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  1. #1

    Question gp1200r or xl 1200 limited 3rd cylender burned up sparkplug beat up??

    i have a xl1200 limited 66v engine im working on bought with 3rd cylinder burned up. I bought a new piston and put a cylinder jug from a gp1200r changed the power valve connection . had it running broke it in.. then opened it up got to 55 shut down. now spark plug is closed and beat up like it was compression . have no idea why. rod had normal play in it when I put it back together. maybe got to hot and extended hit spark plug? I bled the oil line. now I guess I need to rebuild carbs and go to premix and start all over. so now I need new parts and some advise to rebuild , if anyone has any jugs or pistons or the best things I should buy or advise. .help would greatly be appreciated . can call or text me anytime 817-706-6655

  2. #2
    silver93t's Avatar
    Join Date
    Jun 2012
    Sure you had the right plugs in it? One time in a rush i threw the wrong plug in my waveraider. The reach was too long and the piston hit the spark plug. Luckily there was no other damage.

  3. #3
    Yamaha artisan Cutlass's Avatar
    Join Date
    Oct 2010
    Madison, WI, USA
    Last time I had a smashed spark plug, the crank bearings came apart and got sucked up into the cylinder. Beat the head and spark plug up pretty good.

  4. #4
    thanks for the replies. but yes I did have the right spark plug in. I think it could be the crank bearing , although I checked it before I rebuild and it was fine. I am thinking maybe some particles or shavings got in and beat up the spark plug. I am going to tear it down and start all over . probly rebuild carbs although ski seamed to idle fine and respond good. idk . I am also going to go to premix oil. maybe change the head. any advice would be great. thanks for the responses. I still haven't bought parts yet. not sure if I should use wsm or prox or oem..

  5. #5
    Probably have an air leak or its your carbs but it probably leaned out. Put a new crank in if yours is damaged and put new crank seals in. Go oem

  6. #6
    Quote Originally Posted by ctct2118 View Post
    Probably have an air leak or its your carbs but it probably leaned out. Put a new crank in if yours is damaged and put new crank seals in. Go oem

    Unless somehow the cylinder was starved for oil. Either way it sounds like your new piston just became a paperweight and the pieces trashed the head and piston. Time for a new head, piston, complete tear down, and a leak down kit. Good luck.

  7. #7
    thanks for the advise. hopefully the crank is still good. maybe just some particles hit the sparkplug. i guess i will know when i take it apart once again. that exhaust is a pain in the but. but im getting good at it now.. sooo much paractice.. lol

  8. #8
    dockwalker's Avatar
    Join Date
    Mar 2010
    On the water near Belhaven,NC
    AMEN to that exhaust! Biggest POS I've ever owned.Still screwing with it.Japanese technology might be great, but you need an arm 4 ft long and 2 inches in diameter....with a crossed eyes! I've been tempted to open mine up with a sawzall and clamp it back with sink clamps!LOL Anybody done this?

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