Clutch Great running motor has a knock with the clutch in

[Motorbike Wanabe]

Hi Folks,

I was out riding this weekend and noticed that my engine has a knock, but only when the clutch is in and it is coasting. It runs great and there's no knock at idle or if you rev it with the clutch disengaged.

I can also replicate that same knock by removing the clutch cover and putting a flat-head screwdriver into the slot on the shaft in the small gear and turning it back and forth. Now, my first thought would have been that a bearing or bushing would be going out but (going from memory here and I'm 2500 miles away from the bike right now) it seemed that I needed to turn the shaft about 1/2 rotation to connect with whatever it is causing the knock. That would be way too much play for a bearing or something, wouldn't it?

I was thinking that it is probably some play between two meshing internal parts but, I'm trying to figure out what parts. These things aren't powering the space shuttle! I don't want to hurt it but, I've not found the source of the noise either. Any help is GREATLY appreciated.

 

[AussieSteve]

Some engines have a fair bit of backlash between the gears.
Also, when the clutch is disengaged, the driving plate, (with 82 teeth), wobbles around a fair bit.
On top of that, your clutch might be adjusted with a little too much plate clearance when disengaged, allowing the cog/plate to wobble slightly more than usual.
You've greased the primary gears? If not, a light smear of grease on each will help a bit.

Nothing is clipping the casings or cover?

... Steve

 

[Motorbike Wanabe]

Yup, I've greased the gears and checked and could not find anything that would cause a problem. I'll give it another look this weekend. Thanks.

I found it hard to believe that it could run this good and be that bad. It's only if I'm moving about pedaling speed with the engine running and the clutch disengaged. Then it knocks. I figured it was something with a lot of play between two parts but I'll check it out more when I get home.

Thanks!

 

[Motorbike Wanabe]

Well, just for an update, I put some grease on the gears again and pulled the clutch lever and rod out and greased everything up there as well. I've heard of folks pulling the clutch cable mount and squirting grease inside the housing. I don't want to hose my clutch disc with grease but, I like to keep things running for a long time also. Any thoughts on that?

With the amount of grease that I put in the clutch assembly, it seemed to quiet everything down pretty well. it was really clanking pretty hard if I had the clutch in and coasting down a hill. Felt like it was going to break something. It seemed to get worse as I slowed down, coasting. The grease seemed to help it. I'll be changing my rear tire soon and I might try a few other things to continually quiet this thing down more. I'm likin it!

 

[AussieSteve]

Just keep those primary gears greased - they need it regularly because they throw grease off easily.

On the 'grease in clutch adjuster hole' topic, be careful.
I read the same suggestions early on and packed that area full of grease. It took about 4 rides/disassemblies/cleans with brake cleaner to clean up the clutch and stop the grease oozing. Also means re-greasing the hidden ball race in the clutch, again without using excess grease.
A little under the clutch cable adjuster might be a good idea, but, as I say, be careful.

... Steve