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Model 10 clutch and counterweight


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Hi folks. Any help would be appreciated please.

I have recently acquired a model 10 engine that seems to have the wrong clutch or counterweight, this is causing a problem because the sprockets don't  line up for the primary chain. I think that the problem is with the counterweight, as i think the clutch is correct. It is located on its shaft with a woodruff key, but not 100% sure. If any model 10 experts could chip in it would be appreciated.

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The M10 has the double weight as standard but these are interchangeable with the single weight as the fit on the crank is the same - as long as it has the same pitch and teeth number. Your problem looks to be the basket which is sitting too far out. There is a top hat spacer that sits in the oil seal on the mainshaft and the basket and hub sit up against the spacer and when fully home the sprockets line up. There looks to be something sititng behind the basket in your picture?  Is the correct spacer fitted.


It's easy to see if the front sprocket is aligned as the tensioner wheel should be in direct alignment with it

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Many thanks for your input. The clutch as far as I'm aware is fully home, it's located onto the woodruff key. I will have a look later. It's good to know that the counterweights are interchangeable Woody, I was wondering how difficult it would be to change it if need be.

I wonder if anyone has any photos of the area in question to clarify things a little. 

It is my understanding that there are two different clutchs on the model 10...?

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Has the woodruff key been pushed backwards and is sitting partly up in its slot which is preventing the huib and basket fully locating. That basket is too far out, the outside edge should be somewhere near in line with the edge of the weight

The only thing behind the hub should be the top hat spacer which locates in the seal

You really need to pull the clutch off, remove the key and push the hub on to ensure it sits right up against the spacer

Weights are generally interchangeable as long as the number of teeth and pitch is right as they differ on some models. I have a weight from a much later M158 engine on my M10

I'm not aware of any difference in clutches on M10 but someone else may know differently


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I didn't get chance to have another look this evening due to work commitments. I am however sure that the clutch basket is fully home as it is up against the engine casing, not actually touching just a small gap. I have assembled with and without the woodruff key in place with the same outcome.

 There were 2 different types of clutch on a 4 speed

one type used inner square tabs on the inner steel plates with square fitment on the hub and outer pressure plate

the other type used rounded tabs - so the later 5 speed plates can work

This is info from Pete at in motion.


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Mine is an early bike so has the square tabs, wasn't sure about a different clutch on later 4 speed engines

From your picture it looks as though there is something sitting between the casing and the basket. I can see the raised boss to the left but next to that is something else (immediately to the left of the basket teeth in the picture)  what is that as it sits directly in the line with the crank sprocket, which is where the basket teeth should be

You can tell straight away if the crank weight is in the wrong position as the tensioner wheel should be directly underneath the teeth, otherwise it would miss the chain


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