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LopeMX

Re-building 426 Engine.

3 posts in this topic

I'm in the process of re-building my YZ426 engine and I can't decide what to include. I've checked the valve clearences, and they check fine. The cylinder has good crosshatch marks. The head has your basic carbon build-up on it.

I was thinking of replacing the piston with a Wiseco (standard compression) piston. Can the valves be replaced with lighter replacements? Originally, I cleaned up the intake and exhaust ports that had some casting marks and that improved the performace a little. I'm looking to do a low level engine re-build to make it respond a little better and bring back some life into an old engine. All advice is welcome! :naughty:

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I would not bother the valves unless you have reason to believe they are worn.

Replace the piston/rings/rod bearing, the cam chain and tensionor and you should be good to go.

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I would not bother the valves unless you have reason to believe they are worn.

Replace the piston/rings/rod bearing, the cam chain and tensionor and you should be good to go.

I agree. The 2 piece valves are $19/ea vs about $60+ for the TI valves. I've heard the same thing about the problems with the 2 piece valves but have not seen anything posted from anyone who has actually had a problem with the valve failing on it's own and without some help from the piston hitting it.

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