YZ 450 compression hole....

Thanks to everyone hear. I had seen posts about this plug falling out and was familiar with the TT piece that is sold to plug this hole.

Last night my neighbor dropped by. He was concerned with an oil leak on his YZF 450, 2004 model.

Thanks to you guys I was able to walk right up to the right side of the bike and find the leak. He bought the Yamaha part but has the better TT plug on order from a local dealer.

Just wanted to thank everyone for making me look so smart.

Is it just dumb luck when the plug falls out or is it owner related?

Many times it occurs when one of the metal clamps around the vent tube (on the right side of the frame) gets crushed and pinches off the tube. The head has nowhere to vent the pressure and the decompression plug will pop out. Newer years used rubber clamps on the vent hose so they go back to shape after being hit. I used to replace the metal clamps with zipties that I left fairly loose so that it wouldn't pinch off if it got hit.

Where is this plug you speak of? Can anyone point it out or put a pic up? I would like to just go ahead and buy the plug before mine pops out.

That is correct. The heads no longer have that bore in them, so there's no plug.

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