Chainsaw Repair

OK since I have  not ran or worked on a 55 help me know more about them.

Here is what I have in memory (right or wrong).  There was 55 and 55 rancher, what was the difference?
 I have heard of open and closed port 55 saws.
What was the bore and stroke?  53cc or what cc?

53cc open port is the type 2 replacements for the poulan 325 53cc 46mm saws. I bet they are the husky 55 top ends. My poulan 325 is type 1 closed port 46mm like the 5000 plus cylinder with a piston that looks like the 026 piston with windows.

The other 55's are closed port, 51cc? 45mm piston.

I wonder with it being 45mm closed port if it was the jonsered 590 top ends.

New guy here and I can help shed a little light on the closed port discussion. The closed port top ends were available 1998-2000 on the Husqvarna 55's that were marked with only "air injection", none of the Ranchers came with it. The closed port top ends are still available new as part number 503 97 18-71 but they run in the neighborhood of $200-$250, which I guess is not to bad for a new OEM top end. I do know that the Jonsered 590 top end is a direct bolt on for the Husqvarna 50/51/55 chainsaws but I can not say if they had the same part numbers. There was one of the saws that had a 44mm closed port bore that is claimed to be the best of them all because of the combustion chamber design, I believe it was from the Jonsered 490. There are several other bolt on options for this series saw as well, some are open port and some are closed port.

I have also heard the story about the older 50's having a different cylinder bolt pattern, though I have never seen it myself and I have messed with them as old as 1983. The only issue I have ever ran into is the opening in the case is slightly smaller in the 50's made prior to 1987, though the service bulletin states that the the change date was 1989. I was able to install a 46mm top end on a 87 model with no modifications but I had to do some grinding on a 85 model. This issue can be quickly overcome with 15-20 minutes work with a dremel tool, you have to either make the opening larger or the "cylinder lips" thinner.

For the folks that have never seen the internal differences between the closed and open port cylinders. These pictures are from a model 51 that I installed a closed port cylinder on.


Open Port piston, "full circle" style

Closed port piston, factory windowed

There is a way to tell the cylinders apart from the outside as well. Look at the cylinder fins down the right side. The closed port is only missing the bottom three fins where the open port is missing all but the top three. 

Welcome and Thanks for sharing your info.

The closed port piston looks like the jonsered 590 piston I had. The cylinder closed port one looks like others I have seen posted for a 590. But if you look at my closed port jred 590 cylinder it was different in thread of 590. So maybe somewhere along the line they changed where they all wore the same.

Just like the replacement cylinder for poulan 325 type 2 is the husky 55 open port 46mm.