400ex high compression piston and hc cam

[gcart2]

i have a 2004 400ex and have been told i need a high cop piston. i looked on www.magicracing.com and found a wiseco piston with stock bore with compression of 11:1. is this better than stock? and is this a high comp piston? also i am on a limited budget but need a faster fourwheeler... what can i do?

2004 400ex
dyno jet kit
k&n airfilter
fmf power core four exhaust
pr armour bumper and pegs
lsr extended a-arms
lsr extended axle


PS:i am going to race motox and need part advice for motox

[gubertrious]

i just put a a 11 to 1 piston and stage hot cam in my 400ex an it made a world of difference lots more power i would defiantly say it is worth it

[ride_red666]

yes its high compression. the lowest you can run is 91 octane pump gas with 11:1. youll notice a bit of a difference but i would bore it to like a 416 cause then you can bore out the stock sleeve and wont have to resleeve which gets more expensive.

[whiteEX]

yeah i have the 11:1 piston in my 400ex, it hauled, then i put that stage 3 hotcam in it and it really woke my engine up, if ur just starting out racing, thats all u really need

[lilhouskey]

i thought stage 3 was for a big bore?

[XXXRACER165]

Originally posted by lilhouskey
i thought stage 3 was for a big bore?

It is for big bores. I have a stage 2 (which is the new stage 3), in my 440 motor. It has longer duration grind to let bigger engines breath better:devil:

[eliasxr400]

I put a stage 1 hotcam and an 11.1 std. piston in my 400ex a few months ago. This thing pulls hard all the way thru 5th gear. It hits the rev limiter in all gears when it wouldn't before. I also use a slip on pipe, K&N with no lid, Rejet, and 13th front sprocket witch helps a little. I can pull away from stock lt400s.
These mods are well worth the coin. The piston, cam, and gasket are under $300(check Ebay), and can be done yourself with a tear down book. Just make sure to get good gaskets and torq to specs. Also hone the cylinder. I think you can rent hones from Advance auto of a place like that.

[whiteEX]

yeah it does work with the big bore, the stage 3, yeah but they consider any changing in pistons, thats what wiseco considered there bore. so i just went a head and got the stage 3 and my bike now hauls ***, i can beat ltr450s and yfz's no joke

[lilhouskey]

i see, good to know. i have an 11:1 Std bore waiting to go in but i was gonna do a stage 1 cam, so you would reccomend the stage 3? i was gonna do the piston myself but im worried about putting it back together with everything in the right position and i have heard that shimming the cam is a pain in the ***.

[GPracer2500]

The 400EX doesn't use valve shims. It has screw tappets--easy.

[whiteEX]

yeah in some ways it is pretty easy, just make shure u use ur manual, yeah there isn't much off a difference in the price between stage 1 and 3. so i just got the three, even a couple mechanics said that would be the best idea, and now my bike hauls. like i said earlier, i can beat ltrs and yfz in the dunes on the drag strip

[lilhouskey]

alright sweet well if it gave you good gains i might have to go that route too, and if it is that easy to do i might have to give it a shot myself. with honing the cylendar is it easy to mess up your sleeve or is it pretty basic to do? cuz thats the real big thing holding me back from doing it myself, i dont have access to one so ill probly just buy one and ive never had to hone a cylendar before so i dont really know how to do it.

[whiteEX]

if u really are worried about messing it up, just take it to a local shop, that would be good, cause ur gonna regret down the road if something goes wrong with ur engine

[GPracer2500]

I'd recommend taking your cylinder and new piston w/rings to a machine shop. Have them hone it, check/set the piston-to-cylinder clearance, and check/set the ring end gap. It won't cost much and any machine shop can do that kind of simple work. When you get the cylinder back it will be ready to go.

Assembly and dissassembly is work you can do yourself. Leave machining work to a pro unless you have the right equipment and are sure you know what you're doing.

[bigmikey119]

The shop down the road from me charged me 8 bucks to hone it 60 to bore!

[lilhouskey]

lol nice alright i think thats what im gonna do, i live in an oil town so theres no lack of machine shops here ha ha