Motor work?!

[Blastermax]

Hey guys I just bought my 400 from my brother and so far im lovin it but im looking into gettimg some more power ( I already have a Curtis Sparks full system and Uni Filter) and I was thinking of sending my motor out this winter for a full mx build (426,440...etc) and ive been looking around and im kind of overwhelmed by all the companies that do things for the 400ex (I used to have a blaster thats why) so first off what size motor would you reccomment for motocross? 416? 426? 440? I have heard that the 416 lacks power somewhat and that the 440 overheats? Is this true? And what other engine mods will help out to compliment a larger bore? Carb, cam, porting and head work of some sort?? Any info will help me thanks!

Max.

Id get a 416 n maybe cam.. most reliable

[Blastermax]

Is that or are there other things I can get?

[400ex28]

416 piston, cam, port and polish, crf450 timing chain, hd head studs theres alot of stuff you can do.

[lil_billy_300ex]

honestly if i were u, i wouldnt do much, in my opinion i feel that the more u bore the slower it will rev. sure they may be fast and have power but when your racing u want the power right there, if a bore is a must 416 is the furthest i would go, but i also heard a good high compression piston, a cam, carb, cdi and suspension on a stock bore 400ex will be just as fast as the other 400s out there.

[Blastermax]

Yeah man i see what you mean thanks for the help!
Any other suggestions/help??

[tater_kamik]

i say a good bore/stroke combo for power. why? well, that is how you make power. an balanced motor is important, but i know that me built my friends 400 into an 440 and he loved it. i truly do not beleive that an 416 can compete powerwise with the other high performance quads when it comes to mx. look into the available mods (tons of them are available for your 400) decide what is the best for you!!! let me know if you have any questions!!!

[tater_kamik]

wow, i said "me" built, i meant we built!! sorry!:D

[Blastermax]

Well I have decided to get a 426 motor with a FCR carb but I dont know what other mods you can do to the internals of the motor? Im used to 2 strokes where you got port, polish, head deck, and all the basics, is there more you can get for the 400ex?

[tater_kamik]

you can do all of the same stuff, but instead of changing the timing with the porting on a 2 stroke, it is done by a cam. but when you port the 400 you still do change where you see the power gain the same as you would on any 4stroke.

[Blastermax]

Thanks alot for the help man!

[tater_kamik]

what little help i am i try, it seems like you are solid on your decision though!!! cant wait to see the end project, what else are you going to do during the down time?

[Blastermax]

Well this will be done in the fall/winter and done by the summer hopefully I still need a swinger an elka rear shock im thinking of getting the swinger from Houser or AtvFourPlay I posted pictures of my 400ex in the section for it but photobucket is down for a little it should be up soon though