Main jet Size for 421, with keihn D slide carbs ?

[kevincurtis]

Hey there was wondering if i could get a few opinions or suggestions on what size of main jets i should use with my 421 at sea level, to give me a better idea of where to start and save the troubleshooting. I have Keihn D- Slide Carbs, i think my main jet size right now with the stock .040 bore is 130's, i thought when re-jetting bore size didnt come into play, but i was told when im going with the big bore (404 Vitos) it did, any info would be appeciated. If You need to know what other mods i have done, just give a post thanks - Kevin

[252wheelieking]

Hey there was wondering if i could get a few opinions or suggestions on what size of main jets i should use with my 421 at sea level, to give me a better idea of where to start and save the troubleshooting. I have Keihn D- Slide Carbs, i think my main jet size right now with the stock .040 bore is 130's, i thought when re-jetting bore size didnt come into play, but i was told when im going with the big bore (404 Vitos) it did, any info would be appeciated. If You need to know what other mods i have done, just give a post thanks - Kevin

 

from what you have told us i would start out with a 162 mains. I have a 160 mains in my 421cub at sea level & it's still a little on the rich side.

[vulvafan537240]

421 cub? serval? 4mill big bore stock cylinder? what are the other mods (pipes, reeds etc)?

[kevincurtis]

421 cub? serval? 4mill big bore stock cylinder? what are the other mods (pipes, reeds etc)?

 

i have stock cylinders with the vitos 404 big bore sleeve, with the long rod 4mill crank, Im running V-force Delta 2 reeds, with the pro design manifold system and boost bottle, and Fmf fatty exhaust

[Oregon dunner]

I have have a 421 cub and my current setup at sea level is +5.5 timing, VF3, 19cc domes, 35 pwk carbs. Aggressive dune port by HJR 48 pilot,152 main, needle 4th from the top and 1.5 turns on air screw. It was dyno tuned at Redline Racing in Oregon