96 xp Burning piston on mag side

[xpdale]

Hi Guy's
Have been struggling with this ski for a while going through the carbs over and over thinking I am missing something causing it to burn the mag side piston.(I get about a season and a half before having to replace the piston) Also the carbs will not adjust.
Making changes to the slow screw didn't make any difference and the engine wants to run fast even at idle. thinking air leak' blocked off the engine per the book and pumped 10# pressure into it. Did not seem to hold, pressure reduced slowly cannot hear a leak. Could see air bubbles pushing up slowly through the crank oil line.
Do you think crank seals? was trying to avoid pulling the motor.
Any ideas?
Thanks for your help.

 

[Dr Honda]

A bad crank seal will take out a top-end fast. If the crank is the original... that's probably the problem.

 

[xpdale]

A bad crank seal will take out a top-end fast. If the crank is the original... that's probably the problem.

Thanks Dr Honda,
Yes, original seals
Will be pulling the motor.
Thanks again for your help

 

[xpdale]

Hi Guy's
I pulled the top end off and found one piston with a hole trying to burn through. Have not seen this before.
Found the top edge of the cylinder where the o-ring sits collapsed. Could water getting in done this? I have the motor out for seals just wondering if I should go with a rebuild?
Your help is appreciated.
Thank you,

 

[AdamXP800]

I can't see any of the pictures



96 XP800!
Keep the 2 strokes alive!

 

[xpdale]

Tried pictures again,
Hope they work this time.
Thank you

 

[racerxxx]

I'll assume you've never gone thru the carbs. Does the ski still have gray colored fuel lines? That carb is so lean the fuel is not cooling the piston and you've melted the exhaust side of the piston crown clear off to the ring land.

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[racerxxx]

I just looked at the pics on a PC, WOW...never saw the o-ring land do that before on cylinder. I personally wouldn't run that cylinder. And If it were me, I would be in for a full rebuild.

 

[xpdale]

Thank you, that's kind of what I was thinking. I have been through the carbs many times replaced the fuel lines long ago. Could not figure out way it wouldn't adjust, just to much air leaking in.
Thanks again for helping me through this. Have heard SBT has a good rebuild any suggestions?

 

[racerxxx]

If your going to replace the entire engine then sbt would be your fastest turn around. I put two in a guys challenger a few years ago and they're still going strong.

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