400ex big bore suggestions

[gdebrule]

Got a quick question for you guys who know about big bores and cams. I recently purchased a 2004 400ex with a blown engine. The engine was not worth rebuilding so I got one on ebay. Turns out that the crank is bad, knocks real bad at low rmp. I'm not to upset because I get parts at close to cost and rebuild atv engines myself. I have never done a big bore kit and sense I have to tear the engine completely down I figured it's about time to do one.

My question is simple. What all do I need to buy to turn this thing into a 440 or mabe a 460. Any suggestions on kits? Also, will i need to jet the carb with the added cc's?

[(815) REDDEVIL]

to go 440 all you need is the big bore kit and sleeve which will require borin out your cylinder.

to go 460 you will need the same and possibly modding your piston for clearance and even center case maching in some cases.

i want to use a 92.5 mm piston but i dont wanna have to rip my engine apart and rebuild just to have center case modded due to having pc4000 power cylinder.

cant i just bore out to use the 92mm piston without modding

[(815) REDDEVIL]

as for jetting im certain youd have to change but its never possible to know until youve got the 440cc on there.

[Wheelie]

If you're splitting the cases, take advantage of the situation and stroke it. Buy either a Hotrods 460 kit, or I highly recommend www.powroll.com.

BTW--If you go with Powroll, have the HD rod installed. Cheap insurance.

[gdebrule]

I really didn't want to spend that much money on the engine. I guess I underestimated the cost of the kits. Does anyone know of someone with a kit are possibly just a stroker crank?

[Wheelie]

Unfortunately I don't. If you find one, remember to have the piston modified to fit the crankshaft. Some strokers use a shorter rod with a short skirt piston. Some strokers use the stock length rod with the wrist pin location moved up in the piston.

[gdebrule]

How much was the total cost for you to turn your 400ex into a 440?

[Wheelie]

For all the gaskets, seals, P&P the head, cam, cam chain, crank, rod and piston. About 14-1500. I did all the assembly and teardown myself.

[gdebrule]

Did you have to replace the cam chain with a high performance. Also, did any work need to be done to the cases or head to accomodate for the stroker crank?

[Wheelie]

I installed a 450r cam chain. No machining work required on either the cases or the head. Anything over a +4mm stroker, machining work is required.