Running great - if only my plug color wasn't freaking me out

[Mike Mullins]

Possible air leak somewhere ? (just a thought) Advance springs OK ? (just another thought)
Mike

[rzgkane]

My son still reminds me about swapping the R75/5 for an RD 400 because it wouldn't start when warm, when all it needed was the exhaust valve clearance opened up about 0.001.

Wow. Does .001 really make that big a difference on these bikes? Crazy.

How did you find out that was all it needed. The new owner call you and rub your nose in it or something?

[Jlovvorn]

I wiggled the cam and it seemed good, as far as I can tell.

It must be an air leak.

Going to try the other carbs and see what happens.

[Mike Mullins]

rzg: no, the new owner was pleased as he could be with it. Actually, I later made the acquaintance of an old BMW rider, who told me that if you set the exhaust clearances to factory spec, the bike would not start hot. When hot, the valves would expand just enough to lose compression: when they cooled, then you had compression. He said the bike had to make just a little valve noise to run right, and another 0.001 would have probably fixed it.(Thats where I got the 0.001 number) Well, I was absolutely anal about that valve clearance, and I probably actually had it just a little on the tight side. But it never made any noise !!! ( I dont run my 305 with loose valve clearance however !!)
Mike (older, but wont claim to be any wiser)

[maia]

JL Youv'e probably already checked this but...the rubber carb tubes from carb to cleaner, have you checked for leaks or cracked rubber? This caused me all kinds of grief till I figured it out . They wouldn't leak at low RPM but as I got to a certain speed they would start leaking and lean the mixture and my plugs were lilly white which caused me to adjust mixtures which caused more problems. Good luck

[Jlovvorn]

Thanks. Will get the flashlight and add this to the list.