Hey guys. I just picked up 2 029 supers the other day. One runs great the other won't start. The previous owner said it gets spark and he replaced the fuel line which had a crack in it. I pulled the muffler off to check the piston and there are a couple score marks but it doesn't look terrible. The 029 that does run feels like it has way more compression than the one that doesn't when you pull the cord. I got both these saws for $200 and I'm considering fixing the non running saw and selling it. Is there any way to tell if the piston is junk and has no compression? Also any idea how old these saws are? Thanks.
A compression tester will tell you if the saw is healthy or not. Something like this one will do the trick for not a lot of OTC makes a nice one too. Alternatively you can post a pic of the scored piston and let some of the skilled saw surgeons on here weigh in on wheather it's smoked or not. What about keeping the non runner for parts?
Pour a little mix down the plug hole and try to run it. If it runs for a couple seconds, then you have a fuel delivery issue. If compression is noticeably bad by the arm test, you might need to dig deeper and pull the jug.
Here's a pic of the piston. There's a score on the right and left side in the pic. It looks like there is a score in the middle but that's just the glare.
Didn't really look at the ring. Like I said in my original post the saw that doesn't run doesn't quite have the recoil like the saw that runs fine. I'm not sure if it is a fair comparison.
from what the picture show the piston looks good at least for starting the saw , now you must check the rings and the cylinder also good compression is a result of three parts cylinder + piston + rings for sure a good compression tester will help but if you dont have one then do this go and buy just a new piston ring and put it inside the cylinder then measure the gap of the ends of the ring , if this gap is from 1 mm and over you need new cylinder , if this gap is lower from 1mm then the cylinder is good as much close is the gap as more good is the cylinder
Thanks for the info guys. Not sure I wanna tear into the saw that much. I may try the simple things first.
Good plan. Piston looks good. Check the ring/s and see how they look. If they look as good as the piston, compression should be fine. A saw has to have pretty low comp for that to make it not run. Since the piston looks good, I'm betting this is a weak spark/bad coil or fuel delivery/carb issue. I'd do what cnice_37 said and dribble a little fuel mix in the spark plug hole or into the carb and see if it at least tries to start that way. I'd also confirm for myself that it has good spark. Spark should be fat and bright blue. If it's white or seems weak the coil or plug is probably bad.
Yes...... Crank it until you can see the piston through the exhaust port with the muffler off. The ring or rings, i dont remember if the 029 had 1 or 2, will be near the top of the piston. If the ring/s looks nice and smooth like the piston does then it's probably fine.
So just had the saw tested for compression at the local shop. Only 90 psi. Looks like it'll just be a parts saw.
You could put a 49mm bore 039 top end on it. Can get just the top end or a whole short block. AM prices are low.
Well the thing is after I put all this money into it how much will the saw be worth? Personally I won't need it.
An 029 will fetch 2 bills all day long. Not from me, but they look clean. Sell it for $50 as is and buy some beer.
Another thing before you give up, check if the ring(s) are stuck. Simple thin flat head screwdriver through the exhaust port.
Shoot an aftermarket 49mm 039 piston and cylinder are between 40 and 50 bucks on fleabay. 49MM Cylinder Piston Rebuild Kits for STIHL 029 039 MS290 MS390 MS310 Chainsaw It's a direct bolt on. Those saws look like low hours units I bet crank and bearings are fine. Send it my way I'd happily pay you 50 bucks for it and rebuild it. It's probaby not worth much more than that as a parts saw.
