Need some help with the rebuild of a Rancher 50 Whitetop

[Teotwawki]

Hi guys!

New to the forum, and figured I start my first post off with a Husky rebuild. The saw was bought new by my dad back in 83 or thereabouts and had served the family well for almost thirty years without a single repair. However, about a month ago we were working in the bush and was acting like it blew up.

Tore it down last night and this is what I managed to find...

View attachment 237251View attachment 237252View attachment 237253View attachment 237254View attachment 237255

Don't pay too much attention to the green looking (flash effect I guess) debris in the cylinder, they're actually fibers from the yellow rope I used as a piston stop. Anyhow, the scoring isn't too severe, but it definitely needs a piston. The cylinder actually feels smooth to the touch so I think it's salvageable. What do you think?

Not sure why it let go, but I think it had been breathing dust and dirt from a poor fitting air filter that was likely very old.

I've never rebuilt a saw before and have minimal experience with working on small engines so I have a few questions...

1. Does the cylinder look ok?
2. Should the cylinder be honed? I've heard this is bad as there isn't much coating to begin with
3. Having trouble finding a piston. I guess husky doesn't make many parts for this anymore. Measures out to 44mm, and the parts diagram originally calls for piston kit 505341307, which I found out was replaced by 503457701. All I can find are these... not sure if they're right
Poulan ASSY PISTON 503457701
https://www.partstree.com/parts/?pn=505341307+
https://www.baileysonline.com/itemdetail.asp?item=EHP+503457701&catID=
4. Since I'm going for a full rebuild, I want to redo the carb, all the rubbers, seals etc. I've torn it down to the case, but have no idea how to split the crankcase. Is there any easy way to do this? Do I need a special tool?
5. The saw leaks bar oil like no tomorrow when it's sitting, but pumps okay when running. I can't see any cracks in the case, so I guess it must be coming from the oil pump. The shaft has some play back and forth, should it be replaced? Where else can it be leaking from?
6. One of the bar mount studs is stripped and needs to be replaced. Can't find any, any ideas where to get them? Are all husky studs pretty much the same?

I look forward to hearing your thoughts! Thanks guys,

J

 

[Teotwawki]

I don't think I embedded the pics right... gonna try again lol

 

[Teotwawki]

Gotta ask, why does the moderator have to approve every message? I keep getting this and can't find info on it, nothing in the FAQ's, is it because I'm new? Does it go away after a certain number of posts?

 

[SawTroll]

I believe they started monitoring the first 5 posts a while ago, because of all the Chinese scammers that tried to advertise their products by signing up here.

 

[SawTroll]

I am no expert, but it looks like the cylinder can be saved by using some mauric(?) acid to clean away the alu deposits from the piston - but first you have to determin the reason that this happened, as it isn't just normal wear.

There are several 44mm Husky/Jonsered/Partner/Poulan Pro pistons that will likely fit, but again I am no expert on those saws.

I basically just "bumped" your thread up, as many on here will be able to give you better answers, when they see it.

 

[A100HVA]

http://www.husqvarnaretailer.com/ddoc/HUSB/HUSB1990_USen/HUSB1990_USen_B9000024_.pdf

try this for starters.
yours needs piston,don't hone cylinder.
post serial number

 

[SkippyKtm]

First you'll have to figure out why had the failure, looks like a lean condition or possible carbon scoring on the exhaust side. It could be a bad fuel line, carb problem, air leak, etc.
Muriatic acid and sandpaper will clean it up, here's a video:
LINK



Do a search on "scoring causes" you'll find all kinds of related stuff...
Good luck!

 

[Teotwawki]

Hey guys,

Thanks for all your responses. Getting close to placing an order for parts. Based on some research, looks like lean seizure. All the rubber stuff is almost thirty years old, so that was likely it.

A100HVA, the serial is 5032843... what year do you think it is?

Skippy, thanks for the link. Muriatic acid is kinda scary, but I guess I'll give it a shot. Do you think sandpaper alone would clean that up? Should I lightly sand the rest of the bore for some new crosshatching to help the ring seat?

Sounds as though just about any 44mm piston should work, so I'll just get one and see if it matches up!

 

[A100HVA]

http://www.husqvarnaretailer.com/ddoc/HUSB/HUSB2005_USen/HUSB2005_USen_B0501008_.pdf
http://www.husqvarnaretailer.com/ddoc/HUSI/HUSI1983_AAaa/HUSI1983_AAaa_I8300012_.pdf IPL for 1983 saw white top
http://www.husqvarnaretailer.com/ddoc/HUSI/HUSI1989_AAaa/HUSI1989_AAaa_I8900012_.pdf IPL for 1989 saw grey top

i'm thinking that you might have "85" saw, but really don't know.
hope these IPL'S help you out.

 

[tmessenger]

I use 320 wet and dry with WD40 after any transfer has been removed with acid, also replace both crank seals while you're at it.

Hey guys,

Thanks for all your responses. Getting close to placing an order for parts. Based on some research, looks like lean seizure. All the rubber stuff is almost thirty years old, so that was likely it.

A100HVA, the serial is 5032843... what year do you think it is?

Skippy, thanks for the link. Muriatic acid is kinda scary, but I guess I'll give it a shot. Do you think sandpaper alone would clean that up? Should I lightly sand the rest of the bore for some new crosshatching to help the ring seat?

Sounds as though just about any 44mm piston should work, so I'll just get one and see if it matches up!

 

[SawTroll]

That saw was made 1985 week 03 according to the serial number - so it can't have been bought in 1983, unless at least the left halv of the case is donated from another saw.....:msp_wink:

 

[SawTroll]

http://www.husqvarnaretailer.com/ddoc/HUSB/HUSB1990_USen/HUSB1990_USen_B9000024_.pdf

try this for starters.
yours needs piston,don't hone cylinder.
post serial number

Light honing is fine, after removing any alu, provided a ball hone is used.

 

[Teotwawki]

Hey guys!

Ok, thanks for all the advice! Today I got around to using some muriatic acid on the cylinder. I did three separate applications (using a q tip) letting the acid sit there for about 3-5 minutes each time, and rinsed with water after. Then I did some very light sanding with wet/dry sandpaper and WD40.

Above the port feels super smooth and looks OK, but right below the port where there are the two black marks it is a tiny tiny bit rough. I can't feel it with my finger, I have to use my fingernail and search around for the spot where it just lightly catches. I honestly can't tell whether they are pits or bumps, it's that small.

I never saw the acid bubble or anything, but the first application turned a little bit white. I did not heat the cylinder.

Here are some pics. Do you think I should use some more acid, or sand some more? I want to be conservative because I really don't think I can get another cylinder for this saw and it has a lot of sentimental value. If I could have gotten a cylinder I wouldn't be mucking around with this acid lol. If any one has a lead on a new one lemme know!!!!

Ok... pics...

 

[Rokon]

Those scratches are less than ideal, for sure. More acid WILL NOT take that out. If it were me, I would put a new piston and ring on and go with that cylinder.

Most likely you want it to run good, cut a couple hunks of wood, then put in on the shelf for story time. I wouldn't think a scratched cylinder would ruin the value of that.