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hondacrf250rrr

yz426 with yz450 crank? need help quick

4 posts in this topic

is it possible i was looking at the bore x stroke and they both have a 95mm bore but the 450 has a longer stroke if i put that crank into my 426 would it make it a 450 and would it work. would else would i need to convert it. would the carb work still?

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is it possible i was looking at the bore x stroke and they both have a 95mm bore but the 450 has a longer stroke if i put that crank into my 426 would it make it a 450 and would it work. would else would i need to convert it. would the carb work still?

Assuming the 450 crank would fit inside your cases,with the longer stroke the crank assmbly might have a larger diameter.

I would say you would also need the piston for that year of crank assembly.

Since the 426 has a shorter stroke it probaly has a taller piston.

I would guess that if you tried to use your 426 piston with the 450 crank the piston would hit the bottom of the cylinder head.

This is just a guess.

So dont run out and buy that crank and piston assembly.

If it did work I see no reason the carb wouldnt work other than it may need jetting changes.

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assuming the crank fits into the cases, you could put a spacer between the cases and the cylinder. its thickness needs to be 1/2 the difference between the strokes of the two cranks. you might have to relief cut the cases/cylinder where the rod makes its closest approach as the throw will be a little wider.

i can't imagine it would be so thick as to require a new(longer) camchain but...

also, you need to determine whether the ends of the cranks are similar...it would suck to make the combo work mechanically on the inside only to find out you can't bolt up the externals like flywheel, etc.

if you're lookin' for more power, cams and porting would be waaay easier.

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