For now here are my plans. I have a LRD pipe. I'm going to get the k&n power kit and jet my carb and all. Either remove the air box or mod the lid. Put CDI hi rev box and a advances timing key. I also plan on experiencing with a 14 tooth and a 16 tooth front sprocket. I race TT and need some power coming out of corners but i also do alot of riding at top speed and want alot of it. What do you all think?

 

Keys shear easily. XR250 cdi box will advance timing 6 degrees and allow 1200 more rpm. White Bros cdi box is made by Honda..check the part # under WB sticker with Honda. Honda XR250 cdi $84 or so..WB cdi $125 +shipping.

I'm assuming You're talking about a 400EX.

'99 400EX R-Series, K&N, 152, XR250 cdi, Gunner tether.
'97 400 Sport +.02 Weisco, 13 oz. lightened flywheel, ported, V-Force, DG pipe for now, K&N, Sur-traks on .190 alum....and can't beat the 400EX.

 

That key advances it 6 degrees also. But don't advancing help bottom end not top? right?

 

put a xr400r cam in it to and then maybe a carb