Newto2stroke
New member
Hi Experts. I‘m not new to chainsaws but I‘m new to fixing them. I need your help please!!
My story: I bought my Stihl MS391 2nd hand and within a few uses it started to behave badly (first mistake but we all learn) It wad sluggish, cut out and no chain oil. So I decided to learn about it, watched loads of advice on YouTube. I replaced the chain oil system, now works fine. Then chainsaw stopped completely. Fearing I had done something wrong, I did the basics. Replaced the carb, air filter, better fuel with 40:1 mix. All these parts needed replacing. It would still not start. Checks spark and magneto, it was fine but lots of play on the shaft. So striped down engine; Crank bearing shot to pieces as were both oil seals. Cleaned up piston, replaced rings, new bearings and seals and reconstructed engine with all the right gasket materials, red gasket glue. etc, bought all Stihl parts as I’d heard about Chinese copies!!! Good compression now (held by starter handle and does not drop) and no play in the crank shaft after reassembled the whole machine. But again it won’t fire up. Sparks fine…Compressions good….So thought it was a fuel problem. Im trying to start it just as on YoiTube…Choke until takes, But don‘t even get that far.
So I‘ve noticed, after putting on full choke to start with 5 pulls, the spark plug is very wet with fuel and seems to be alot of fuel in the carb lower paddle. it almost feels it’s flooding too easily. Or maybe thats OK, just don’t know what to expect?
Please offer your advice for me to try and check and I’ll work the problem with you. Maybe a bit of a time lag as i’m in London. I’ve worked hard on this so don’t want to give up!! Cheers
My story: I bought my Stihl MS391 2nd hand and within a few uses it started to behave badly (first mistake but we all learn) It wad sluggish, cut out and no chain oil. So I decided to learn about it, watched loads of advice on YouTube. I replaced the chain oil system, now works fine. Then chainsaw stopped completely. Fearing I had done something wrong, I did the basics. Replaced the carb, air filter, better fuel with 40:1 mix. All these parts needed replacing. It would still not start. Checks spark and magneto, it was fine but lots of play on the shaft. So striped down engine; Crank bearing shot to pieces as were both oil seals. Cleaned up piston, replaced rings, new bearings and seals and reconstructed engine with all the right gasket materials, red gasket glue. etc, bought all Stihl parts as I’d heard about Chinese copies!!! Good compression now (held by starter handle and does not drop) and no play in the crank shaft after reassembled the whole machine. But again it won’t fire up. Sparks fine…Compressions good….So thought it was a fuel problem. Im trying to start it just as on YoiTube…Choke until takes, But don‘t even get that far.
So I‘ve noticed, after putting on full choke to start with 5 pulls, the spark plug is very wet with fuel and seems to be alot of fuel in the carb lower paddle. it almost feels it’s flooding too easily. Or maybe thats OK, just don’t know what to expect?
Please offer your advice for me to try and check and I’ll work the problem with you. Maybe a bit of a time lag as i’m in London. I’ve worked hard on this so don’t want to give up!! Cheers
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