650ed wrote:
Nessism wrote: ...........BTW, what kind of oil did you use? A motorcycle oil that damages clutch plates would be extremely unusual. Only oils with friction modifiers do that.
Excellent question! Ed
To expand on this, there are plenty of oils that are not JASO-MA but will work just fine. Just because an oil has not been tested for compliance doesn't mean it won't work. There are many people who swear by Shell Rotella in motorcycles, and that's a heavy duty diesel oil.I've never tried it personally, it's not JASO-MA, but it is very well tested.
Best to go for a JASO-MA oil to be certain. My first KZ - a KZ250 - had a slipping clutch that would also drag when cold. The oil was definitively wrong when I got it. Changing to a motorcycle oil fixed the drag, but could still get clutch slip.
I eventually replaced the plates and springs (I bought a full kit), however both the springs and plates were still within service spec. I'm pretty confident it was the incorrect oil sitting in the engine for such a long time that had the clutch slipping. New plates and springs, and I could wheelie that little 250 by releasing the clutch too quick.