Stihl 031av Can I re-ring or not

[gdavis]

I have a Stihl 031av that has been losing power. I pulled the saw apart and the pistion has very light score marks on the intake side of the bottom skirt of the piston. Your fignernails barely catches in the marks. Can that piston be reused with new rings. The jug looks like it is in excellent shape. Also does anyone out there have a repair manual and parts. I know the supply direct from Stihl is limited. My local dealer is of no help as the only thing he wants to do is sell me a new saw ( He is recommending a MS290 looks like a cheap plastic saw to me). I appreciate anyone who submits sound constructive responces. Thanks Glenn in Maryland

 

[Lawn Masters]

Welcome Glenn,

I believe you can re ring the 031, OR buy the new MS290, which is slightly newer. the MS290 has a decent track record, ask Stihltech, he'll tell you the same thing, its by no means a pro saw, but a very good homeowners grade machine. if you want lighter, but more powerful, and have the money to do it, buy and MS260. Just my $.02

 

[thompson1600]

I would put new rings on and let her fly. Light scoring on the intake side probably means something got in, if no other damage I'd re-use the piston. I'd also clean the carb and manifold to make sure nothing else comes through.

Tom

 

[Lawn Masters]

Plus new fuel filter, and lines as well just to be safe. while you're at it, I'd also recommend a new air filter to be on the safe side. a beat up air filter with big holes in it wont work for crap, new clean and in good repair will keep the saw from getting fed sawdust, dirt, or whatever else is in the air.

 

[stihltech]

compression

Did you check the compression, starter handle method. How does the piston fit in the bore?
Sorry to be picky, but there is a whole lot of diagnosis that was skipped.

 

[Marco]

Parts are getting spendy for them. If it still started decently and ran I'd tune it up and let er go and keep it for a back up saw and look for something a little more current.

 

[Stihl #1]

Some more things to check: a polished, scuffed look at the bottom edge of the intake side usually indicates over-revving, saw was running too lean. Vacuum/Pressure test the crankcase to be sure the seals are good, and this saw is a few years old so it would be best to replace the seals if you are doing rings anyway. V/P test will also make sure gaskets and impulse hose are OK. If intake side is dull and all the machine marks are worn off, then long term dirt ingestion is the cause, which may have worn the ring grooves, so if the cylinder is not too bad, to fix it right would mean piston and rings. The piston will have a smaller diameter at the bottom allowing it to rock and not seal the intake port as the piston goes down to pressurize the crankcase prior to the transfer ports being opened. This will allow spit-back and lean running conditions also. Lean running can be from an air leak that allows air in somewhere other than the carb, or a fuel problem that restricts fuel from mixing with all the air going through the carb. Verify that all are OK. If piston is not dirt damaged, use very fine crocus cloth to buff down any score marks, and run the saw a little rich to break it in, and you should be right. I have an 031 manual, so I can scan a few pages and e-mail if you can't find one, and know what info you want.