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jay3and88

YZ 426 Bore out or buy new cyliner?

4 posts in this topic

Hey guys and gals, I've got a YZ 426 that I have to do some work on the cylinder, I need to eather buy a new cylinder or bore it out and sleeve it to fit the new piston. Someone had told me that because of the nickle coating or what ever it's called, if I bore and sleeve I could loose power, Does anyone know if this is true and if so would you really notice it if your not on the track. I'm not a Pro by any means but I do run the bike hard.

It would cost less to sleeve it but would this hurt reliability. Could I bore it out to be a 450?

Just wondering if anyone has had to deal with this.

Thanks,

Jay

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It can be punched and renaik'd to run a 97mm piston = yfz444.

Did this to my old 2000 years ago and never had any issues. Made it pull a little better down low. Mid and top felt about the same.

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Did you have to change anything else, cams or anything?

Nope. All the stock internals remain.

I installed the 03 450 decomp cam while I had the motor torn down, but it was not necessary.

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