so what else do you sugest i get in addition to the big bore 440 kit so that my case wont crack? do u think i should just get a biger cam or crank shaft i have a stock 2002 400ex and i wont to be able to smoke a raptor. i can almost beat a stock raptor but he got me by one 4 wheeler lenght. i thought for a 660 the dang thing would leave me siting but there top heavy and have terible balance unlike the 400ex and the Honda reliability is wonderful compared to the raptor.

so what do i need besides the 440 kit to have a reliable 4 wheeler has any just got the 440 kit whould just this kit lead me to trouble like cracked cases and other stuff i dont wont. i ride prety hard and i wont to have a bullet prof atv like i have now but lots of power. if i got the 426 kit would i have to worry about cracked engine casing and other crap could i just put the kit in


and what would you guys recomend i do i wont power and reliabilty but i only have 500$ to spend on my engine

would the 426 kit be more reliable

or is it true if i just put a 440 kit on there that i would have know trouble if i kept my oil changed frequently please let me in on any info u might have on this thank u very much

 

sounds to me like on other post that if u do major engine mods like the 440 then the counter balance and the crank shaft will explode and crack the engine case

(I think i stick to jeting the carb, filter, and a good pipe)

i need power but i also wont my engine to hold together

 

Outlaw ATV in NJ doesnt not take the job to do a 440 unless you also get the crank done. They say the rods break so that must be the cause to some of the problems. I know of 440's done by them that are two years old now and they haul azz and have no problems. They use a different rod dont know what kind though and true and weld the crank. Their # is 732-786-0300

 

Anytime you modify the motor, you increase the chance of it blowing up. Obviously the chances aren't that great, as there are hundreds (thousands?) of 440 sized 400EX's running around with stock bottom ends.

The 2 possible reliability issues I see with a 440 vs 416 are:
1) The 440 piston weighs more, putting more stress on the engine.
2) It makes more power, therefore stressing it more.

I'm converting my 12.5:1 stock bore to a 440 11:1 in the very near future, and I'm using a custom machined Ross piston with a special alloy pin to keep the weight down. It'll end up being within a gram or so of the stock assembly. Can't do much about #2, kind of a good problem to have.

I'd say a 426 kit wouldn't be any more reliable, I actually think the cylinder walls are too thin with this combo. On the other hand, none of the kits from high compression stock bore to 440 really have shown to have serious reliability issues.

For $500, have you seen the "Gabe" exhaust mods? Here's my proposed recipe for economy mods: Remove airbox lid, uni filter, jetted, XR400 cam, XR400 head gasket, light cleanup work on the ports (even with sandpaper), clean out welds on the header pipe, "Gabe" mods to the muffler. Total cost here: about $200. If you're willing to run race fuel, there are some other easy ways to make power.