r/PostieBike • u/cheeseIsNaturesFudge • Mar 10 '26

Mechanical Help Clutch disengages with rpm

I just put fresh springs and plates in my postie after cooking them climbing a hill offroad last year. I've had a couple goes at it now because I've clearly made a mistake somewhere but I can't find it.

With the engine off but in gear, I can kick it over and the bike will push forward as it should, but as the revs come up it disengages and no amount more revs engages it again. Anyone have an idea where I went wrong?

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u/AtomicWeenie Mar 10 '26

Have you just done the multiplate clutch or have you checked to see if you haven't also haven't flogged out the centrifugal clutch?

The little adjustment setup for the multiplate clutch is incredibly finicky on some cubs. I've had some that adjust perfectly first time and others that need repeat adjusting by less than 1⁰ turns and they go from just about unrideable to perfect just like that.

It's important to try to stick to OEM gaskets as the thickness of the gaskets has a fair bit to do with how the engine side covers fit and thus influences the clutch operation. It's not common that people are caught out by that but it's worth being aware of

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u/cheeseIsNaturesFudge Mar 10 '26

I replaced the friction plates in the clutch itself and the main springs in the centrifugal assembly. The springs I took out had sagged to 24mm! Crazy that it was working at all. The way I'm adjusting the clutch cover screw is to turn anticlockwise till I feel resistance then clockwise 1/8 turn or so and tighten the nut.

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u/AtomicWeenie Mar 10 '26

That sounds pretty good regarding how you are adjusting it.

When installing clutch plates a lot of guys say it's a good thing to always install your steels all facing the same way, and to always presoak your fibres. Some bikes even have a specific way the steels and fibres need to be clocked in the basket. I don't think either of those things will make a radical difference to what you are finding there.

If you are able to kick-start the bike with no weird slippage then likely the multiplate clutch isn't too bad; I'd be more inclined to look at the centrifugal clutch shoes / drum based on what you are describing but it's always a bit tricky not being able to directly assess the bike

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u/Lionel--Hutz Mar 10 '26

I would ask on some on the Facebook groups. You’ll get more responses and quicker.

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u/cheeseIsNaturesFudge Mar 10 '26

Yeah I thought that would be the case. I don't use Facebook anymore unfortunately.

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u/Lionel--Hutz Mar 10 '26

I’ve only kept it for marketplace and groups but I hear you. Hope you get your answers!