First 4 stroke rebuild experience

No longer intimidated by a 4 stroke. I took my project 2008 yz450f down to the last nut and bolt. Also removed all the valves replaced all valve seals and cleaned the head. Valves were still sealing. The piston, crank and bottom end bearings replaced. In about 25 hours im sending the head off for new seats and recut and replace the valves.

For the people that are scared of a 4 stroke. They are super simple to rebuild with a manual. The hardest part was doing the torque on the head bolts. The 180 degree turn was hard with the motor out.

Make sure and order a hot cams shim kit and a offset feeler guage.

Overall fun easy project.

How much did this set you back? I have a 09 450F that's got about 75 hours on it so it's gonna need a refresh here soon.

I'm not ready to rebuild a 4 stroke yet. I bought an old 2 stroke I'm gonna start on. 92 YZ250 that's in ok shape but doesn't run.

I got the oem piston ring and gaskets from partszilla about $150 with head rubber gasket. Oem Crank was new ebay $325. Bearings and stuff i forgot. About $700 ish. Its really not hard to do. If your a techy person, its really a fun project. I even pulled the valves out to do a good cleaning. I removed and reinstalled them without a fancy valve tool.

I meant total was 700ish

Nice. Can you tell a difference in how it runs.

It stopped running on me in mid flight. Iy jumped timing. Luckilly no damage. It was from an overused cam chain. I have not run it at the track yet.

hopefully you cut new valve seats for the new valves.


opps sorry I missed that you said you was sending the head out, sorry my bad. glad you did!

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