Husqvarna 50 piston 44mm or 45mm???

[maclites]

My 1989 Husky 50 needs new piston. I've seen 44mm aftermarket pistons for sale on-line, but my specification manual gives bore as 45mm and displacement as 51cc. Piston part number from my parts list is 503 50 44-02. I've seen aftermarket husky 51 pistons listed as 45mm - will they fit my saw or do I have to go to Husqvarna for one? I've not found a cross-reference to my part number.

Thanks!

 

[Freakingstang]

Did you actually measure the piston?

I have messed with a ton of 50's, 51's and 55 ranchers.

All the regular 50's I have seen are 44mm. They made a 50 special that was basically a 51. It was a 45mm bore, but I don't remember what years they made them. I'm thinking they were older than 89, like mid to early 80's.

The 51 was, as far as I know, always a 45mm bore (51cc).

The 55 rancher was 46mm bore(53cc) for all years except 1997 or 98 (can't remember)

The pistons should interchange. I have put 51 (45mm) piston and cylinders on 55 and 50 bottoms ends. The bottom ends should be identical, so the 51 piston you are seeing on ebay should work. I could be wrong here, but the last time I checked the 51 piston was not available anymore through Husqvarna.

On a side note, why does it need a piston and not a cylinder or rings, or all of the above?


-Steve

 

[Farley9n]

For what it's worth....I used a Golf brand piston and ring in a buddy's 51 two weeks ago. It was cheap but so far has worked out just fine. it was a "Buy it Now" on ebay and I had it within 3 days. The old piston was toast and it took some time to get the bore cleaned up......Bob

 

[Grande Dog]

This might help.

 

[buck futter]

steve,

How did you ever make out hopping up the 51/55's?
Did you move on to bigger and better?

Buck

 

[Freakingstang]

steve,

How did you ever make out hopping up the 51/55's?
Did you move on to bigger and better?

Buck

I Still have a 51 and a 55, but it is hard to go back to the little ones after playing with the bigger, badder saws that give more rewarding gains. I will say the 51 seems to take mods better than the 55, from what little I have played with them.


Steve

 

[maclites]

Thanks to all for the info. Does anyone have specifics on what to do to warm this saw up a bit? I've done a good bit of automotive and small engine work and have access to machine shop. Is there a good book or magazine that details some of the things I've seen mentioned on this site (porting, exhaust mods, etc.?)

Freakingstang: Yup - 45 mm in my spec book and piston actually measures 44.8 mm with digital caliper. I'll be doing piston/ring/wristpin all at same time due to scoring. From what I've seen on this site I can likely clean up the cylinder. Thanks again!

 

[SawTroll]

.... The 51 was, as far as I know, always a 45mm bore (51cc).

The 55 rancher was 46mm bore(53cc) for all years except 1997 or 98 (can't remember)
-Steve

Good post again Steve!

I recently found a Husky spec sheet that listed the first EPA versions of the 51 and 55 as one size down in bore (to 44 and 45 repectively), making the 55 EPA a 51cc saw and the 51 EPA a 49cc saw. I think the sheet was dated 1998.

Edit; It is dated 1998. The non-EPA sheet from the same year show them with the normal 45 and 46 mm pistons, and 51 and 53cc.

 

[Freakingstang]

Thanks to all for the info. Does anyone have specifics on what to do to warm this saw up a bit? I've done a good bit of automotive and small engine work and have access to machine shop. Is there a good book or magazine that details some of the things I've seen mentioned on this site (porting, exhaust mods, etc.?)

Freakingstang: Yup - 45 mm in my spec book and piston actually measures 44.8 mm with digital caliper. I'll be doing piston/ring/wristpin all at same time due to scoring. From what I've seen on this site I can likely clean up the cylinder. Thanks again!

Muffler mods on both of mine made the biggest gains. The best gain I had was from a pair of 3/8" pipes welded on the muffler. I have pics in the double barrel shotgun muffler thead.

Is the cylinder a closed transfer or open transfer port? If it is closed, 1mm removed from the exhaust and .5mm from the intake will wake it up. You could also remove the material from the intake side of the piston instead of the intake port. I prefer porting, but some prefer the piston skirt removal. I used sealant instead of a gasket to raise the compression back up after taking the material off of the roof of the exhaust.

-Steve

 

[maclites]

Steve,

I saw the shotgun muffler. What is it that makes the difference - better flow or a little back pressure from the tubes? I've seen in some photos and at lumberjack shows some saws with really long tapered exhausts.

How do I tell open from closed port? I'll need a better description of just what to grind/mill out. As for sealant, is hi-temp (copper filled)RTV OK?

Thanks Again!

MC

 

[Freakingstang]

I think the length of the pipes combined with the size helps keep some backpressure. I tried one with a 3/4" ID pipe, and the gains weren't as great as the twin 3/8" (before they were drilled out). Got me there???? The 3/4" single pipe still made a big improvement over stock, but not optimised like the twin pipes were. The long pipes you see at lumberjack shows and races are expansion chambers. Thier purpose is to shove unburned fuel and air back into the cylinder after it fires for, lack of a better term, a supercharged effect. They make big power, but are not ideal for normal work use. It is the same concept on a dirt bike. Take the expansion pipe off and the power drops, significantly.

I'll try to post some pics up of an open and closed port. RTV is not a good choice for longevity. I use Loctite 518 or 515. They are anerobic (sp?) sealers, they don't harden and are good for constant use with gasoline. RTV isn't.

 

[maclites]

Steve,

Thanks for the additional info. I'll try to pick up a parts saw from local Husqvarna dealer so I have a muffler and other parts to fiddle with. I'll try to get some pics of my saw parts - if that would help. Both the intake and exhaust ports into the cylinder are a single hole. Does that help any?

I've talked to some of the guys at work who have tinkered with 2 cycle bikes, and they're talking about matching transfer ports, roughing up the intake, etc. Is there a good book or magazine out there for doing some of these mods? Will a motorcycle mod book be any help, or won't those things apply to saws?

Mark

 

[Dan Forsh]

Rather than start a new thread, I thought I'd jump in and ask those who have already contributed here. I need the part number for a piston for my 50 Rancher. Ideally if someone could fix me up with the IPL that would be even better.

Thanks,

Dan

 

[maclites]

Dan,

See post #4 in this thread for a .pdf file with part numbers for piston, rings, cylinder. What I've learned is that piston/bore diameters may vary depending on the age of the saw. My 1989 50 has a 45 mm bore. Once you find the diameter, there are several listings on Ebay for pistons. Check under Husqvarna 50, 51, & possibly 55 to see what the right size is listed under.

Mark

 

[SawTroll]

... I need the part number for a piston for my 50 Rancher. Ideally if someone could fix me up with the IPL that would be even better. ..

There are several IPLs for the Husky 50 on Huskys UK web-site.

Here is an exemple from 1984, and here is another one from 1989.
I took a quick look at several of them, and it looks like there was one part number for the complete piston from 1983 to -88, and another one after that.
My guess is that the change reflects a change from 44 to 45 mm, but I am not sure.

 

[Dan Forsh]

That's for the info gents.

Mine is the older Rancher version, the one with the white top cover in the first link on Sawtroll's post. Incidentally how do you access those IPL's Sawtroll? The weborder site asked me for a user name and password. I have a copy of Partscan which will still list out the documents, but I can't access them anymore, so I knew there were two IPLs for the 50.

The main thing I need to know is what's interchangeable. Once I know if I've got a 44 or 45 mm piston/cylinder I assume this will make things a little clearer?

I have an owners manual for the 50 Rancher from, I think, 1982, which quotes 44 mm.

 

[SawTroll]

... Incidentally how do you access those IPL's Sawtroll? ...

As I am a Norwegian, I start here, then select "Worldwide" down in the right corner.
Then I select "United Kingdom", and "Search & Download Manuals" from the row high on the page.
Finally I enter the numbers in the model designation ("50" in this case) in the I... P.... L... search window.
I then get a long list of products containing 50 in their model designation, and scroll down until I find what I want. In this case I think I found seven or so different IPLs for model 50 chain saws.

If you just enter "chain saw" in the search window, you get a list of all the chain saw IPLs in the library to choose from. The library goes back to the early 1970s. :greenchainsaw:

 

[maclites]

Pics of cylinder from my husky 50. What is difference between open port and closed port? Do the pics show the difference?

Have cleaned up cylinder and have new piston/ring/wristpin ready to put back together. Do I reassemble piston back onto the connecting rod with connecting rod still attached to the crank which is still in the case, then put cylinder back on? I kind of remember seeing posts where a hose clamp can be used as a ring compressor. Any tips here would be appreciated.

Thanks!
Mark

 

[GAPULPER]

You have open transfer ports which is visible in the third picture looking into the bottom of the cylinder. Open indicates that the full length of the transfer port is open to the cylinder as compared to a closed port has the bottom and top open with the center or middle section closed to the piston / cylinder.
Yes, you reattach the piston to the small end of the connecting rod with the exhaust side facing the front or exhaust port and then slip the cylinder down over the ring. You should be able to compress the ring with your fingers and work the cylinder down onto the piston carefully without any special tools.

 

[Dan Forsh]

Like the man said, your piston only has one ring, so it should be easy to do with just fingers. It gets more difficult when you are trying to keep two rings in place in different positions.