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jrcgaf364

[B]Wrist pis size?????[/B]

2 posts in this topic

Is the wrist pin size in a 99yz400f the same size as the 00yz426? I have my motor bored out and i am rebuilding it...dont know which crank i need? :applause:

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From what I recall the 400 has a smaller wrist pin than the 426.

Back in the 426 days the 400 guys were doing big bore kits with the 426 cylinders but had to switch cranks as well from what I recall.

If you are building this thing up from scratch then I would definately go with the 426 crank and a 426 piston, that way the big bore could use all OEM components which are more reliable, and you dont have to run such tight piston to cylinder wall tolerances to pull it off.

It is common knowledge now that the guys who are using JE or Wiseco pistons in big bores are running much tighter tolerances to eliminate premature piston slap.

The back side of tighter tolerances is more heat so you may find that you need to run Fluidyne radiators to keep it cool.

My big bore is being set up with .030 (.0012 in.) tolerance but I have Fluidynes to keep the heat in check.

Ill let you know how it gos.

With a 426 crank and cylinder you can safely take it out to 446cc with no other mods required.

That is a safe 2mm overbore (97mm piston) and I have already had a motor with that overbore in my bike for 3 or 4 years now, I am just building another brand new big bore motor to get me by for a while, while I build a stroker/big bore as the next project.

Im thinking the Falicon path seems like a fun one to venture down.

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