Originally Posted by Firstman
I have been on a 450 mile road trip thinking about your issue. A constant rich/lean mix would show up on the plugs, but something killing the fuel would not. I worked on a carbureted bike that had a similar issue, at 65 mph the bike would stumble. I was able to reproduce the stumble reproduce the issue at certain RPMs, it turned out to be a piece of dirt that looked like a single flake of pepper that would lodge itself in the main jet only when X amount of fuel was being consumed.
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I really appreciate this. I'm coming to the conclusion that it's a fuel interruption problem too, either as you describe or (hopefully) in the petcock or that screen I understand is near the left carb. I'd really like to rule that out before getting into the carbs. I did take the top covers off the carbs and the - I guess those are what's called the diaphragms- the thin black rubber membranes through which the needles and springs go; were in fine shape.
I really want to get a good understanding of how the Keihins function and how to trouble shoot them, but I am not there yet, so I'm being cautious. Also because the bike really runs well in all other ways- starts fast, idles nicely, no backfiring, no stalling; so I don't want to screw that up. And I am
capable of screwing it up.