Outdoor Power Equipment and Small Engines - Chain Saw Needs Repair

I have a heavily used 3 year old stihl MS290. It won't start.
It has had no major repairs.


There is good fuel in the tank.
The air filter is clean.
It gets a spark.
I blew the feul line clean.
I checked the fuel filter...looks good I guess..I blew air
through it.
The carb has NOT been rebuilt. I saw no visual tears
on the fuel pump diaphram.
It has fuel on the plug.
The plug is new.
The plug is gapped correctly.
The exhaust port shows scratches on the piston.
I can not really tell if the compression is adequate.

Are any scrathces on the piston enough to cause the engine from starting ? How much scratching is OK ? Is there an easy way to test the compression without a tester ?

I found piston kits on ebay for around $26. They are made by Golf. Any good ? Does it really matter if the piston kit is not made or sold through the manufacturer ?

Boy that's kinda a hard one to answer correctly.That's one of those location things.But since I'm not there to see the scratches.I'll tell you how I'd go about it.Take a small piece of wood or a screwdriver put into the exhoust/intake ports and (very lightly) run it over the piston,see if you can "feel" the scratches.If you can feel them any at all,it's time to disassamble and get new parts.

As far as the compression isue goes,hold your thumb over the spark plug hole while cranking on the engine.If it tends to forcefully blow your thumb off with a "wooshing" sound,it's OK.

Guy is right about the difficulty in advising you without having firsthand insight. You'll have to use your best judgement. Also, you'll want to check that the ring(s) are free in their respective ring lands using a small, flat-blade screwdriver and pushing inward on the ring(s) into the land(s). If you are not able to do such this is an indication that you have excessive carbon build-up in the lands and this won't allow the rings to properly seal during the combustion process. If you are unsure of the condition of the piston and cylinder I recommend getting a professional opinion from a local saw shop in your area. Good luck and let us know how you make out. As for the Golf brand parts, I've never heard of these so I can't speculate on their quality. Generally, though, aftermarket parts are inferior to those that are original equipment.

I pulled the cylinder and the scratches are bad.
There is a small depressed divit in the cylinder wall.
Well, it's toast.

I almost got a used 029 cylinder on ebay today...but i was outbid.

So I am on the lookout for a used cylinder. New is $207 from bailey's and locally $238. The saw retails for $359. Seems like unless I can get a used for cheap, may be getting a new saw is better ? Any ideas ?

Unless you can find the parts for a reasonable price, I think I'd go for a new or good used one. Often times, when there is that much damage, there are other parts that need attention too. For instance, what caused this in the first place? Unless it was run without oil in the gas, it could have been injesting dirt through a bad filter, or running too lean because of a crankcase leak, carb problems, or leaking seals. Also, when the cylinder got trashed, the metal went somewhere, and other parts probably got hot, so you may need to replace the crankshaft seals, and possibly the shaft and rod bearings. The crank is probably ok, but needs to be looked at too.

I would look at trading it in, the shop by me will take trades especially if it is a stihl saw and you are buying a new stihl chain saw...

my .02