You can also order one yourself. Ebay has the entire kit for less than that. Not OEM but yours was OEM and look what happened to it!
Stihl MS390 locked piston
- Thread starter southland1
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southland1
ArboristSite Member
Was thinking about the aftermarket parts but didn't really know how good they were. Found a piston and cylinder kit on ebay for $26 shipped. Think since the saw has such low hours I am going to go ahead and get the OEM piston. If I was buying the piston/cylinder kit I would go aftermarket.
I've got three of them with the AM kits in them and no failures yet...
southland1
ArboristSite Member
Have already ordered the OEM piston but what does AM stand for, might try it on another saw down the road.
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After Market, can mean anything in a wide range in quality.
He means the real cheap stuff from China, which is a real gamble.
Other AM brands, like Hutzl,or other brands, at least have a name attached, so you have some reference.
He means the real cheap stuff from China, which is a real gamble.
Other AM brands, like Hutzl,or other brands, at least have a name attached, so you have some reference.
Huztl and Wangluo are the two main ones I use, they generally sell Farmer Tech products and are fairly reliable. Never had any trouble with pistons or cylinders, sometimes minor items have a little fitment problem. The last muffler I bought AM I had to do some filing on the bolt holes to get it to match up, no big deal..
southland1
ArboristSite Member
The piston finally came in and was installed a few minutes ago. Used Permatex Motoseal for the gasket. Took about 20 minutes to get it together, hope the gasket is good. Didn't buy the ring compressor so it was kind of difficult.
Motoseal is what I prefer. I think the factory uses Dirko but it's to me a lot messier than Motoseal. I generally replace the crankshaft seals while I have it apart but I usually deal with well worn saws, not a newer one as you have.
southland1
ArboristSite Member
Used the Motoseal on your recommendation, couldn't find the Dirko. Got a lot together. Still had throttle linkage, exhaust, and clutch to go. Realized I didn't put the metal intake boot clamp on and was going to try to get it on by taking the screw out of the clamp and placing the clamp around the boot and replace the screw. Dropped the screw and can't find it, also can't find my big magnet to search for it.
On those engines I usually put the intake boot and the clamp on the engine before installing the engine in the cradle, then just pull the boot through the hole in the handle. I've found that works the best for me. The handle is usually the hardest thing to install, for me anyway. Once you've done about 10 of them you can do it by habit...
southland1
ArboristSite Member
Yes, installing the handle was the thing I was worried about after disassembly. Turned out to be a lot easier than I thought. Of all the parts, the boot clamp was one of the first pieces to install, can't believe I missed it.
southland1
ArboristSite Member
Found the screw for the clamp. Took back apart to install the clamp on the boot. Was almost finished and lost a circlip. The one holding the flat plate on the brake linkage, it's at 48:30 of this video.
Was very careful trying not to lose the clip but it fell into the saw casing and is nowhere to be found. Was having difficulty installing the clip, wasn't enough room to get it to lock. Tried 7 or 8 times before I lost the clip. After clip was around stud tried pressing clip into place with a screwdriver and a small socket. Couldn't get it to lock into place.
Was very careful trying not to lose the clip but it fell into the saw casing and is nowhere to be found. Was having difficulty installing the clip, wasn't enough room to get it to lock. Tried 7 or 8 times before I lost the clip. After clip was around stud tried pressing clip into place with a screwdriver and a small socket. Couldn't get it to lock into place.
southland1
ArboristSite Member
Still have to get the circlip but it started right up on the second pull. Poured a little extra oil in the gas, filled the saw and then added 2 cap fulls of oil to the mix. Used cap from the Stihl oil bottle used to mix with one gallon of gas, think it's a 2.5 oz bottle. Thanks for all the help, especially a.palmer jr. and HarleyT.
Went back a few minutes later and it started on the first pull, hopefully my seal will hold up.
Went back a few minutes later and it started on the first pull, hopefully my seal will hold up.
southland1
ArboristSite Member
Saw has been repaired for a month but just got a chance to use it. Cut down 14 inch and 8 inch sweetgum trees. Saw ran like new even with the extra oil, used almost a full tank of gas. How long should it take the rings to fully seat so I can check the compression?
