||06-17-2009 04:37 AM
I'm not saying anything is impossible, but it seems unlikely to me that an engine oil designed for motorcycles would cause clutch slippage. Oil manufacturers know that most motorcycles use wet clutches, so the friction modifiers that go into automotive oils don't go into motorcycle oil. But bear in mind, I don't work for an oil company, and I don't know everything about all the motorcycle oils out there - or even very much, for that matter. Then again, it's possible you grabbed a motor oil, albeit for V-Twins, but still intended for dry clutches. If you really think it was the oil that produced your clutch slippage, I'm afraid I've got some bad news, because though I'm not sure what you mean when you said you flushed the oil, but unless you tear your engine all the way down and clean everything, oil is going to remain in your engine, period. However, I'm not sure how much of the friction modifiers it would take to affect a wet clutch.
You said you got a new clutch, and the problem persisted? Was this before or after you changed your oil? If it was before, it's possible that the problem was indeed the oil, and the friction material on the drive plates of the clutch absorbed the modified oil. It would really behoove you to find out as much as possible about the oil you were using when you first noticed the problem.
All I have at home is my '09 manual, and all it sites in troubleshooting for a slipping clutch is insufficient clutch spring tension and worn friction discs. Did you install the new clutch yourself? Did you have to put it together? If so, is it possible you built or installed it incorrectly?