what carbs do i need for a 4mil cub motor?

[2stroke in my blood]

hi guys. just bought a 4mil cub 421cc motor built by redline racing, 4mil with long rod, it has custom cut domes and was used on race gas but im thinking of changing it back to around 20-21cc domes as i only will be really trail/ some drag riding against mates. i know this motors not ideal for trail but i love HP!!! lol . what carbs ans size would you recommend, and why? any help will be appreciated, thanks heath.

also i will be running t'5 pipes!

[gotta_goatsfast]

General consensus is that 35mm PWKs work best for all around 421 cubs while something larger like a 39 is used for guys looking to squeeze a little more. In your case, however, I would consider 33mm carbs to match the pipe you plan on running. It kind of sucks you chose the cub for the riding you do when there are a lot of new configurations out there by CP industries that would have suited your riding style better. But, I've heard you can dumb a cub down a little and make it slightly less terrible in the trails haha. Anyway, 33 or 35 Keihins would work best for you (there's a TON of support from other members with these carbs and 421 cubs)

[dirtydownunder]

hey man, i reckon 35's would be sweet on it, my reasoning, just because haha.

 

id speak to redline racing, they are a sponsor on BHQ and know whats best for that motor.

 

but with those T5's on that engine, you could run stock carbs. you next big gain for that cub is a set of better flowing pipes.

[2stroke in my blood]

hey man, i reckon 35's would be sweet on it, my reasoning, just because haha.

 

id speak to redline racing, they are a sponsor on BHQ and know whats best for that motor.

 

but with those T5's on that engine, you could run stock carbs. you next big gain for that cub is a set of better flowing pipes.

thanks guys. yeah i was thinking around the 33-35mm mark. also, how much will the T5' pipes restrict my peak HP output? im obviously better off having some CPI's yeah??