421 cub

[evoorng]

i was wondering if anyone has a 421 cub with 38 muk carb. i was wondering what jetting people are useing. i got my motor in my bike and the builder put a 350 main jet. im shocked that it is that big. any help would be great. oh i am using race fuel.. thanks

[wesw]

if you dont get any answers on here, you might try dave moore racing, he is a big mikuni guy. he shoudl be able to get you going.

[Ducman]

I'm running a 421 cub setup using 68mm blaster pistons with Mikuni Flatslide TM 38mm carbs. I'm running 35 pilots, P-6 needle jet orafice, needle on the second clip from the top, and 340 mains. Also +10 timming, Rocket inframe drag pipes, & pod filters. Depending on your pipes and intake mods you might even go down to a p-4 (leaner) needle jet orafice. I ran a P-8 with my +4mm stock cylinder dune port motor and they were way to rich for the cubs. Depending on your other mods 350 mains may not be too rich. My motor will run good on mains are a size or 2 big but definitely doesn't like the needle to be too rich.