Husqvarna 55 new top end?

[nmorton]

Other than a few cc's how much difference is there between the 55 and the 51? I have a 1999 model 51 and use the poo out of it (firewood guy, not daily use).

Was/is there an open port / closed port option and how would I know w/o tearing it down? It runs good still but pulls over a lot easier than when it was new.

Thanks,
Jeff

The 51 has 45mm bore, 51cc for 3.1hp. The 55 has 46mm bore, 53cc for 3.4hp. Weight, idle speed, and max rpm are the same. (According to my owners manuals) I believe all parts are interchangeable. A 55 cylinder will bolt straight onto a 51. Just did this with my old 51, now i have two 55s. Not to sure about the closed ports. I don't think they made a closed port 51, but i'm not sure. Have heard the closed port 55 have a 44 or 45 mm bore, cylinders have +++++++++ stamped on them above the flywheel, and something about the cooling fins are different,but don't know for sure. There are several threads about this on this site.
Sounds like yours has lost some compression. Before i rebuilt mine, you could pull it over easy with only two fingers. Finally broke down an put a 55 cylinder/piston in it. Wow BIG time difference. Better not try starting it with two fingers now. OUCH!!!
For the money they are very good saws IMO. I run mine with 16" bars for limbing and climbing. You can find replacement parts most everywhere.:msp_thumbsup:

 

[jh35]

The 51 has 45mm bore, 51cc for 3.1hp. The 55 has 46mm bore, 53cc for 3.4hp. Weight, idle speed, and max rpm are the same. (According to my owners manuals) I believe all parts are interchangeable. A 55 cylinder will bolt straight onto a 51. Just did this with my old 51, now i have two 55s. Not to sure about the closed ports. I don't think they made a closed port 51, but i'm not sure. Have heard the closed port 55 have a 44 or 45 mm bore, cylinders have +++++++++ stamped on them above the flywheel, and something about the cooling fins are different,but don't know for sure. There are several threads about this on this site.
Sounds like yours has lost some compression. Before i rebuilt mine, you could pull it over easy with only two fingers. Finally broke down an put a 55 cylinder/piston in it. Wow BIG time difference. Better not try starting it with two fingers now. OUCH!!!
For the money they are very good saws IMO. I run mine with 16" bars for limbing and climbing. You can find replacement parts most everywhere.:msp_thumbsup:

Hey thanks! It doesn't pull two fingers easy yet but a noticeable difference. I run a 16 inch .325 setup. I don't have CAD but all the reading I do on here makes me want to try a 372.

My local very small but very good dealer has (2) 55's and a 51 that are all getting new 55 P&C's and will be for sale shortly. If I buy another saw it will be bigger and now if I need a rebuild I want try it myself. (Dang AS anyway)

 

[nmorton]

Hey thanks! It doesn't pull two fingers easy yet but a noticeable difference. I run a 16 inch .325 setup. I don't have CAD but all the reading I do on here makes me want to try a 372.

My local very small but very good dealer has (2) 55's and a 51 that are all getting new 55 P&C's and will be for sale shortly. If I buy another saw it will be bigger and now if I need a rebuild I want try it myself. (Dang AS anyway)

I used my 51 for a couple years with the low compression. It still started, idled, and ran great, just low on power. I don't own one, but have used several 372s and they are strong. I have the 51,a 55, Husky 261 ,262xp, a 257 i'm converting to a 262, and a 365. I've been eyeballing that 562xp. Still trying to get up the nerve to ask the wife about the possibilities of getting one. She just don't understand why i NEED 10 chainsaws and i'm not a even a professional logger!!! Huh, go figure...This is a GREAT site, but dang it gets ADDICTIVE!!!! :crazy1::crazy1::crazy1::crazy1:

 

[Roanoker494]

Just saw a oem closed port cylinder/piston for 55 listed on ebay today. First one i have ever seen. Buy it now for 250.00.
If i knew how i would post a link to it.

That particular top is for sale but not really for sale, I know cause I am the seller........... I would much rather just keep it but if someone was willing to pay the asking price I would be willing to let it go. The 45mm closed port was originally found on the 55 EPA built from 1998-2000. There was also a 45mm closed port top end installed on the Jonsered 590 that is a direct bolt on, the 590 top end did not have a decomp port and the 55 did. That was also a 44mm closed port found on the Jonsered 490 that is a direct bolt on, I have one installed on my 1990 Husqvarna 50 Special and a spare on the parts shelf.

Roanoker on here is a huge fan of the 55 Husky

Guilty as charged, got a 55 Rancher on the way from NC right now. Sadly enough I missed out on another 55 this morning from right here in my home state........ I went into the auction page, read the description and hit buy it now for $60 but it came up as no longer available....... Someone else had swooped in while I was reading the auction and pulled it right out from under me.

Other than a few cc's how much difference is there between the 55 and the 51? I have a 1999 model 51 and use the poo out of it (firewood guy, not daily use).

Was/is there an open port / closed port option and how would I know w/o tearing it down? It runs good still but pulls over a lot easier than when it was new.

Thanks,
Jeff

To run a open port 51 and a open port 55 side by side you would be hard pressed to really tell much of a difference. Now you can tell a difference between the closed port and open port, the CP will hold higher RPM's while in the cut. The CP also responds very well to simple muffler mods while the OP will not gain as much.

The CP 55EPA cylinder can be identified on the outside by the cylinder fins around the air injection pipe. The OP has three full fins at the top and all others are cut away, the CP has only the bottom three fins cut away. If you can see the numbers stamped on the lower lip all the CP's are stamped 44ZN15, no matter what bore diameter.

 

[bucknfeller]

That particular top is for sale but not really for sale, I know cause I am the seller........... I would much rather just keep it but if someone was willing to pay the asking price I would be willing to let it go. The 45mm closed port was originally found on the 55 EPA built from 1998-2000. There was also a 45mm closed port top end installed on the Jonsered 590 that is a direct bolt on, the 590 top end did not have a decomp port and the 55 did. That was also a 44mm closed port found on the Jonsered 490 that is a direct bolt on, I have one installed on my 1990 Husqvarna 50 Special and a spare on the parts shelf.



Guilty as charged, got a 55 Rancher on the way from NC right now. Sadly enough I missed out on another 55 this morning from right here in my home state........ I went into the auction page, read the description and hit buy it now for $60 but it came up as no longer available....... Someone else had swooped in while I was reading the auction and pulled it right out from under me.



To run a open port 51 and a open port 55 side by side you would be hard pressed to really tell much of a difference. Now you can tell a difference between the closed port and open port, the CP will hold higher RPM's while in the cut. The CP also responds very well to simple muffler mods while the OP will not gain as much.

The CP 55EPA cylinder can be identified on the outside by the cylinder fins around the air injection pipe. The OP has three full fins at the top and all others are cut away, the CP has only the bottom three fins cut away. If you can see the numbers stamped on the lower lip all the CP's are stamped 44ZN15, no matter what bore diameter.

You posess a wealth of knowledge my friend

I have a 55CP cylinder here that is stamped 44ZN15, I thought they were a 44mm cylinder?

BTW, the saw I pulled the jug off was made in 2001

 

[Roanoker494]

You posess a wealth of knowledge my friend

I have a 55CP cylinder here that is stamped 44ZN15, I thought they were a 44mm cylinder?

BTW, the saw I pulled the jug off was made in 2001

Knowledge on the Husqvarna 50, 51 and 55....... Yes
About anything else? Ehh........ I can feed ya a line of bull and sound convincing.

The 44ZN15 stamp kept me confused for a while also and I still don't understand it but I have instead just accepted it........ If it has a decomp port it will be a 45mm 55epa. The only way I know to tell a 44mm from a 45mm Jonsered is to measure the bore. Also forgot to mention the CP 46mm Poulan 325 earlier, though I have never really researched that particular option.

I have heard of folks finding CP cylinders on 2001 models but I have seen many more OP cylinders in 2001. I have always figured Husqvarna used up what they had laying around and then changed to the OP later in the year.

 

[kmcinms]

Great 55 info again

And Roanoaker comes through once again. I've been running my 51 since '97. Still on the original sparkplug. Runs like new, still strong. All stock, no mods. Used it yesterday and today.
Dropped an 85 ft. pine today. 16" b/c 90-95% of the time, 20" b/c 5-10%. Favorite saw. Was bought for $140 in like new condition, 1 year old.
I might squirrel away a top end for it, just in case. :msp_thumbup:

 

[Metals406]

My first new saw bought from a dealer was a 55. . . It blew up years ago (my fault). I have the new Meteor kit for it, so it'll be getting resurrected.