Blown top end on 416ex

[WhiteBros400ex]

Is it hard to rebuild the top end on a 400ex i had a base gasket leak and the top end blow up and i need to replace around how much does it cost and i know a good bit because i go to vo tech for small engine so i know how to rebuild things i just never took a 400ex apart motor wise. And would i need a new bottom end and new values for blowing the top end. Thanks for your help and im looking to put a 426 with a je high compression it had a wiseco 11:1 what ratio should i get and how many over to i bore for a 426 .080 thanks guys. Just estimate the total top end cost with out labor:)

[pnut420]

Originally posted by WhiteBros400ex
Is it hard to rebuild the top end on a 400ex i had a base gasket leak and the top end blow up and i need to replace around how much does it cost and i know a good bit because i go to vo tech for small engine so i know how to rebuild things i just never took a 400ex apart motor wise. And would i need a new bottom end and new values for blowing the top end. Thanks for your help and im looking to put a 426 with a je high compression it had a wiseco 11:1 what ratio should i get and how many over to i bore for a 426 .080 thanks guys. Just estimate the total top end cost with out labor:)

Hey man hows it going. It is fairly easy to work on the top end. Best thing is to get a manual and it will walk you through. It is hard to say if the bottom end is ok without taking the top end apart.

As far as the 426, I would just resleeve and go 426 or 440. I had a 426 on stock bore and it seemed a little to thin for the cylinder. Id say cost wise you are looking at $400 for piston, etc... Or could do porting and hotcam stage 2, etc... fr around $700

[WhiteBros400ex]

Thanks is the 400 the whole thing including piston gaskets and bore thanks i need this done asap lol do i use the mnauel it came with or the like work book manuel thanks. Nice seeing you again and talking to you again.

[pnut420]

I didnt buy mine new, but yeah if it is the service book, then you should be good. It should show a walkthrew, if not you have the wrong book.

Boring is around $40 and I think the piston kit with gaskets is around $200. Then just leave yourself another $160 for taxes and other little things thats always pop up.

Are you going to get it running and sell it or keep it.

Im going with a YZ426 now and Im hoping this is the way to go