Worked on my Jonsered 49SP today. It started out by truing the bar. Then I thought....I should pull the muffler and see what the piston looks like. Well there is/are some scoring. The muffler port was all carboned up. So, I started scrapping and carbon got everywhere...so, I took the air hose and blew it out...not thinking about the intake ports being open to the crankcase which got the bits of carbon in it. Now...I need to get that out of there...so apart came the saw.
The ring was partly stuck to the piston. Piston is scored and the ring grove closed up a bit because of this. I spent some time getting the carbon off of the piston in the wristpin area(wristpin would stick on the carbon build up in the hole in the piston), ring grove, and the top. Now the ring is free to expand and contract withing the groove. Ring contact with the cylinder is a plus. I probably will replace the piston and ring some time in the feature.
I flushed the crankcase twice with mixed gas. I'm glad I did because the gunk in the crankcase turned turned the gas black both times.
On reassembly I took some 2 stroke oil on the crank bearings, piston, ring, and wristpin.
I didn't do a compression check before I did the work because I wasn't planning on taring the saw down. I should give it a check after a few tanks of mix.
I think it has more power.. it starts better and after a carb adjustment I think it idles better.
This is probably better than the mod I mention in this thread:
Did a power mod on my Jonsered 49sp!
Thanks for taking a peek!