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  1. #1

    1200 R XLT Engine Damage

    Hello all,

    My neighbor has a 1200 XLT yamaha and it started to run real rough. I checked the compression and the number one cylinder had zero. This engine had about 4 hours on it since it was rebuilt. I pulled the jug and found this damage. The cylinder and piston were new from Millennium Technologies when the engine was built 4 hours ago. What would cause this kind of scoring and ring damage? I really am at a loss for answers. I personally did the rebuild and I know it was done right and pressure tested fine. Could this be a problem with the oil system or carbs? Any help is appreciated.

    Thanks much,
    Eric Burke
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  2. #2
    It seems like the rings were crushed but the power valve doesn't drop into the cylinder at all.
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  3. #3
    why didnt you space the ring gaps 180* or at least 90*
    you had blowby crush the lower ring and then pushed the top ring up.

  4. #4
    cappa 2004 xlt1200's Avatar
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    the ring gaps are set by the pins in the piston. But it looks like the rings snagged the exhaust port mabie there wasnt enough of a shampher on the port not sure cause i had one do the same thing

  5. #5
    Moderator OsideBill's Avatar
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    Hard to see the top of the piston but it looks dark, my guess is lean seizure.

  6. #6
    gaz1's Avatar
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    yeah,i think it also looks like a lean seize,i took more pistons out my engine last year than anything else,i had a few that looked like it caught the exhaust port and pulled the rings round and a few that knocked the tops of the pistons off and even a few more after that!
    Since i have done the carbs to Osidebills specs,(which i should have done right at the beginning)i haven't had any problems and it's like a new ski now,actually,even beat a couple of 13r's lately.

  7. #7
    Me Hahn and Joe H204YOU's Avatar
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    Any time you rebuild you have to find the original cause,or it likely will happen again.Could have been junk in that carb.Hope this helps.

  8. #8
    i will be tearing into the carbs later tonight. Where can i find the specs for the 0sidebill carb mods?

  9. #9
    Moderator OsideBill's Avatar
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  10. #10
    Bill, what do you recommend for an aftermarket air filter set up?

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