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Posted

I just never heard of a 421 cub running such small mains. But yes every motor is different my old 350 the lowest it would take were 158 mains..

Posted

Wow you guys are all running a lot bigger mains than I am. I have a 421 cub clean up port with shearer inframes and 34pj carbs and I am running a 50 pilot and a 148 main and have been runnning that setup for 2 years. Make sure you are turning your choke knobs all the way in and adjust the idle with your cables other wise you are going to have a hard time getting those pj's set right.

  • 2 weeks later...
Posted

Sealevel. 421 cub. HJR full port. CPI inframe. Trinity billet intakes. +5 timing. 35pwk. 48p, 152m, CEL top clip. 2.0 air/fuel.

 

Anything richer and the motor hates it.

Posted

ok got the bike together and did a leak test, lost 1psi in 6min. is that acceptable? anyhow, now my left side pipe is getting hot way b4 the right side. carbs are synced pullin 4 even on the syncronizer. i got spark on both sides, what else kud it be fellas??

Posted

Sealevel. 421 cub. HJR full port. CPI inframe. Trinity billet intakes. +5 timing. 35pwk. 48p, 152m, CEL top clip. 2.0 air/fuel.

 

Anything richer and the motor hates it.

 

I almost have the Identical set up as you. Have you used a bigger pilot then a 48?

Posted

Finally g the bike out riding today and she's running good. A 165main jet is still very rich, so il b dropping down to a 162 or 160 main. Maybe mess with the needle a bit and see what happens during the week. Il post up vids next week with the go pro cam. Shud have some good footage

Posted

im jetting my 421 cub now, 165 mains wont let the gears rev out so im droppin them now.

 

set up: 421 drag ported, shearer inframes, 35mm carbs, +3 timing on pump gas, 4mil hot rods

Posted

Fired mine up this weekend and so far seems a bit rich.

 

Set up:

421 cub stock

22cc domes from FAST

HR crank

Timing +6

VF3

35mm pwks with CEL needles 162m 55p 1.5 out

Shearer SB in frames

Nology coil and wires

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