Looking for proper jetting for FCR...

My bike has a new 434 Big Bore, Hot Cams 3x3 full exhaust, and is at sea level. I'm using a used FCR 39 MX. Runs like a raped ape but can't get it to idle right. Motor races no matter what... No leaks... Nothing sticking... ??? I don't know what jets are currently in the carb. Looking for any info... Thanks!

I assume you already tried turning down the idle adjustment, if not then adjust it. You might still have a vacuum leak at the intake boot. And you need to find out what jets are in it and where your fuel mixture screw is set.

Thanks guys! This will give me a baseline.

Found the problem. There is a crack in a screw housing on the top. Looks like the previous owner forced a screw in there.... hoping a new o-ring and some j-b weld around the crack will do the trick. One of the hazards of buying used... was from a member too... oh well.

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