best 440 work and who?

[reichart90]

ok so heres the deal. i bought my 400ex with the 416 kit already done to it. the quad has nearly everything aftermarket imagineable done to it. i'd love to have even more power so im thinking about the 440. i know this is something i cannot do myself (lack of tools and experience). who is a good person to send the engine away too to do it RIGHT for the best price and performance... also anyone have any idea how much something like that would cost me and if its even worth it? i dont race... jsut ride the mx track for fun and some trail riding. i have no intention on getting rid of the quad for quite sometime.

[reichart90]

oh yeah, also i am almost positive its the stock carb on it. would a different carb give me a little boost. my buddies all have kfx400s and smoke me. lol that bothers me. i have a 14 tooth front sprocket. (no i dont want NOS either haha)

help me make this sucker faster.

[rneal]

My personal experience is that the razr 2's really slow down a 400ex. The lighter the tire the easier it is to turn. The other problem could be your 14 tooth sprocket. They are great for hill climbing and the tight and twistie trails, but it kills your top end. Your 416 should have no problem pulling stock gearing (15/38). I'd try some different gearing combo's before going to the 440.

If you still want the 440 installed, I'd turn to GT Thunder (http://www.gtthunder.com/) .

[reichart90]

so i was flipping through DirtWheels in the back there where the classifieds are and found this place: http://www.advmachining.com/

does these seem like good prices?

i wouldnt hafta pay shipping either cuz its like 20 minutes away from my house lol

also what would be better for power... the big bore kit or the stage2 porting. im slightly confused here. haha sorry im still learning a lot being that im fairly new to the sport

[nakomis0]

Could do it yourself. And just find someone to do the machine work.

Keep the 416, go with a Ross piston 11:1 compression, a larger cam, porting, and some valve work.

Probably cost you about a grand, but should get you close to an additional 10hp

[prepracing]

would be cheaper to try the 426 first, they give pretty equal if not more power than most 440's. But if your dead set on the 440, call GT thunder, fourstroke tech, or C & D racing here on this site.

[400exrider707]

Originally posted by nakomis0
Could do it yourself. And just find someone to do the machine work.

Keep the 416, go with a Ross piston 11:1 compression, a larger cam, porting, and some valve work.

Probably cost you about a grand, but should get you close to an additional 10hp


My guess is that he is already at 11:1 if not more with the 416 kit, so a ross piston isn't going to give it any more power really. I say if you want a 440 go for it. Just remember that compression is going to give you more power than boring. A larger carb will only help if you get porting and oversized valves, which would be a good choice to do as well like nakomis0 said. Also all of the builders mentioned so far are good choices.

I also agree that you should lose the 14 front sprocket. I ran stock gearing (15/38) on my stock bore 11:1 with a stage 1 cam and it was just about perfect. That should help with the kfx problem.

Also from that really horrible quality picture it looks like your rims might be flipped, turn them back around for crying out loud!

I riecently put a fcr carb on my 416ex that is pretty much modded to the max in the engine department. well not really. but it is ported and high comp, timing advance, thin gaskets, valves. so it does alright, but with that fcr carb it woke it up pretty good.

[Mike_Rides_Red]

Going from a 416 to a 440 (really 435 cc's for 89mm) is not going to give large horsepower gains. I don't think it is worth redoing your piston for 19 more cc's. Go use your money on a high performance cam.