I was looking at a 440 bore kit for my 2003 400ex and a friend of mine told me that it would run to hot. Is that true? Is there anything i ca do to make it run not so hot? And what kind of a power gain would i get from the bore kit? and is it worth the money?

 

yes it is worth the money you will love the power gain.. About keeping it cool.. There are air scoops you can buy. I actually have some I've just been too lazy to put them on yet so I can't tell you how much of a difference they make

 

I have heard running higher octane fuel will run the engine cooler as well.

 

I run 110 octane and have never had a problem with overheating

 

Save yourself a big pain and do not use the bore in 440 kit. It will run hot. Just put in a 11/1 piston and a Hot Cam stage 2. Use your stock head pipe with a T4 or bills exhaust. Then if you need to you can go over size with a pistion. The 440 kit can not be bored. You have to put another 440 kit in again.

 

what do yo mean by the 440 kit can not be bored again?

 

When it is time for rebuild you can not bore the cylinder you have to resleeve it again. That and they over heat. That is why you see so many 440EX for sale.

 

..How does an air cooled motor over heat?Boils the air?..lol. come on..yea they might run hotter but so does everyother built motor.I ran a 440 for almost 2 years,not a single problem,look at how many ppl race 440's running 13.1 and your just going to run 11.1 dont worry about it. Dont waste money on air scoops,call Micky Dunlup at fourstrock tech.He makes a larger oil cooler for the ex helps keep the oil a lot cooler and saves a lot on the clutch.And puts cooler oil on the cam.He has a very good idea.
And i think you can over bore the 440,just depend on witch kit you get..there all called 440's but they have a 88.5mm piston witch is like a 435cc and an even 89mm witch i think is a true 440? Get the kit with a 88.5 piston then you can always clean bore it later on.I think??..

 

I love driving my friend's 400ex. It has tremendous power. How does it feel when you go from a 400ex with the 397cc displacement to a 440 kit? Do you feel that it's best to put in a larger front sprocket?

 

I have a 2001 440ex and it is very dependable and has no problems overheating and is always a top contender at glamis every trip!!!! If built properly and mantained i feel the 440 ex is the king of the hill !!! just buy quality parts and you won't be sorry !!!![img]i/expressions/face-icon-small-wink.gif[/img]