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need help jetting 421 stroker


bansheeboie

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hey fellas im in process of doing a 4mil 421 stroker dune/play port on my bike. i have a pro design head and wil b running 21 or 20cc domes, on pump gas. im at sea level and the temp is between 30 and 45 degrees. i have 35mm keihin carbs and will b using small bore cpi inframes.

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You should be right around a 155 to 160 main jet and a 52 to a 55 pilot

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You should be right around a 155 to 160 main jet and a 52 to a 55 pilot

 

421 ported cub. 35 pwk. Vf2. Cpi inframes.

I just finished my tuning today and I ended with 48 pilot and 155 mains. Still slightly rich. Currently running dek needle (rich) on top clip but i will move to cel (leaner). Redline will be dyno tuning soon so we will see How close I came.

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