Oregon dunner Posted July 27, 2012 Report Share Posted July 27, 2012 In my opinion every motor is a little differnt. Quote Link to comment Share on other sites More sharing options...
hp2000 Posted July 27, 2012 Report Share Posted July 27, 2012 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.. Quote Link to comment Share on other sites More sharing options...
Oregon dunner Posted July 27, 2012 Report Share Posted July 27, 2012 I know of a few other guys that use a 152 to 155 on there ported cubs. It seemed to like leaner jetting once I got the cylinders ported. Quote Link to comment Share on other sites More sharing options...
BUILDER Posted July 27, 2012 Report Share Posted July 27, 2012 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. Quote Link to comment Share on other sites More sharing options...
bansheeboie Posted July 27, 2012 Author Report Share Posted July 27, 2012 ok thanks for the info rubberneck, didnt kno that about the pj's. thats prob exzactly what i need to do. Quote Link to comment Share on other sites More sharing options...
hp2000 Posted August 5, 2012 Report Share Posted August 5, 2012 Anyone else ? Post your set ups only.421 cubs gas... Quote Link to comment Share on other sites More sharing options...
sprinklerman Posted August 5, 2012 Report Share Posted August 5, 2012 421 gas, shearer inframes,V3's,UPP intakes. 39pwk ,152mains,55 pilots,DGH needle 2nd richest. Quote Link to comment Share on other sites More sharing options...
werner Posted August 5, 2012 Report Share Posted August 5, 2012 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. Quote Link to comment Share on other sites More sharing options...
bansheeboie Posted August 7, 2012 Author Report Share Posted August 7, 2012 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?? Quote Link to comment Share on other sites More sharing options...
werner Posted August 7, 2012 Report Share Posted August 7, 2012 Small airleak sucking air in that cyl or carbs not synced properly Quote Link to comment Share on other sites More sharing options...
Oregon dunner Posted August 13, 2012 Report Share Posted August 13, 2012 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? Quote Link to comment Share on other sites More sharing options...
bansheeboie Posted August 13, 2012 Author Report Share Posted August 13, 2012 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 Quote Link to comment Share on other sites More sharing options...
vulvafan537240 Posted August 13, 2012 Report Share Posted August 13, 2012 (edited) Sounds good. Keep us informed. Edited August 13, 2012 by volfan537240 Quote Link to comment Share on other sites More sharing options...
mike0chek Posted August 14, 2012 Report Share Posted August 14, 2012 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 Quote Link to comment Share on other sites More sharing options...
hp2000 Posted August 14, 2012 Report Share Posted August 14, 2012 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 Quote Link to comment Share on other sites More sharing options...
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