Ran a retired logging 2012 660 Magnum on my machine today.
I didn’t have the dyno at the time when I got the saw. I would’ve tested the saw before I did any work to it.
This saw was almost all in pieces in the logger’s parts box. Just the crank case with the cylinder still on.
They went to 661’s so the 660’s were not needed anymore. So I got the parts for free and assembled the saw back together with parts that were in the box. There was a hacked dual port muffler in the box too
I purchased bolts, clutch, rim, starter dogs, from a buddy that runs a small engine shop.
I noticed by spinning the flywheel, the compression feels low. Inspecting the exhaust port, I find the rings seems to be sticking. (These loggers use TC-W3 two stroke oil, shame on them)
Pulled cylinder, used the rings themselves to clean the grooves out, smeared Yamalube oil on the piston, put the cylinder back on.
Feels much better for compression.
My logging buddy pulled the rope, said saw feels like normal compression, the way it should be.
After several sheared flywheel keys, cleaning up the flywheel taper and crank taper, the flywheel finally stayed in place to run on the machine.
The saw made 5.2 hp at 9,000 rpms.