[kysoldier]

Hello guys. Im not new to off roading at all been rideing for over 20 yrs but not grat on repairing and specs but i have some ?? That im sure has been asked alot and im sorry but i do have more ??. I just got a 01 400ex thats been beat up and smokes like a train. Any work or money into it will not be stock of course. We i do ride my friends have there atvs built majorly and not trying to beat them but keep up on the trails and have a reliable atv. I have been doing some research and still cant seem to find the right anser. Firstof course 440 and 426. I have heard the 440 is as a bad idea with overheating and reliability but was told that was due to incorrect jetting. 426 i havent heard anything bad about it but maybe it would be better with a hotter cam jet and exaust? Also i heard that a 450r carb works great on the 400 but then i heard that the stock with proper jets is fine. Also if i do go with the 440 i know my stock head gets bored and sleeved but i have seen heads that are new with no sleeve wich would be a better bet if i was to go that way. Also oncne the motor is apart and modded is there anything else that should be done to help with reliability or just a little extra power? Of course with the build ill be getting a full exuast and new rev box. Any and all help would be great thanks

 

[blowfishRus6]

over heating..... put a bigger oil cooler on it. thats what i would do. i hear the 440's blow head gaskets if you dont get the stronger head bolts.

i would just have your stock jug bored out to the correct size.

thats about as much as i can help out.....