My Dad's old 1987 model 50 husqvarna finally refused to start after over 20+ years of firewood cutting. I told him I would look at it and see if I could get it back into service. Pulled the muffler and the piston and and ring are heavily scoured. I believe the stock piston and cylinder are 44mm. There are plenty of 45mm and 46mm top ends out there on the net. Does anyone know if there would be any problems simply stepping up to the bigger piston and bolting up the 46mm cylinder (originaly for the 55 rancher). Looks like a simple big bore upgrade but the current carburator is the Walbro WA 82A. Would the carb. need an upgrade as well?
Husqvarna 50 big-bore upgrade question
- Thread starter Axlerod74
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All you will need is the larger piston and cylinder, everything else will swap over and work fine. Check out site sponsor Bailey's for a good deal on a aftermarket 46mm top end. Bailey's - NWP Cylinder Assembly for Husqvarna 50, 51, 55
wigglesworth
Booned
Do yourself a favor, and replace the intake boot, impulse grommet and the fuel line, if not, you will most likely be replacing the P&C again......
Let us know how and if that works out. I had believed that a 55 jug would only fit on cetain later 50's or 50 specials.
But I really got confused over the whole thing.
I was also concerned about the same thing. I saw a listing on e-bay for a 46mm top end (53 cc) and it listed all of the model saws it would fit. Under the model 50s, it only listed the ones for 1989 and later as well as the 50 specials. Mine is a 1987 model but the bulkhead and intake boot looks the same.
Thanks for the link! I buy quite a bit from Baileys but I did not realize NWP was making this top end. And it is a little cheaper than the best price I have seen on e-bay. Looks like the impulse grommet and intake boot are the same for the older 50s and newer 55s. I think the kit will match up. Any thoughts on wether the older carb. will be sufficient to power the 53cc upgrade?
Now that you mention it I did run into a small issue when installing a "big bore" on a older model 50. I do not know the technical names for these parts and areas of the saw, so please bear with me. On the bottom of the cylinder there are "lips" that drop inside the top of the crankcase. The "lips" on the larger cc cylinder were thicker and would not fit inside the crankcase opening. I used a dremel, with a sanding drum, and it only took me a couple minutes to thin those "lips" down and everything went right together. The saw now has hundreds of hours on it with no issues.
Yoopermike
ArboristSite Guru
Ive heard of that before.. I was curious to try it but. I already have a 51 and 55 in the arsenal. I will leave my 50's be 50's .
I just hit the order button and placed an order with Baileys for the "big bore kit".....then read your post. I was thinking if there was any difference it might be the lower cranckcase opening. If you have had good luck with this method, I will try it. Seems simple enough to modify and I bought a new cylinder gasket to get a good seal. Did your kit come drilled and tapped for de-comp? Dad is in his early sixtys and has a lot of pain in his elbow. He might like the de-comp.
That follows what I was thinking as per this Husqvarna service notice.
MechanicMatt
Cut Split Stack Burn
i too am in the midst of rebuilding a 50. keep us all informed how it works out, my 50 is a 83, a bit older but she is a good looker.
I actually installed a used OEM 45mm model 51 top end, so I can not say if the aftermarket one has a decomp. I looked in the FAQ on the Baileys parts and it seem it does have a decomp, along with a plug in case you do not want to use it. From what Baileys is telling me this Aftermarket kits is made in such a way that it should fit any 50-55 model Husqvarna saw, like a universal mount.
Thanks for the research Mark. I will take some measurements when I pull the head off and compare to your file. The kit description on Baileys indicated it would fit the model 50 but that may not take into account the older models before the service notice.
This kit has a 46mm top end but I believe the tabs going into the crankcase would have the same outside diameter. Judging by the service notice modifiedmake sent, looks like I might have to grind off about 2mm (at least on the OEM kits). Do you recall if you had to grind that much off your project? Thanks for the info.
vw_motorsports
ArboristSite Guru
I had a 50 and put a 55 cylinder on it ran nice. The other thing I would upgrade to is the complete carb and top cover from a 51/55. Much better choke setup than the 50 setup...and essentially you'll have a 55 at this point. If the bigger jug's skirts fits inside the case...the other thing is the 50 does not have the cast bosses for the air injection, well my 50 didn't have them. The impluse grommet you can use some silicone vacuum hose from the automotive side.
This 50 does not have air injection however it is only lacking the cast bosses and air horn. The bulkhead does not have the hole for the horn to pass through either. I definately like the choke better on the 55s. Right now I don't have the spare parts for the complete 55 conversion. If I can get Dad back to cutting firewood, I think he will be happy. I loaned him my 55 while I was working on the 50 and he loves it...................I may not get it back!
I pulled the 44mm cylinder off and compaired it to an old 46mm (from a 55 husqvarna) that I had. The 46mm is noticably larger at the bottom. If the one from Baileys is the same size, it will certainly take some modifying.
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Is your 50 older (pre 91)? Any crankcase issues?
What year was your 50 produced?
