I just purchased an 03 yz450f and it is my first thumper. I am in the process of replacing the crank, and was wondering how I go about ispecting the head to make sure I won't have any trouble any time soon. I already checked the valve seats by spraying fluid in and seeing if it leaked. What else do I need to check and how do I do it. Also how can you tell when its time to replace the valves, is it when the clearance gets tighter???
Head Inspection
- Thread starter sparkyz
- Start date
Pete Payne
MX-Tech Suspension Agent
- Nov 3, 2000
- 933
- 38
Get yourself a good service manual , I feel you will need it .
It's important to disassemble the head and carefully inspect the valve faces, seats, and measure the springs free length (or better yet the spring pressure on a proper tester).
As Pete pointed out the Yamaha service manual is crucial for doing this work.
As Pete pointed out the Yamaha service manual is crucial for doing this work.
- Thread starter
- #4
I do have the manual. I think I will take it into a local shop and have them inspect it for me and install new valve stem seals. The only thing I know about checking the seats is the fluid leak test, and I could definately measure the spring free length, but I definately don't have the trained eye to pick something out that is wrong. The shop said it would be $45, thats disassembly, hot tanking, inspection, replace seals, and reassembly. Thanks for the help.
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