Piston Question

Arborist Forum

Help Support Arborist Forum:

otisdog

ArboristSite Lurker
Joined
Jun 23, 2014
Messages
23
Reaction score
4
I've got a MS 361 that has a recently replaced OEM piston and cylinder that has 2 to 3 hours on it. I pulled the muffler so I can open it up a bit, and found what I (a chainsaw novice) thought was premature wear to the right of center on the piston. Is this normal? The shop that replaced the P&C did it on their dime because they straight gassed it while it was in for service. 93 octane non ethanol with stihl oil @ 50:1.
Thanks
IMG_3811.jpg
 
Joined
Nov 4, 2019
Messages
796
Reaction score
1,170
Location
Tacoma, WA
Doesn't look like it does it.
Looking at the pictures again, the cylinder does look pretty clean. That doesn’t necessarily mean anything either way. They could have just cleaned the original cylinder up (if they caught it in time) and replaced the piston and rings. Seems like a shop would want to fix it as cheaply as possible if it’s on their dime. Of course this is all speculation based on the evidence at hand.
 

Yukon Stihl

Addicted to ArboristSite
AS Supporting Member
Joined
Jan 26, 2011
Messages
1,483
Reaction score
2,220
Location
Yukon Canada
Talk to the shop
If they wash their hands of it then it's time to pull the jug.
If you have the tools vac and pressure test before taking it apart.
You could adjust the squish while you have it apart,compliment the work you were going to do on the muffler
 

stihltech

Addicted to ArboristSite
AS Supporting Member
Joined
Mar 23, 2002
Messages
2,671
Reaction score
442
Location
western NY
On this age of saw, a pressure/vacuum test is mandatory. I replace the carburetor also. You have a very light lean seize. Dirt from reassembly will not do this. Start looking for a lean condition from the fuel up.
 

cookies

Addicted to ArboristSite
AS Supporting Member
Joined
Nov 26, 2020
Messages
1,865
Reaction score
3,309
Location
Crawfordville
damaged piston from heat expansion, the remaining ridges on the skirt appear to be wearing down as well. I can see the damage also forming beyond the right side of the window s well.
Try your hand at warranty again or snatch that cylinder off and install another piston yourself. Either way the H needle needs adjustment and luckily there is a lot info in here on how to do it.
 

Latest posts

Top