Jetting assistance

[Handyman]

Ok this is more of a re-assurance question..... I think I have it right....I am getting my banshee's ready for a Pismo trip in June...On my 421 cheetah Powervalve motor I removed the 150 main( for 4500ft elev.) and installed a 142 main with a 45 pilot, air screws 2 turns out. Is this going to be sufficient for Pismo (sea level)?? I have main jets from 142 up to 170. I have one extra set of pilots that are 48's....Any assistance will be greatly appreciated....

[rubberneck]

Ok this is more of a re-assurance question..... I think I have it right....I am getting my banshee's ready for a Pismo trip in June...On my 421 cheetah Powervalve motor I removed the 150 main( for 4500ft elev.) and installed a 142 main with a 45 pilot, air screws 2 turns out. Is this going to be sufficient for Pismo (sea level)?? I have main jets from 142 up to 170. I have one extra set of pilots that are 48's....Any assistance will be greatly appreciated....

 

Nope, you went backwards. if it was jetted correctly with 150 mains at 4500 feet, you will need to go up on the mains at least 2 sizes. personally i would start with 3. I would put a 160 in there and see how it acts. might want to go to a 48 or 50 pilot also, but start with the mains and see how it runs

 

[AKheathen]

well, actually, that depends on the fuel. if you run local pump 93, then you'll probably end up down 2 sizes. if you run sunco, or other higher octane fuels, than the fuel will be formulated the same no matter where you get it, so then you go up a couple of sizes, actually between 2-3 sizes, like stated

Edited May 24, 2009 by AKheathen

[Handyman]

yeah i figured that out... a couple people over on DC helped me out.. .When I was explained how jetting worked the dude that explained it to me explained it backwards....basically said the higher you go the bigger the main etc....I will run a 170 main with a 48 pilot and start from there...