please help me figure out what to do with my ms660.

[inbilya]

 

[inbilya]

I know someone is gong to say something about those carbon deposits, I know I should've cleaned my air filter more often, but is that the only thing that effects that? and how do I safely clean it out?

 

[inbilya]

also , when I put a finger nail across any of those lines on the cylinder walls, I cannot feel anything. on piston only one slight thing

 

[Brian Carlson]

I would clean it up and reassemble. I would check the fuel system. Sounds like it starts running strong and is starving for fuel as you cut. Might try the screen in the carb too. Small stuff can get by the filter in the tank and then eventually stop up the small screen in the carb.

 

[Marshy]

Piston and cylinder look fine IMO. Did you check the fuel tank vent?

 

[inbilya]

I have my options set to - watch this thread, and - receive email notifications. I would think I should be getting email when someone posts on this thread, but it doesn't happen.

 

[inbilya]

Piston and cylinder look fine IMO. Did you check the fuel tank vent?

where is it at ? and what should I look for?

 

[inbilya]

I will be checking that. thanks. what should I use to clean it up? should I remove rings and run some fine sandpaper on the piston? what is the best way to clean off those carbon deposits?

 

[inbilya]

I will also be plugging up the decompression valve hole, just to see if it makes a difference. it feels just a little rough. I suspect some carbon deposits got into it. Also isn't that what caused the piston wear? (carbon deposits) right?

 

[scallywag]

Just to be clear, this saw has been running on Stihl oil mixed @ 50:1 ?

 

[Bwildered]

Pic number 5 shows some damage on the top edge & side of the piston, plus there is what looks like metal fused to the piston rings, it has swallowed something small, but hard enough to put indents in the piston top edge.
Thansk

 

[pgdalton]

What is up with the ring ends and the locating pin?

 

[scallywag]

There appears to be material detaching from the piston.

 

[scallywag]

What is up with the ring ends and the locating pin?

I've been thinking the same, something looks odd.

 

[Bwildered]

The rings have just been spun around over the pins after disassembly.
Fanks

 

[scallywag]

The rings have just been spun around over the pins after disassembly.

What's with the grove in the ring that appears to be allowing it to seat on the index pin in that position?

 

[Cease232]

That's definitely out of whack. Id start with a new set of rings seated correctly.

 

[fastLeo151]

Lots of poor info and suggestions in this thread, what was the initial compression readings before it was disassembled? It's should have been pressure tested as well. If no air leak it's probably a fuel problem, which is what it sounds like.

 

[inbilya]

Just to be clear, this saw has been running on Stihl oil mixed @ 50:1 ?

yes and yes

 

[inbilya]

What's with the grove in the ring that appears to be allowing it to seat on the index pin in that position?

there is no groove in the ring. rings lost their orientation after coming out. what you see in the picture is looks odd I know, but it might be a reflection on the shiny surface of the ring or something. rings look perfect to me when I look at them with my own eyes and not the camera.