400EX to 440

[Demoniac]

I was looking at rockymountain ATV's web site and saw a mod for the 400 that would give it a displacement for 440, can it be put together without professional assistance? or do I have to pay someone?

[K_Fulk]

Youll at least need to have someone install the sleeve.

[Demoniac]

does it take machinery or something? I know a guy who worked as a mechanic for awhile for cars, could he do it?

[K_Fulk]

Ask him, I dont know the guy.;) Typically you would need a machine shop to do it.

[Demoniac]

how much would it cost to pay someone to do it?

[K_Fulk]

Originally posted by Demoniac
how much would it cost to pay someone to do it?

Around 100 is an average price.

[Demoniac]

ouch

[K_Fulk]

I checked ct racing website and there price was 125. Find a place that rebuilds engines and ask them. Everyone charges a diffrent price it seems.

[Demoniac]

I'll probably just do what I was orignially gonna do with my 400, cut the fenders, rejet the carb., and put neon lights under it, so I can beat my friend's quad, he bought it used and it's race ready

[440ex2001]

you'll need to do more than re-jet your carb to beat him. If its all stock you dont even need to re-jet. Why don't you just get a 11:1 piston or a slip on pipe. Those would help alot. U could do the 11:1 piston pipe and a hotcam and have a pretty fast quad. If you keep the same size piston there would be no need to have it bored out and you could get your mechanic buddy to do all the work its really easy.

[Demoniac]

and how much money am I looking at if I do it that way?

[K_Fulk]

For a hotcam, and a higher compression piston your gonna be looking at around $200 plus getting your cylinder bored or honed depending on what size piston you go with.
It wont be fast but it will be a lot better than it was.

If your wanting a fast 400 your gonna have to lay down quite a bit of green.

[TC426EX]

Originally posted by K_Fulk
If your wanting a fast 400 your gonna have to lay down quite a bit of green.

Exactly... It takes around 2 grand to get a 400ex as fast as it can go. The reson youd have to pay someone over 100 bucks to get your cylinder resleeved is that it is a process... You have to heat the cylinder up to extremely high temperatures an press the sleeve in. If you dont want to do that but still wanted to bore your bike out you could install a 416 or 426cc piston kit on the stock sleeve. All you would need to do in that case is get the stock sleeve bored out to either 416 or 426 and you save the money of resleeving.

If you really want to wake up your motor significantly I would reccomend doing one of the piston kits I mentioned above, add a cam, a K+N filter w/0 the airbox lid, and a full exhaust....

[Engine Tech]

Just put a 426 piston kit in. You could do that yourself all you would have to pay is about $50 to have your stock cylinder bored. A 440 kit is typically only about a 432 the performance will be the same but the over all price is a lot cheaper because you are not paying for a new sleeve and the machine work to have it installed and preped. Check out our site and feel free to give us a call if you have any questions. www.enginetechatv.com/

[markk]

I would have somone built u a 440 with aftermarket parts that work better. But i really would build up somthing besides a 440, 440's have alot of head gasket probs, U usally need to buy oversized studs and all sorts of things!

[440ex2001]

Originally posted by K_Fulk
For a hotcam, and a higher compression piston your gonna be looking at around $200 plus getting your cylinder bored or honed.


if you just get astock bore 11:1 piston you won't need to bore your sleeve. You an hone one yourself.

[Demoniac]

what's "honed" mean? I'm just getting into souping up quads so I'm not sure what everything means and how much are these pistons 440ex2001 and Engine Tech talking about?

[K_Fulk]

Honing just rough up the sleeve somewhat so the rings will seat.

[markk]

Now what actully seems to work better, Honeing stones, Or a ball hone??? Or is there really any diffrence between the 2? I know that mine was done with a ball hone! And the rings seemed to seat up pretty well!

[TC426EX]

Either one will work just fine... You can either pay a shop like 15 or 20 bucks to hone your cylinder for you, or you could just purchase one for the same price and have it for the next time you rebuild your topend/rings. Buying one is definitely worth the investment if you plan on doing work and maintenance on your own engine down the line. Every time you take the cylinder off or the motor apart you have to re hone the cylinder and get new rings...