Well after doing some reading, I've learned two things about the 440 kit and hot cams. That the 440 kit blows head gaskets and hot cams are trouble. Before I do anything what has been your experience with a 440ex? Has it been reliable? This is the specific's on the one I'm looking at

11:1 Wiseco Piston(With Rings, Clips, Wrist Pin etc..)
Namura Big Bore Sleeve
Namura Top End Gasket Kit
Stage 2 Hot Cam.

Any idea's? They also have this kit in 12:1 and 12.5:1. I don't really want to use race fuel. what compression would you reccomend?

 

from what i hear u have to use different head studs with440 and i know 5 guys with hotcams in thier 400 ex but they used the hotcam from xr 400

 

Another issue with 400EX hop ups is running hot. The more power output the hotter they usually run and this has been a big deal with radical 400EX motors. So I think you need to take a good look at what your priorities really are. If you must run with newer liquid cooled 450s then you may be better off to sell the 400 while it is still a valuable and highly desireable used machine and just buy a newer 450. If you could be happy with just slightly more umph then maybe a less radical motor like a higher reving 416 might be better choice. Also with too much power then the suspension often becomes the next problem and you wind up with a bottomless money pit.

 

You recommend a 416 kit? That wouldn't compromise reliability? Its not going to make it run too hot? or blow the head gasket?

 

go with a 10.8:1 416, hotcam stage 2 or 3, sparks full exhaust, and jet it accordingly. you will have very very solid gains. you may even need a rev box if you are hitting the rev limiter. you probably won't with just a slip on but a full sparks pipe will help you out a lot if you want to go faster.

 

I picked up a well used 400 ex with a 440 kit this spring, it had been run hard by the former owner, and my son and I have rode this a lot to check it out, my son even raced it once on an MX track, so far,it has been great, lots of power, starts and runs like a clock, I believe the cam is still stock, with a White Bros E series pipe/silencer, and a White Bros cdi for a little more rev on top. The pull from the bottom is very impressive, but then we were driving a 300ex and a Wolverine !! It is very strong in every gear, revs and pulls hard to the top of each gear, I have not gotten a top end speed reading, but it is a LOT faster than my Wolverine,and that will go 57 top end. By 5th gear, the 300ex was over a quarter mile back !!

 

the thing is a stock 400ex should smoke a warrior, 300ex, and a wolverine. out of the builds we have built, the 440's were slower when dragging.

 

I have a 2002 400ex that I put a stage 2 440 kit on with 11 to 1 compresion with an edelbrock eichner carb and full lrd exhaust and it runs strong the main set back for me is jetting because of how many different combinations there are for pipes and etc. for them so I went with the edelbrock eichner and that made it all easy and yea I I am running the stock head studs with out a problem I was told that if I go over 11to1 compressin thats when they start breaking the studs off If you do check how you ride and where you ride because I ride in gravel pits and woods and the stage 2 cam is great for open areas and gravelpits where you want it to rev and it sucks in woods riding cuz your never in the power band at that low of speeds