There's not a big difference in the maximum chain speed between a 6T-3/8LP and a 7T-.325 sprocket -- between 3 and 4% if you pretend that torque...
Yeah, there are or have been a bunch of these on the market that probably all come from the same factory -- including the Northern Industrial and...
Assuming "blown" means scored, you can usually get away with cleaning up the cylinders and replacing the piston. There are aftermarket pistons...
Holy cow. Fresh gas, and THE 610 RUNS! Also pulled the muffler on the 920, and it's not scored. Now I have to figure out what's locking it up.