Hi Folks.
I bought a 2nd hand Stihl 039 about 12 months ago. It had not done a huge amount of work but had not been loved.
When I got it the entire thing was a ball of metal, sawdust and oil under the plastic covers.
I stripped it and cleaned it and put it back together. Modded the muffler, tuned it up, bolted on a new bar and chain and off it went.
It has run fairly well but not as good as I feel it should no mater what I do.
I have recently stripped the carb and put a kit through it, which it needed as it was full of crap and the seals were hard.
I hadn't ventured into the motor as yet and decided to have a better look.
I removed the muffler and shone a torch in. The top of the piston had a thick layer of black goop on it. I have used the same mix of 40:1 fully synthetic oil in 98 octane ethanol free fuel in this and my 066 and the 066 is spotless inside. Shiny silver top on the piston.
I figure it is carbon deposited by the previous owner.
So I popped the jug off and found a 2mm thick layer of black goop burnt onto the top of the piston and even more lining the top of the cylinder head around the spark plug.
I also found the motor itself has a nice layer of green 2 stroke oil in it, the same as the 066 so my mix is ok.
Inspection of the piston showed more wear on one side than the other and I found the bottom ring siezed tight on one side of the piston. Once I tapped it out I found thick layers of dry black carbon under the rings, like patched of dry tar.
The inside of the jug cleaned up nice with a quirt of bore tech rifle barrel carbon remover. It actually looks really nice with no uneven wear or marks. There was also a 2 mm thick layer of carbon lining the exhaust port.
I have ordered a new piston, rings, seals, bearings, hoses etc etc and will be giving it a full birthday
I will take some pics of the gunk under the piston rings tomorrow and post em up.
Does anyone have any advice or tips on rebuilding the motor. I am no small engine mechanic but am a tradie and very mechanically inclined.
Cheers
I bought a 2nd hand Stihl 039 about 12 months ago. It had not done a huge amount of work but had not been loved.
When I got it the entire thing was a ball of metal, sawdust and oil under the plastic covers.
I stripped it and cleaned it and put it back together. Modded the muffler, tuned it up, bolted on a new bar and chain and off it went.
It has run fairly well but not as good as I feel it should no mater what I do.
I have recently stripped the carb and put a kit through it, which it needed as it was full of crap and the seals were hard.
I hadn't ventured into the motor as yet and decided to have a better look.
I removed the muffler and shone a torch in. The top of the piston had a thick layer of black goop on it. I have used the same mix of 40:1 fully synthetic oil in 98 octane ethanol free fuel in this and my 066 and the 066 is spotless inside. Shiny silver top on the piston.
I figure it is carbon deposited by the previous owner.
So I popped the jug off and found a 2mm thick layer of black goop burnt onto the top of the piston and even more lining the top of the cylinder head around the spark plug.
I also found the motor itself has a nice layer of green 2 stroke oil in it, the same as the 066 so my mix is ok.
Inspection of the piston showed more wear on one side than the other and I found the bottom ring siezed tight on one side of the piston. Once I tapped it out I found thick layers of dry black carbon under the rings, like patched of dry tar.
The inside of the jug cleaned up nice with a quirt of bore tech rifle barrel carbon remover. It actually looks really nice with no uneven wear or marks. There was also a 2 mm thick layer of carbon lining the exhaust port.
I have ordered a new piston, rings, seals, bearings, hoses etc etc and will be giving it a full birthday
I will take some pics of the gunk under the piston rings tomorrow and post em up.
Does anyone have any advice or tips on rebuilding the motor. I am no small engine mechanic but am a tradie and very mechanically inclined.
Cheers