400 ex question

[REPOMAN]

i had a 440 and tanked the bottom end. bought a newer motor that is a stock 400. my carb needs to be rejetted. what jets do i need to use? thanks in advance.


i am also thinking of taking my old head with the kit in it and putting it on the new motor

[JimmyHoffa]

If you're running a stock block with a full aftermarket exhaust, start with a 165 main and 3.75 turns out on the pilot. That should be close, if you have a decent pipe that flows fairly well.