440 Big Bore KIt
#1
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I just purchased a basketcase 2003 400EX. The original piston had blown and the engine was disassembled when I bought it. It came with a Wiseco 440 big bore kit with 12 1/2 to one compression piston. Does anyone have any advise on installing? It looks pretty strait foward but I'm concerned with that high of compression that there are other thing which may need to be changed. Valve springs? Head studs? Rejetted? Will high octane fule be necessary? Aside from the top end and jug, should the lower end be disassembled for cleaning and inspection?
#2
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It would not hurt to inspect the bottom end. The 440 12.5/1 pistons really like pulling head studs and causing the head gasket to blow. There is a few companies that sell heavy duty studs. I think Curtis Sparks is one of them. You will probably need to run a 50/50 mix on fuel also. The valve springs will be fine, until you buy a "regrind" cam, from somewhere like Web.
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