Please help with 400ex jetting

[cowentz]

Lets start with what I have: 01 400ex, 11:1 weisco std bore, stage 1 hot cam, aftermarket rev box, uni filter w/ lid on, and DG full exhaust.

I just rebuilt the motor this winter with the piston, cam, and put the rev box on. I checked the jetting today to find out it is a 38 pilot jet, and the main has 146 stampped on it. The service manual says stock is a 148. I am not sure why the guy went down a jet size when putting a pipe and filter on. The main jet is round is this a stock kehin jet or is it maybe a dynojet??

Where should I start with the jetting? I am at around 500f - 1000 f elevation with normal riding at 70 - 90 deg. I was thinking a 160 main and a 40 pilot. Also will I need to move the needle? Thanks for any help

[Sparky_20]

if its round its a DJ. How does your plug look? does it run ok through the powerband?

[CarGuy7a]

yup 160 main with a 40 is where i'm at except i don't have the high comp. piston. try the 160 and if it's lean go to a 165. i have my needle set at one notch below what ever the closest one to center is.

[cowentz]

It is a round jet and kehin doesn't make a 146. According the the jet crossover chart a 146 dj is equal to a 160 kehin. I will put a 40 pilot in it and get a good plug reading to see where I'm at. After rebuilding it seemed to run fine the first 5 times I rode it. Then I took it upstate (higher elev). It ran ok for about an hour and then it started breaking up and bearly ran at all. I took the lid off and the filter then it seemed to run better. I replaced the filter now (old one was a k&N but really dirty and clogged.

[cowentz]

do dynojets have a dj in front of the number stammped on them or just the number? Thanks