400ex was a 426ex sputter and spits

[dirtdog400ex]

Ive got a 400ex that the engine just got finished being rebuilt back to stock. It was a 426ex before it locked up and I used 110 octane gas before it was rebuilt back to stock. It still has a hotcam ported and polished and a few other mods. But since I got it rebuilt when I start it, it'll idel just fine but when I get on it it'll bog down then smooth out then bog again. Im not sure if i need to raise or lower the needle in the carb or could it be something else? Someone please let me know ASAP im suppose to go riding tomorrow. Any info would help.

Thanks

[cals400ex]

so, now your running a stock piston? what else do you have done to the bike? pipe? air box lid on or off?

[dirtdog400ex]

Yea a curtis sparks pipe and no airbox just a k&n filter with an outterwares cover

[cals400ex]

i would try a keihin 158 mainjet, needle clip in 4th position, and a 40-42 pilot jet. by the way, these are all keihin jets, not dynojets.