Sorry Two Tired, I attributed your question about timing to Bob...
I don't think the symtoms change after an oil change..I'm about to do that, so I'll let you know. I've been using Honda GN-4 oil 20/50. My clutch doesn't drag, but in really hot weather, it clunks when I shift, the hotter, the harder.
Would synthetic oil help? Plugs: I've been using NGK DR8ES.
If you look at my question about point life, I think My points may be on the way out...what do you think?
Chris
I don't get it, seems like Bob's timing is fine... But, then I've never put a strobe on him either.
I tried the HP-4 10-40W Synthetic blend in my CB550F out of curiosity. I noticed smoother shifting that seemed to improve over the next 200 miles. And well, the whole motor and transmission just seemed to work smoother. This surprised me, because I really didn't expect to notice anything different as the bike only had 9K miles on it at the time. I was really more interested in making the motor last as long as I could, and felt the best oil would work toward that. Perhaps it was a psychosomatic effect, but it didn't seem so at the time.
The CB750 has a different trans design that I have often heard of as "Clunky" when compared to the cb550. I haven't ridden my 750s enough to give a really good evaluation on that. But, during that one brief ride home, I was a bit concerned about the lack of smooth shifting (K8 motor in an F2). You might want to try an oil change cycle with the HP-4 for you own evaluation. It is more expensive, though still cheaper than a new bike, engine, or trans.
Logically speaking, a thicker oil would have a larger fluid coupling effect in a wet clutch, and add a bit more preload on the transmission during shifting as, in effect, the clutch won't disengage as much as one with thinner oil between the plates. Multi-vis oil is supposed to behave like thicker oil as it gets hotter.
I'll echo Bob's comment about the spark plug and add that, the heat range is correct for that motor. I was concerned you might be running a D7 which would be a hotter spark plug that might help combustion temps to become high for your motor.
If your points are "way out" this will effect the timing. And, as stated, advanced timing can increase engine temps. You might consider checking the timing as it is now before refurbishing the points, just to see how far it has drifted.
Cheers,
