My saw fills the cylinder with fuel while in transit. Is there a breather on the fuel tank some where.
is there a decent non chinese replacement engine for a 391./?
Husqvarna
Purchased 391 July 2018 used it for about an hour in august, no probs,heaps better than my old 039 that it replaced after 20 trouble free years. Last sat, Feb23,used the 391 and my ancient 024 to cut up a gum tree that came down at xmas,024 as usual no probs, 391 difficult to start,kept flooding,in the end full throttle and kept pulling till it started. It ran well for about 40 mins then DIED,hole in piston!!Used the same fuel,mix,stihl oil and 95 ulp, in both saws and same cutting technique. Can only guess that carby set too lean at factory,faulty crank seal,or just a crap chainsaw??? Any ideas??
if your exaust screen was plugged that will create an overheating piston on any two stroke. Too much mix can also create a slower burn. A lean mixture will do the same.
Will a piston and cylinder from a Stihl MS390 work on a Stihl MS391 ?
I need to know this too
The pistons are VERY different. The 391 is a strato engine.
Three are also two different MS391 cylinders. The intakes are different.
Hi, I noticed Luke and Mike have had trouble with pistons and air leaks after very little use with MS391 but have then been told it was their fault, that they over loaded the chainsaw, so it would not be replaced under warranty. We have a very similar story. Just wondering if anyone else has had this same issue and been told the same story by Stihl?
My son bought a MS 391 in June2017. We have used it about 10 times. It was used mainly with Stihl oil and standard fuel, using the correct 50:1 mixture. Unfortunately I used the saw on a couple of occasions but used a reputable oil again 50:1. When I purchased a new MS381 I mentioned to the dealer that the MS391 was always hard to start from the beginning and after each cut would idle after finishing a cut would idle normally but when increasing the revs for the next cut it would stall after which it immediately started next pull. He said it sounded like an adjustment to the carby would fix the problem. Unfortunately he came back later and advised that the piston head had been scored and the piston needed replacing at a cost of $500. Spoke to the Stihl Service Representative who stated that the foil I had used was not appropriate for the saw and had damaged the piston. So no warranty. The manual states that only high-quality two-stroke engine oil -referably STIHL HP,HPSuper or HP Ultra, which are specially formulated for use in Stihl engines. HP Ultra guarantees high performance and a long engine life. Nowhere in the book does it state that if you use the incorrect oil you will seriously damage your engine.
A friend who is mechanic by profession doubted the story Stihl had spun also has a MS391 and purchased it shortly after my son's purchase. We were cutting timber last week and his MS 391 made a bang, blew a lot of smoke and died. His dealer advised that the piston had blown. My friend had used Stihl oil in his fuel mixture and yet still the saw failed. I think the 391 is a dud and Stihl are not a respectable company to deal with as their warnings are not adequate and I strongly suspect their saw is not firt for the purpose of cutting wood in our environment.
There seems to be quite a few cases of these stories given by Stihl. In our case we took it to Victoria Consumer Affairs and Stihl were made to refund us the full cost of the chainsaw.
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