I never even saw you with a camera Tim, shows how observant I am. It's not very flattering being filmed learning the track...kinda like here's what not to do.
At least you didn't get footage of my off track prowess.
Paul, so far it likes #20 pilots, although that may change. It seems odd to me that if carburetion, it only shows at that 9k mark. (I did try a different Dyna box thinking it might be rev limiter, but without change.) However backing out of the throttle when it occurs cleans it up a bit so Mike suggested it's over rich at that point and dropping the needle helps. He has wisely suggested to try a richer needle dropped a clip or two. It suffers more the hotter it gets, which agreed is a sign of being over rich.
First I want to follow my nose. With these smoothbores there is an air jet in the inlet that directly feeds the needle jet. I get no response changing up on the mains above 115 and as a matter of fact even without a mainjet it only goes rich @8500, so the first test is with a smaller air jet which are cheap and available. My theory is too large an airjet may be disquising the needle jet as over lean??
It is a nightmare trying to sort through different needle option charts. These things are old and needle selection isn't what it used to be, seems if you find a needle that looks good, it will be longer than the one that needs replacing. If the air jets don't help, I might go with a richer needle jet instead and follow Mikes suggestion of running the needle lower to lean it out on top.
The carbs are back on but it's rainy & miserable, so testing can wait.
My improved chain roller tensioner lasted only two hundred clicks (should have listened to TG & Simon) Here's the replacment which mounts in the same location and will be allowed some chance to pivot.
