Forum

[Tim NZ]

You may like to confirm that the eng and clutch sprockets are indeed BOTH the correct 'pitch'? Wrap the chain fully around them...


Not all sprockets are well made, and either one may even be eccentric to a degree, or even the same pitch?





As an aside, I was left scratching my head recently, having trouble fitting and adjusting a new rear chain, to eventually discover that the gbox sprocket was not for a #530 chain, but was in stead #428!


How long that bike had been ridden with mismatched chain and sprockets is any ones guess.

[TonyBax]

Hi Tim, I will double check that. I haven't sent off for another sprocket yet as I'm going over the bike seeing what else is needed and put (hopefully) just one order in for parts. I'll keep you posted, cheers, Tony.

[vince]

Hi, if sprockets are correct size and the centre distance is 9inches then logic dictates that the chain must be too short. As you stated that its a trials replica I thinking that the 25t sprocket has been retro fitted with the original shorter chain. Vince.

[TonyBax]

Hi, chain is correct length for 25T engine sprocket, 90 pitches, but, I did check the pitch of the chain versus the sprocket and chainwheel. Fits the chainwheel perfectly, but it doesn't fit the engine sprocket ! Once the chain is halfway around the sprocket, it isn't in the dip it's riding up the teeth. And looking at it from side on, you can see the teeth are wider than the chain pitch.
I am assuming that it's the sprocket that is wrong, as that may have been made for a different bike altogether, ( or did they fit a larger chain to other models ?). The chainwheel looks to be an original item, so I am fairly confident that I should have it sorted by simple ordering a new engine sprocket.
Any more thoughts ?
Thanks again for all the input.
Cheers.

[TonyBax]

Hi, chain is correct length for 25T engine sprocket, 90 pitches, but, I did check the pitch of the chain versus the sprocket and chainwheel. Fits the chainwheel perfectly, but it doesn't fit the engine sprocket ! Once the chain is halfway around the sprocket, it isn't in the dip it's riding up the teeth. And looking at it from side on, you can see the teeth are wider than the chain pitch.
I am assuming that it's the sprocket that is wrong, as that may have been made for a different bike altogether, ( or did they fit a larger chain to other models ?). The chainwheel looks to be an original item, so I am fairly confident that I should have it sorted by simple ordering a new engine sprocket.
Any more thoughts ?
Thanks again for all the input.
Cheers.

[TonyBax]

Sorry, finger stuttered on posting and I doubled it up - can't see an 'edit' or 'delete' button.

[vince]

Hi, is the sprocket a spline or taper fit? Vince

[TonyBax]

Hi Vince, it's a spline.

[Mark M]

Maybe you have a Metric size chain? Might explain why it sits on a large sprocket but not a small? Also l think Greeves used crank sprockets nearly identical to Enfield but without the shoulder on the back. REgards, Mark

[Tim NZ]

Early clipper eng sprocket.