Re-jetting Question

[JayLee]

Just added some mods to my otherwise stock 2000 400ex. A Graydon full exhaust system and a Pro Design foam filter. Any suggestions about what jets to run or any adjustments. Also, would a timing advance key offer any improvements? I ride mostly at sea level but I'm always trying to jump higher!:D

[phebus]

Lid on or off? Lid on, I would say a 152 Keihin main. Lid off, I would go with a Keihin 155 main. Sea level, in nice and warm So. Cal. I would stay with your stock pilot if it starts fine, if not, a 40, and needle clip in the stock position. That should get you real close.

[JayLee]

Thanks for the quick reply!
Is there any noticeable gains from running without the airbox lid? I saw on the Curtis Sparks website that he offers an airbox screen to replace the lid. This seems like a good way to go unless there really isn't that much of a difference. I'm definitely not trying to be the "fast guy" but I do want as much performance without sacrificing reliability. Any remarks on the timing advance key?