I just finished up work on a Husqvarna 55 Open Port. It came to me with a china cylinder and piston and when I measured squish, it was bigger than 0.062" solder. I think it was probably 70 or 80 thou. The saw could be stalled easily with the 20" 3/8 (regular) that it came with. I decided to try to get it closer to Husky specs and brought squish down to 0.020", widened the exhaust 0.040" on each side. I gave it a little more intake (78 degrees) by removing about 0.040" off the intake side of the piston skirt (matched the intake port). I beveled the piston slightly at the exhaust to get (104) and raised the transfers up. That was the one area I missed slightly. I was going for 122 transfer and ended up at 118 or 119.
The end result is a saw that I can't stop unless I really muscle it while dogged in. It's so much better than how it came. I decided to muffler mod it also (gutted the baffles inside) which improved it even a hair more and advanced the timing 5 or 6 degrees. I'm not sure I noticed much difference on spark timing. Need to tweak a little more back and forth. I'm thinking the biggest difference was sqish and getting the port timing more normal.
That got me to wondering, can I throw LP 3/8" chain on it and go to a bigger bar size for the occasional bigger work? 20" regular 3/8 0.050" is no problem for this saw. I figure I can go a little bigger with the Low Pro. Am I thinking correctly or would this just break something? Lets assume the bar and sprocket are rigged to work with the LP.
The end result is a saw that I can't stop unless I really muscle it while dogged in. It's so much better than how it came. I decided to muffler mod it also (gutted the baffles inside) which improved it even a hair more and advanced the timing 5 or 6 degrees. I'm not sure I noticed much difference on spark timing. Need to tweak a little more back and forth. I'm thinking the biggest difference was sqish and getting the port timing more normal.
That got me to wondering, can I throw LP 3/8" chain on it and go to a bigger bar size for the occasional bigger work? 20" regular 3/8 0.050" is no problem for this saw. I figure I can go a little bigger with the Low Pro. Am I thinking correctly or would this just break something? Lets assume the bar and sprocket are rigged to work with the LP.
