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  1. #1

    No compression in rear cylinder

    I put my 1999 Yamaha XL1200 in the water on last Sat. could not go over 30 mph. It stalled a few times. I pulled the seat and looked insude engine and battery compartments for water or a loose spark plug,none found. I drove it to marina and got some greenish blue gas treatment. The 2 other guys we were riding with said it was bad gas. so I drove it for 1/2 hr. Pulled out and found that I never had the drain plugs installed at rear of machine. Did a compression test 120-125-0. The plug had some metal filings on it and the gap was closed 0% upon removal. I think it could be piston rings,hole in piston or could it be reed valve ?The piston does move up and down.

  2. #2
    Was there a lot of water in the hull? Sounds like #3 sucked a bunch of water in and blew. Piston, rings and cylinder...

    Only way to know for sure is to pop the top and take a look. If you saw metal filings though it does not sound like you lost a reed.

  3. #3
    I was surprised when I saw very little water in hull but I did find the drain plugs out when I pulled it out on boat ramp. I guess I will have to pull the head off. Thanks for your advice.

  4. #4
    I replaced the cylinder,piston,rings,wrist pin and wrist pin bearing. Could reed valve be damaged? How do I make sure the Oil/fuel is getting to this cyl.?Should I do this D plate thing?

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