How to Redo your Top End: Remove and Lap Valves on Yamaha Moto 4 YFM225 YFM200 DX - Part 4

Still working through challenges. After hooking up the leak down tester in the previous video I pulled the cylinder head. It's time to really inspect the valves, pull them, lap them, clean them... I want to get the compression above that 75PSI. As a point of reference, when I started the PSI was 48. After rings and a cylinder it's now 75PSI. Still too low.

On the Moto 4's the cylinder head is one cast piece which makes it interesting to get the rocker arms or cam shaft out of the way to remove the valves. I found two good techniques for doing so after some trial and error with either an M6 or M10 bolt and some scrap metal to pull the rocker bolts out.

The specific ATV I am working on is a Yamaha Moto 4 1988 YFM225.

I'm learning as I go but enjoying it. I welcome your thoughts in the comments as I work a bit then digest what I observed and move forward.

As an aside, I am not a mechanic and while I may do something a particular way, it may not be the best way or even the correct way. Follow along and learn as I do.

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Видео How to Redo your Top End: Remove and Lap Valves on Yamaha Moto 4 YFM225 YFM200 DX - Part 4 канала Vermont Life