Clutch

[LjR]

I’ve been struggling trying to get the clutch adjustment properly. The problem I think is I have no clearance on the actuator. There is no play on the clutch arm at the engine. All plates and corks are moving freely. I went back to 4 plate clutch to see if the stack was too high. I’ve measured plates and corks. All good. I feel like something is sitting too proud. I’ve now removed the sprocket and all to make sure all was assembled correctly. It was. I’m out of ideas. Please help.
Thanks

[Warkton Tornado No.1]

If all the components are of known quality, that is the only realistic starting point. Worth reminding anybody that a thick as possible chain-case gasket helps whilst usually more likely to be re-useable.

I will confess that the last time I got ‘caught out’ wondering ‘WTF!’ was because an SIL clutch bell supplied with the motor, was actually distorting under simply the load from the clutch springs! Once I replaced it with a decades old Innocenti bell (my preference being the older type to suit the centre bored gear cluster) the clutch was excellent. For the record, that set-up utilised CamLam six green friction plates with their thin steel plates, a modified Innocenti non-solid 46T sprocket (deepened slots) a set of strong springs (checked that they didn’t get coil-bound) all running in ATF. No drag or creep & no slipping.

One last thing. As far as I am concerned, the commonly held wisdom of having the actuator arm at 90° is something best ignored. IMO there is less angular movement at that geometry. It only takes a rough sketch on the back of a fag packet to show that if the actuator arm is set rearwards to something approaching, say, 60°rather than 90°, there will be more angular movement for the same pull at the headset lever. ‘Every little helps’

[Tony Hart]

I would look at your clutch bell (spider). I have two where the relative height of the circlip groove is too high allowing the corks/steels to sit closer to the actuator. This results in little or no movement on the clutch arm before the clutch functions. When hot and under load this can cause clutch slip. I also have another clutch bell that is too tall to get the side case on at all. As mentioned above a thicker chain case gasket may solve your issue or if your spider also has the circlip groove machined too high you could try source an original Inocenti clutch bell.

[LjR]

all parts are innocenti original. I did check the height of the circlip grove. seems the same as another spiders I have. I did remove the sprocket to make sure all was good there, and it is. I agree something is sitting proud. Thanks for the input. Any other advice is appreciated.

LjR

[Warkton Tornado No.1]

I would look at your clutch bell (spider). I have two where the relative height of the circlip groove is too high allowing the corks/steels to sit closer to the actuator. This results in little or no movement on the clutch arm before the clutch functions. When hot and under load this can cause clutch slip. I also have another clutch bell that is too tall to get the side case on at all. As mentioned above a thicker chain case gasket may solve your issue or if your spider also has the circlip groove machined too high you could try source an original Inocenti clutch bell.

I filed to mention that particular problem as detailed, but I am aware that it can exist. Although on any clutch set-ups I have built from scratch - & had the benefit of utilising OEM Innocenti components - the accuracy of the interaction of all the parts - within achieving the required ‘geometry’ - has ruled out any problems.

The cure for inner bells (spiders) that have their circlip groove machined too highly can often be by selecting the thickest (3 mm as far as I am aware) top pressure plate or even placing another ‘normal’ steel plate beneath the top pressure plate. However, I will empathise that the manufactured sizes of the inner clutch bells can vary wildly compared to OEM Innocenti & any spring set should always be checked by compressing in a vice to ensure that coil bound they are not restricting clutch function.

It’s becoming increasingly difficult to find first class components for sale & even old hoarders - like me - find that wear & tear takes it’s toll. Circlip grooves can wear & if there is one criticism I would have for the clutch design even from new is the circlip itself. It’s not a hardened steel product & it loses it’s ‘spring’ over time. Next time I build a clutch using OEM components, I have a few ‘proper’ internal circlip that I had surface ground down to the correct thickness.

[LjR]

I put all back together and there is some play. very little. its not hitting the thimble at least when side cover on. shifts nice and no slipping. so I will ride for a while and see what happens.

Thanks for the input!
LjR