Husqvarna 50

[Bus Driver]

My first post on this forum. Have lurked here and read about the Huskys for some time. Enjoyable.
I get long winded, please be patient with me. Some forums where I offer advice have seekers who offer too little information to explain their problem.
My Husqvarna 50 is (was!) one of the 5 operational saws I have.
Serial 9140681, purchased new 06/01/1989 for $319.00-- the newest saw I have that was purchased new by me. Never a major repair until this week. Ran out of gas and would not run again unless fuel is dripped into the carburetor intake. Fuel line OK, but it is the original line. Suction on the carburetor end of the fuel line pulls fuel up just fine.
Local independent shop said compression seemed low and looking in the exhaust port, piston ring (there is just one) is cracked. Further disassembly is not yet done. Not sure what parts may be required to restore this (has been) excellent saw.
It has always leaked bar oil, but other good qualities more than offset that shortcoming. Just like my wife, I appreciate her for what she is rather than despising her for what she is not.
My parts list has 1988 prominently on the front. Cylinder complete is 502 11 60-01, piston complete is 505 34 13-07. Apparently these particular parts were used for relatively few saws and the parts changed sometime in 1989. If new piston and cylinder are needed, looks as if only genuine Husky parts for those numbers are available and the price for those is far more than I would spend on this saw.
Not yet sure of the piston diameter-- does anyone here have that information? 44mm? 45MM?
Other threads on this forum discuss parts swaps for the 50, 51 and 55. One fellow, not here as far as I know, claiming long experience informs me by email that parts swap of cylinder and piston will not work on my saw due to the crankshaft being different! Admittedly, the crank number is different, 503 11 21-01 and apparently used for short time period. But the piston pin bearing is the same as the other 50, 51 and 55. So I do not understand how the crank is the problem unless the stroke is different, and I doubt that is the case.
The gasket between the cylinder and crankcase is 503 16 21-03, which seems to be the same for all of the 50, 52 and 55.
Your help is requested. Will answer your questions to the best of my ability.

 

[Hermann]

Try search for more info, but I do have experience here with a Rancher 50 same issue no compression scored piston, bought a cylinder piston kit, but the piston would not fit due to the crankcase opening being too small. Some have said they actually ground down the crankcase to give an extra mm clearance. Mine was the 44mm piston, saw was bought in the late 80s - I inherited it from my family - Dad's then Brother n law then me..

Apparently some Husky 50s latest models did have a 45mm opening that allowed the 45mm piston.

Measure your piston, if it's 45mm than you can use cheap piston/cylinder repair kits for sure, or perhaps someone can tell by your serial number or manufacture date as to what one you have.

If your cylinder is still good then there is a 44mm piston, but forget the name, I might try that, but ended up buying a new saw, then another..

 

[thomas41]

Hope this will help

http://www.arboristsite.com/chainsaw/199985.htm

 

[MechanicMatt]

I too have a early white top, I ground the cylinder a hair on each side to make it work. Couldn't imagine grinding my case. Just put it in a box and ship to me, ill give it a warm home

 

[Bus Driver]

With the generous assistance of one of the regulars here, I find that my saw was made in the second quarter of 1989, raising in my mind the (hope and) possibility (probably remote) that the 1988 parts list might not be for this specific saw. Will the part number be on the piston and on the cylinder? And are they likely to be legible after all this time? That will be as definitive as it gets.

 

[SawTroll]

With the generous assistance of one of the regulars here, I find that my saw was made in the second quarter of 1989, raising in my mind the (hope and) possibility (probably remote) that the 1988 parts list might not be for this specific saw. Will the part number be on the piston and on the cylinder? And are they likely to be legible after all this time? That will be as definitive as it gets.

Your saw dates to week 14 1989. The topend was changed to the 45mm one feve weeks later, from serial number 9190006.

At least that is what a Husky service bulletin from 1989 tells.

 

[Bus Driver]

"The topend was changed to the 45mm a few weeks later" Very interesting and very helpful. Does it indicate if the crankshaft and/or the crankcase remained the same? Since the piston pin is definitely the same, and probably the stroke remained the same (the piston diameter change alone accounts for the displacement change), if the crankcase is the same, the 45mm cylinder should bolt right on.
But it might have been changed when the cylinder and piston were changed. Even little bits of information may prove helpful. Thanks for your efforts.

 

[Bus Driver]

Perhaps this is the bulletin SawTroll found. PDF

http://www.google.com/url?sa=t&rct=...uIGQBg&usg=AFQjCNGpfEcMbudpjleDAfR7OPHVcXU1vw

It refers to the "50 Rancher". Mine is simply "50", not sure what differences the Rancher may have. And after the changes of May 1989, it became the "50 Special". The term "excluded" means the previous part number, also called obsolete. One of the piston assemblies apparently was for France only.
The gasket between the cylinder and crankcase remained unchanged as did all the other engine parts.
The "50" and the "50 Rancher" look different in the area of the pull rope starter and the top cover looks to be different. Is one supposedly more powerful than the other? Anyone know why the different models?

 

[SawTroll]

Perhaps this is the bulletin SawTroll found. PDF

http://www.google.com/url?sa=t&rct=...uIGQBg&usg=AFQjCNGpfEcMbudpjleDAfR7OPHVcXU1vw

It refers to the "50 Rancher". Mine is simply "50", not sure what differences the Rancher may have. And after the changes of May 1989, it became the "50 Special". The term "excluded" means the previous part number, also called obsolete. One of the piston assemblies apparently was for France only.
The gasket between the cylinder and crankcase remained unchanged as did all the other engine parts.
The "50" and the "50 Rancher" look different in the area of the pull rope starter and the top cover looks to be different. Is one supposedly more powerful than the other? Anyone know why the different models?

It is not the same document (sorry, can't post mine, as it is a paper copy). The one I refer to mainly focus on slight changes in cylinder bolt diameter and corresponding changes in the case, besides the top end itself.

The Rancher disignation on the 50 had vaned away trough the 1980s, so it is slightly surpricing that they used it in those documents. The saws that originally came with the 45mm top end should be marked 50 Special though, not just 50.

 

[Bus Driver]

Does anyone have a crankcase that is from a 51 or 55 Husky? If so, the measurement of the diameter of the piston/rod hole there would indicate what the factory considers to be proper clearance for the 45 mm piston. That measurement, in mm or in decimal inches, would help me to know if my saw is likely to accept the 45mm piston without modifications. Your help is appreciated.
As best I can determine, the stroke on all 50, 51 and 55 is 32mm.

 

[MechanicMatt]

So you need the in diameter of the small end of the rod? I have a closed port 55 top end riding on my 1982 50 rancher, I did have to use a dremel to grind away to make it fit, but she fits. Tomorrow if I remember Ill measure the rod on the old 55 I have laying on the parts pile.

 

[Roanoker494]

In my experience the 45mm and 46mm top ends are direct bolt on replacements for any Husqvarna 50, 51 or 55 built after 1987. Saws built in 1987, and back, will require the use of the correct 44mm top end or minor modification can be made so that the larger top ends will fit. There are no differences in the crankshaft diameters no matter what year it was built.

 

[Bus Driver]

The rod issue is settled in my mind. The lower skirt of the piston must travel into the crankcase at the bottom of the stroke. And the fuel-air mixture must at the same time travel up around the piston in the area between the piston skirt and the crankcase. Whatever is necessary to get that hole in the top of the crankcase the proper size is what will be done. The desired information is the size of that hole on the Models 51 and 55.

 

[PowerMax]

I was able to bolt a new 46mm piston/cylinder onto my Husky 50 with no issues. However, the serial number shows it was made in week 21 of 1989.

 

[Roanoker494]

The rod issue is settled in my mind. The lower skirt of the piston must travel into the crankcase at the bottom of the stroke. And the fuel-air mixture must at the same time travel up around the piston in the area between the piston skirt and the crankcase. Whatever is necessary to get that hole in the top of the crankcase the proper size is what will be done. The desired information is the size of that hole on the Models 51 and 55.

With your saw being built in 1989 it will have the larger opening like the 51 and 55 all ready. The area of the crankcase that is smaller on the older saws is where the "lips" on the cylinder go into the case. The easiest option I have found is to alter the cylinder "lips" and leave the case alone, no use in dumping handfuls of metal shavings into the main bearings.

I do not have a 51/55 case here right now but there should be one here in a couple days and I will try to get some measurements.