88mm 426 piston questions..

[AtvKid4Eva]

hey guys im gonna be putting a 88mm wiseco 426 piston into my brothers 01 400ex and have a couple questions.

1.) for the gasket kit i see cometic only makes an 87mm and 89mm top end kit..do i use the 89mm?

2.) i know a couple people running stock cylinders bored for a 426 will it be alright or is it necessary to resleeve?

3.) at 11:1 compression is it necessary to get the HD head studs, as i know a couple people using the stock ones without problems.

this is the first time the motor has ever been opened up. ive built several 400ex motors most were 416's tho.

thanks guys. -Bobby

[CJM]

1. You can use the stock size gasket, it actually doesnt seem to matter is the general consensus.

2. Just bore it, will be fine.

3. 11:1 shouldnt require studs, I did them on my 416 build for extra insurance but its not necessary.

Get a CRF450 timing chain and replace the guides and auto tensioner to be on the safe side if I was you.

[AtvKid4Eva]

wouldnt a gasket set with a hole smaller than 88mm cause problems? or would it still have some clearance when the piston moves within the cylinder? why do they make different size gaskets then?

[CJM]

Originally posted by AtvKid4Eva
wouldnt a gasket set with a hole smaller than 88mm cause problems? or would it still have some clearance when the piston moves within the cylinder? why do they make different size gaskets then?

That I cant truly answer, but many have no issues with stock side gaskets. I think there might be enough wiggle room or something.

[m36indiana]

if you go 87 mm id use the 89mm gasket stock will not work

[CJM]

Originally posted by m36indiana
if you go 87 mm id use the 89mm gasket stock will not work

And see I was reading the opposite, but I could be wrong. Maybe it works up to 87mm..

[honda400ex2003]

myself along with a bunch of others have been running stock 85mm gaskets for a long time with 87mm. no problems here, the piston doesnt come up that high anyway. for 88 you might as well get the 89mm or get ahold of gt thunder or c and d they will have 88mm gasket kits for you from cometic. they stock them most of the time. steve

[killer400ex]

if you buy the piston kit from wiseco they send you a top end gasket kit, including valve guides and valve cover gasket. and it is the correct size for the piston even thogh it honestly dosnt really matter. the 426 piston is the highest you can go safely without re-sleeving, it will be just as reliable as stock imo. if your adding compression like i did with an 11:1 your going to want to put a bigger cam in to help the bigger bore breathe better, and no you dont need hd studs with this build because i did a 426 11:1 with a stage 2 cam, port and polish, full exhaust and i raced it just like that for about 3 years with absolutely no problems, just basic maintenance like regular oil and air filter changes will keep it healthy, ohh and dont run below 93 octane with the higher comp, learned that one the hard way