I'm gradually getting there with the tuning of my Atlas and one of the things I've noticed as I've progressed is that the engine is becoming more powerful and responsive. Along with that the clutch has started to slip a little, but only until the engine has fully warmed up. Once it's at operating temp the clutch seems to works fine.
The pushrod isn't binding and the springs all seem ok and are adjusted correctly. When I rebuilt the bike I did quite a bit of work on the clutch to get it into good shape. i.e. I removed the notches on the splines, cleaned up all the plates and checked that they were all flat and also that they slip into the housing without snagging, fitted new cush rubbers, etc.
The primary chaincase has w20 oil in it and is filled to the correct level.
It wasn't doing this a week or so ago but as I said, the engine definitely seems to be running better now and it's got more grunt, I can feel it.
Hi Graham - Do you have a…
- Log in to post comments
Slip Sliding Away
A mistake sometimes made by Norton Twin owners is to put modern oil in the primary cases. This can contain 'friction modifiers' which will act like tiny ball bearings and allow the mating plate faces to slip instead of grip. Only use oil which is suitable for wet clutches.
The other common issue is that ........in order to get the plates to grip well, this generally means the three clutch springs have to be screwed well in. Usually to the point where the shaft heads appear almost level with the adjuster screw heads. This helps cure clutch slip but can lead to a heavy lever action.
Thirdly....... are your clutch springs the correct type? The early Dominator springs were long and thin sectioned. The SS springs were not as tall but made of chunkier wire. See attachment.
Finally as Howards asks......have you got the correct clutch for your Atlas model? The earlier Dominators had clutches with just 10 plates and the Singles even less.
- Log in to post comments
I never counted the clutch…
I never counted the clutch plates but there were a LOT of 'em. They were flat were in good order once I'd cleaned them all up. There was no room in the basket for any more, that I do recall. Pretty sure I put them all back in the correct order.
To be honest, it feels like a springs issue to me. I don't think the old ones in there are up to the job any more. They're screwed in all the way to the top of the threaded bolt.
With new 106 jet needles and new D needles in the carbs the engine is producing a LOT more power and it kinda feels like the clutch is now straining to control that extra bhp. It improves after ten minutes riding though. Don't know why that is but it eventually stops slipping after a while. I put w20 fork oil in the primary chaincase. Maybe it IS the oil that's doing it and after a good thrashing the centrifugal force spins it off the plates and the heat dries it out a bit?
This engine has high comp pistons and electronic ignition. It may well have a sports cam too but I haven't had it apart so can't comment on that.
- Log in to post comments
Hi Graham - Do you have a full set of eleven plates in your clutch ? howard