Meted piston?

[Stihl95]

Hi everyone I recently noticed my ms361 was running rough and decided to take a look at the piston and rings. When taking the cylinder off I noticed that the top of the piston looks melted? I could use some help finding out what happened.. thanks guys!

 

[kenton.a.frank]

Sign of detonation... usually from poor fuel or water in fuel


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[Stihl95]

Sign of detonation... usually from poor fuel or water in fuel


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Hmm makes since I let the saw sit all fire season.. Do you think I could save the cylinder? The walls look okay but the top has some pock marks. Could I polish that out?


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[kenton.a.frank]

Hmm makes since I let the saw sit all fire season.. Do you think I could save the cylinder? The walls look okay but the top has some pock marks. Could I polish that out?


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Is that reflection on the sides? If so I’d grab a oem or meteor piston with cabers drain the fuel and change fuel filter and keep going.


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[Stihl95]

Is that reflection on the sides? If so I’d grab a oem or meteor piston with cabers drain the fuel and change fuel filter and keep going.


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Yeah that’s just some reflection. The cylinder looks good other than the top. I was hoping I might be able to hone it or polish with scotch brite? I already went and replaced the piston and cylinder with a oem spare I had.. Im just hoping it doesn’t happen again lol


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[kenton.a.frank]

I wouldn’t worry too much about cleaning the top. I mean feel free to but the piston doesn’t hit it. You could clean it down some but if you are taking metal away you would be lowering compression slightly if you are bot taking equal metal off the bottom. And I. Doing that you will be changing timing slightly.


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[Stihl95]

Hmm I think I’ll just let it as it lol thanks for the help I was really worried that it might happen again!


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[Stihl95]

Hmm I think I’ll just let it as it lol thanks for the help I was really worried that it might happen again!


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[Mad Professor]

Cheap gas. Had you done a base gasket delete or anything to raise compression?

 

[deye223]

I would drop the jug for 0.040 recut squish band to give around a 0.020 squish band and port and not look back

 

[AlterEgo]

You should be able to hear that damage happening.

 

[deye223]

Hard to hear in a 2-stroke doing 9 10000rpm especially if you don't know what to listen for

 

[Stihl95]

I didn’t hear anything other than just a rough ideal. I could not keep it running. I thought maybe the carb just needed to be tuned but I put it back to factory and it still wouldn’t ideal.

On another note I have completely rebuilt once but other than that and a muffler mod this saw is pretty stock. I personally love the 361 she my favorite thinning saw.


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