pinion around past the lock. The kick starter sits in its static (up) position with about half a turn of force from the spring.

On the inside of the middle cover there is a little metal latch that holds the rachet locked away into the pinion, when in this position the spring is holding it there under force.

Keith1069 · May 11, 2011

Had same problem for years despite new bearings and k/s bush. My bike uses a '57 Dominator shell and came with Dommie inner and outer covers with the weaker spring. Changed to Commando parts and the k/s still moved down in 1st. So, I took a close look at what else could cause this and found witness marks on the end of the k/s (where it sits in 1st laygear). These corresponded with the 2nd gear dogs where they come through the gear in 1st. Now, I can't remember exact dimensions (was a few years back) but basically I shimmed the 1st laygear enough to move it to the right and away from the dogs. There was enough clearance between the layshaft shoulder and k/s end face so it didn't then bind on the gear inner face. It solved my problem but yours may be something else.

ILLF8ED · May 11, 2011

Headfullofsnakes said:
I have looked through previous posts on this forum and I know that the problem here — my kickstarter pulls down when I accelerate away from a standstill — is supposed to be the layshaft bearing, a bush, or a the layshaft itself bbeing not quite straight. BUT... I've stripped it all out twice now and bearings and bushes are sweet, the shaft itself is pretty sweet (within 2 thou), and it's still bloody doing it!!!???

I thought about this more recently and it occured to me that this problem started the exact same day that I fixed the clutch. I thought the cable had broken, but actually the clutch operating lever body had come loose. I removed the outer cover and tightened it (with a hammer cause I don't have the right tool, and cause I'm a bloody amateur!), put it back together and went for a ride. I was happy with the clutch but noticed the kickstarter pulling down...

That was a year and a half ago! Could I have something in that outer cover set up wrong? the spring? I've looked and looked and can't see any problem!? I want my bike on the road again. Help?

Sounds like the classic layshaft bearing failure to me. Has this been replaced with FAG roller bearing. The original bearing will fail no what the taste (sweet).

Headfullofsnakes · May 11, 2011

Yeah it's not the bearing, it's been pulled apart twice now and had a new bearing even though the one in there (roller type) was fine.

I've also, since posting, put a new kickstart return spring in. It's set up right but yeah no change. The old spring seemed fine, will keep as a spare!

Will look for evidence of 1st laygear problem though? See if there's witness marks on the kickstart shaft? Hoping to get into it again in next week or so, and will see what it's looking like there.

pete.v · May 12, 2011

Headfullofsnakes said:
Yeah it's not the bearing, it's been pulled apart twice now and had a new bearing even though the one in there (roller type) was fine.

I've also, since posting, put a new kickstart return spring in. It's set up right but yeah no change. The old spring seemed fine, will keep as a spare!

Will look for evidence of 1st laygear problem though? See if there's witness marks on the kickstart shaft? Hoping to get into it again in next week or so, and will see what it's looking like there.

Do you have end play at the kickstart shaft? Some tend to over shim due to the radius on the shaft where the shims sit against or just because they think the that no play is good. Others will go the "no gasket" route which is fine but will also close up the play. Better to be sloppy in this regard. 10, 20, 30, 40, 50 thou, to big whoop. As long as you got some.

Headfullofsnakes · Sep 12, 2011

PROBLEM SOLVED:

Ok so eventually I pulled out the whole gearbox and took it to an engineer here, who is also a Norton man. He pointed out that the mainshaft hole in the inner gearbox shell was slogged out and not even round any more. Hence a lot of movement of the mainshaft and sleevegear bearing spinning in that hole. He wasn't sure that'd be the problem causing the kickstart issue, so he also went through my layshaft and found a couple of bushes that were supposed to be floating had actually been locktited in. This done it was reassembled and is now on the road. I've done a good 300 miles now and all seems well. My guess is that that mainshaft hole was so out of shape that the whole mainshaft itself was able to twist and put unusual pressure on the layshaft which would then bind with the kickstart shaft.

This has been a massive learning curve for me! But I feel I am getting to know my gearbox and primary a lot better, which feels great. Thanks to Alastair Mears, John Taylor-Leigh, and to this forum for help with this! Great to be riding again.

Phliper00 · Oct 12, 2013

I have the same problem... My layshaft bearing seems ok. What would you recommend? Buy a new main shaft and layshaft or go to a local mechanics and get the job done?

Kickstart pulls down on take off...

Similar threads