What happened to my MS390?

[pioneerguy600]

Depends on what you call ran. It started and ran long enough to choke out. If I had been faster I could have released the choke and it may or may not have continued to run. I took the choke off after it stopped and tried to start it again and it wouldn't hit and felt like low compression after that. It's back apart now, cleaning it up again...The circlips and the ring locating pins were both intact. Just looks like the casting broke...

You missed the part where I said the ring broke upon startup. Many things can happen to these saws very quickly, they don`t need to run for hours for damage to occur and I know you did not want to believe the parts broke but they did. The only way to see what broke is to pull it apart, which you have now done. When you come on here and ask for help you will get both answers and questions , you must do the leg work but don`t disregard the help offered.

 

[a. palmer jr.]

I kinda knew I was gonna have to take it apart after I checked the flywheel and re-installed it and it wouldn't turn. I don't know if I mentioned it but the rings are fine also . The piston and cylinder sure are trash though. This is actually the first AM cylinder kit I've had any trouble with and I can't remember how many of them I've done over the years. No, I value the opinions I get on this site and have received a lot of helpful advice. This saw is sitting apart right now and the next project is a Jonsered 2240 that's been in about three repair shops and nobody can get running right. I'm assuming that the owner of this saw used ethanol and cheap oil in it like most people around here do...

 

[lone wolf]

Cheap Chinese junk strikes again, it works until it doesn’t. So you get to do all the extra work for the customer for free so he can save money on cheap parts?

That stuff gets tiring fast don't it?

 

[a. palmer jr.]

That stuff gets tiring fast don't it?

Actually I don't mind it at all, even on the clam shell saws except in the winter it's kinda cold getting out there. If I didn't like messing with chainsaws I would just look for something else to do. Most of the people that own these saws tell me there's no hurry but most of them don't want to spend a big bunch of money on a saw like the 290 when there's an Echo dealer less than 3 miles from me that sells the 590 for around $400. Lots of them have gone that route but if they trade in the 290 I still get them over here to rebuild..
One thing I haven't tried is the 066 kit saws, mainly because of the initial investment in the project. I figured if I wait long enough a Stihl 066 will show up in poor condition and I'll get it to mess with...