Stihl 362 C-M scored piston

[pwheel]

Question: If the MTronic or similar autotune system malfunctions with a lean mixture, how would you know it before the engine gets toasted?

 

[Cobby08]

Not 100% on your question but I assume you are asking if BOTH happen at the same time, it would be just like any other saw. It would probably lean seize/score. The MT/AT systems aren't really designed to compensate really for poor lubrication.

 

[pwheel]

I just wonder if a malfunctioning autotune system can lean-seize a saw regardless of oil/gas ratio.

 

[Cobby08]

I guess malfunction wise yes it could. I am not sure about the AT but I know the solenoid on the MT is a normally open solenoid so if there is a failure its just going to flood the chit out of it.

 

[Ryan Browne]

I bought my first "pro" saw a few months ago, a used MS362 carb version.
I buck with it, leaving it at 3/4 throttle or more for 5 mins or so, just moving down the hardwood logs and letting it self feed.
I may spend an hour like this.

I mix stihl orange bottle at 40:1 with non ethanol fuel.

This thread has me all worried.
I'm going to inspect the piston tonight.
I bought it to treat as a professional grade tool that would save me time.

This would really sour me on Stihl if I cant use it without worry of it getting damaged by normal use.

I'm with cobby08 on this one. Idle or WOT. No partial throttle.

 

[huskihl]

I guess that's another reason to dislike limited coils. If a guy listens for 4 stroking in between every few cuts, he's normally safe. Can't do so with a limited coil

 

[Travis-Mc]

I got the cylinder all cleaned up. It cleaned up nicely. I did hit the top of the chamber with the end of my mandrel, but I don't think it'll affect anything. You can see it in one of the pictures and in a reflection off the cylinder wall.

The squish with the new piston is about .010 without a gasket, .025 with the oem gasket, and .015 with a pop can gasket. I was hoping for .018", so I'm thinking of either making another gasket from some .008 aluminum, or cutting .008" from the piston to make a pop-up piston. Is it worth trying a pop-up for only .008" removed? I have a lathe and it would only take a few minutes.

Should I just use the OEM gasket? From my calculations, using an .008 gasket instead of the oem one will decrease the combustion chamber size by about 4-5%. Maybe I'm doing the math wrong, but I would expect about a 4-5% increase in compression, so 6-7 psi. Is it even worth it for that? Does a 4-5% increase in compression mean 4-5% more power?

Now if I do a pop-up piston I should get quite a bit more gain in compression, but I have no idea how much and don't want to do any more math.

 

[MustangMike]

May want to try some flashing, usually about .010.

 

[Travis-Mc]

That's exactly what I thinking. $5 for whole roll and I'll only need a few inches. I was going to lightly sand it to see if I could get it to .008"

But now I'm leaning toward running no gasket and doing the small pop-up. Not sure yet.

 

[huskihl]

I'd run it with the OEM gasket. I don't think you're going to be able to feel the difference by only removing a half of a gasket in squish clearance. You did a nice job cleaning up your cylinder. That looks really good

 

[shadco]

Doesn’t cost much to try it with the stock gasket less risk too. You can always go thinner later.

.

 

[Travis-Mc]

Well that sounds like the safe thing to do, but where's the fun in that? I thought for sure you guys would say go for the pop-up, and you might as well port it a little while you're in there!

Once I have it back together, I doubt I'll take it apart again unless I have to.

I just got a 261 c-m, and would really like a 462 c-m instead of this saw, but I really don't need it, so I like the idea of trying to mod this saw a little so it doesn't just have .7 more hp than my small saw. But maybe you're right, use a stock gasket and a muffler mod that can easily be undone in case I decide to sell it. I'm on the fence.