I have a 2000 400ex. It has K&N Air filter, and white brothers E series exhaust. I just had the top end rebuilt and it has a wiseco piston. I checkd the jetting and it has a 165 jet in it. My only concern is whether this jet is letting the engine run too rich and some unburnt fuel will come out as blue exhaust. Im new to these things and from what I am hearing, is if you jet too small, you get heat buildup, and if you jet too large, you get unburnt fuel and engine choking. I think that the stock jet for that motor is a 148 or a 150. Any comments appreciated.

Thanks
Nick

 

stock is a 148 main.......

165 sounds pretty good for the mods you have