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  1. #1

    Join Date
    Apr 2010
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    South East
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    99' XL1200 Limited Power Valve Hitting Piston

    I'm doing some work on a 99 XL1200 limited. Long story short, after a new battery and start relay (not related to the later mentioned) the rear cylinders compression is 25psi. The other 2 is 120+/-... both being the same. Tore it down and seen where all the pistons have been rubbbing the power valves. The rear one looks like it touched a little more maybe causing the damage. There is also some oil in the hull so I have to see where that came from. I know the owner filled the tank slap full and there is a leak where the rubber fill tube goes on the tank.

    Anyhow, Whats the proper way to adjust the lower position to keep the valves from hitting the pistons. I read a thread about this but nobody explaned how to adjust this. Is it adjusted with the cables? I removed the whole plate that holds the cable ends so I haven't messed with the adjustment. Also, the damage was not as bad as the photos in the thread I mentioned. (rings were not bent)


  2. #2

    Join Date
    Apr 2010
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    UPDATE!!! The cause of rear cylinder/piston failure was due to the oil line comming off the carb.
    After tearing into it I found that the piston rings had been rubbing the power valves on the first and third cylinders. The cylinder itself supposed to limit the travel of the valve so this dosen't happen. Depending on which part has worn, the cylinder and/or powervalve must be replaced. I used my drum sander on a die grinder and took some material off the valve keeping its same shape and form.
    I'm hoping to take it to the lake today and make somebody happy!

  3. #3

    Join Date
    Jun 2014
    Location
    Tulsa, OK
    Posts
    1

    Lightbulb 1999 Yamaha. xl. 1200 Ltd power valves

    Quote Originally Posted by JH1200A1 View Post
    UPDATE!!! The cause of rear cylinder/piston failure was due to the oil line comming off the carb.
    After tearing into it I found that the piston rings had been rubbing the power valves on the first and third cylinders. The cylinder itself supposed to limit the travel of the valve so this dosen't happen. Depending on which part has wo#2 rn, the cylinder and/or powervalve must be replaced. I used my drum sais tightder on a die grinder and took some material off the valve keeping its same shape and form.
    I'm hoping to take it to the lake today and make somebody happy!
    Just bought a 99 1200. Removed exhaust and found cat looking like a snow cone. So I removed it. Installed a d. Plate and chip. Removed oil pump and went premix. Removed power valve covers. And servo linkage. Manually turning the pulley I could see there was a problem. As #3 started open, #2 was not moving. As# 2 started moving #1 was not. Lots of play. #1 & #2 would never open completely. So I made new couplings and clips. Now all is tight and all 3 valves open completey. When guys say they don't feel the power band like they used too. I would say it's due too the power valves not opening completey. Anyway my 2 cents worth. Although I did save 100.00 on clips and couplers.

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