Jonsered 49SP Project

[telemaster]

Greetings fellow chainsaw enthusiasts. It's been a while since I've posted, but stumbled across a great buy the other day and had to share with you folks. Neighbor had a Jonsered 49sp for sale for $30. I grabbed it right up not knowing anything about the saw, but it sure looked like a nice old saw. It will pop, but not run. Appears to be a carb issue, so the rebuild kit is on order. I've done some lurking on the site and found a lot of great info in the following threads.

http://www.arboristsite.com/chainsaw/93531.htm
http://www.arboristsite.com/arborist-101/52268.htm
http://www.arboristsite.com/chainsaw/10736.htm

And of course the Mike Acre's site: Model Profile: 49SP

I'm going to replace the fuel line, spark plug, will check the tightness of the cylinder head bolts, exhaust manifold, and carb manifold while it's being cleaned and taken care of. Never had a saw with points before. :msp_unsure: I've heard different opinions on these.... check them and file 'em to the appropriate clearance, replace with an ignition module, or leave them alone. I am more inclined to leave them be unless I have a reason to tinker with them.

Not to get ahead of myself as I have a lot of work to get done before I get to tuning, but does anyone know if these saws need to be tuned "in the cut"? I ruined a nice Poulan 245 not knowing this and being a dumb operator. Still on the lookout for new P/C for that (anyone have one?), but don't want to be in the same position on the 49sp.

Any other words of wisdom from those who have been here before are appreciated.

View attachment 281779
View attachment 281780
View attachment 281781

 

[pioneerguy600]

The only real and true way to tune a carb to any engine is to tune it in the cut. Using a tach to set a factory stock engine is ok and safe but once an engine or muffler is opened up then tuning with the tach goes out the window.

 

[R/C Pilot]

Your 49 SP looks to be fairly low hours and in pretty nice shape. I was given a 49 SP last fall and was told it needed a coil. A spark plug fixed the coil problem. I just tune mine to be 4 stroking good out of the cut. They call for 25 to 1 oil mix, but I am running mine on 40 to 1 just like my other saws. Nice saw. Be careful NO Chain Brake.

 

[moody]

That saw is old enough you won't have factory rpm recommendation. Tune it to 4 stroke no load and adjust it in the wood from there.

 

[telemaster]

Thanks for the replies. I'll share more on the progress as I get the carb kit and tear into her.

The art of tuning a saw has so far eluded me... I'm a noob when it comes to that, but I can rebuild almost anything. Honestly, I usually get so frustrated with tuning that I take my saws to the local shop for them to tune. It's cheap, and they do a great job. BUT I want to learn to do this myself. When I get there, I'll be asking a lot of questions.

 

[Cantdog]

Actually no load rpm for a 49sp is 10,800..but as said tuning in the wood is the proper way to fine tune it.

When you rebuild your carb do not use the supplied carb to manifod gasket.....its outside dia is to small and will not cover the impulse corridor completly.

Either reuse the original if it's in good shape, make a new one using the supplied one as a template and just make the impulse side large enough to cover the impulse corridor, or if you have a Husky dealer handy...go get a carb gasket for a 61,266, 268, 272.....or if you have a Jonsered dealer closer one for a 630...don't use any sealer either...just dry...

That looks to be a very nice example...

 

[ckelp]

i have a complete bottom end and a carb PM me if you need it

 

[telemaster]

don't use any sealer either...just dry...

This is good info. I was going to reuse the old gasket and use a sealer. I've read of the problems with the new gaskets not covering the impulse corridor. There is a Husky dealer in town, and a Jonsered dealer about 35 minutes away.... worth the drive for a new gasket. Do it right, do it once.

 

[telemaster]

Day 1

Had a couple hours this afternoon to start the tear down... didn't get too far, and focused on the carb and gas tank. Once I got the carb off, I cleaned up the air filter and the airbox. Then I decided to drain the tank and see what was in there. Glad I did. The fuel line had disintegrated inside, pieces were floating around, and the filter was not attached to anything.

The filter is cool, in that it can be taken apart with a flat head screw driver. I am sure many of you have seen this before, but I hadn't. I took it apart sprayed it with carb cleaner, put it back together, filled it with more cleaner, then blasted it with 100psi from the air compressor. Repeat a few times. It can probably be reused, but does anyone know if installing a different filter could affect the running of the engine? This may be a dumb question, but I've decided to ask a ton of questions this time around instead of "learning from my mistakes"... bear with me some of these questions could be out there.

Here's a picture of what I pulled out of the gas tank:View attachment 282015 You can ignore the carb manifold gasket... that was not floating in the tank!

Pealing paint inside the tank:View attachment 282014
Is this something to be worried about? I blew the tank out with the compressor and most of the flakes came out, but not all. Just install a new fuel line/filter and forget it, or do I need to repaint the inside of the tank? I can't imagine how much junk was sucked into the carb with it running with no filter for who knows how long. The carb rebuild will fix that though.

Oh yeah and the SN on this saw is: 688897

 

[Cantdog]

Good work.....back in the day you could buy just the felts for the filter and that was how you did the maintenance on it. If you can blow through the filter it will work fine....a different filter won't change the running of the saw but is not needed as you already have best filter for the saw.....blow out the sintered bronze inner filter well too. Note the metal clip in the pic next to the fuel line....this is NOT crimped.. do NOT throw it away.....when you put your new fuel line on the filter put this on the line and slide it up out of the way until you have the line installed on the filter...then slide this collar down over the line and the nipple onto the filter....this will hold the the filter on the line. Another cool thing... as long as you know how it works!! LOL!!!
The paint in the tank is not so good but pretty normal on a saw that has sat for a long time. I usually take a hand full of nuts and bolts and shake them in the tank with a little mix to loosen up the flakes...drain and repeat as necessary until the fuel comes out fairly clean. I wouldn't bother painting the inside of the tank...

 

[telemaster]

Day 2

Ok. Disassembled the carb and cleaned as much as I could with carb spray cleaner. The original gaskets we welded to the carb body... don't you just love that? I have a 1 gallon can of Berryman Chem Dip for carb cleaning. I've used it on motorcycle carbs with good results, so thought I would try it on this one. I took out the throttle butterfly valve first, because there are some plastic bushings on the rod that I thought might disintegrate in the Chem Dip (why risk it?). Then I let it soak for 24 hours, gaskets were still attached, but mostly pealed off. Another blast of carb cleaner and back in the chem dip for another 24 hours. This time they came out looking pretty good. Any gasket that was left over came off with a brass brush and a scotch bright pad.

Now for the reassembly. Like I said above, gonna ask a lot of questions on this one. I put the carb back together in the following order. Does this look right?

View attachment 282744

When I was reassembling, the metering lever was pushed way down... maybe this is normal, but I don't remember it being like this when I disassembled the thing. Just because I don't remember, doesn't mean it wasn't that way.:msp_unsure: Does this look normal? In case you are wondering, I did get the button on the diaphragm inserted into the lever when I installed it.

View attachment 282746

Next, I had to remember how to install the throttle butterfly valve and return spring. Should have taken pics before I took it apart. :doh: It works as it should. Anyone see anything wrong with this?

View attachment 282747View attachment 282748

Well it's all back together. Hopefully, I did it correctly. The next step is to clean the loose paint in the tank, and wait for the new manifold gasket to arrive... later this week.

 

[Cantdog]

Gaskets and diaphrams look to be in the correct order.

The metering lever must be set flush with the car body around it.....make sure the spring in installed correctly under the lever. Make certain there is nothing under the metering valve......I have never seen a metering lever that far out of adjustment.....verify that everything is OK and installed correctly then bend the lever until it is flush with the deck of the interior of the carb surrounding it.

Not sure how you went about it but when reinstalling the throttle plate you must back the idle adjustment all the way off so that the plate centers itself in the bore when fully closed before you tighten the screw.

 

[Cantdog]

Sorry my mistake.....on this carb the idle is all they way off when the carb is removed...but the throttle plate must be centered either way.


And on a second look is the spring even under the metering lever??

 

[R/C Pilot]

I agree looks like the spring under the metering lever has been left out. The rest looks good.

 

[telemaster]

Problem Identified

OK, so I took the needle and lever completely out to see what was going on. The spring was installed correctly, but the tip of the needle is rubber--which had swollen considerably after being soaked in the Chem Dip. I've never seen a needle with a rubber tip, hey, live and learn. Thankfully the carb kit I got came with a new lever and needle.

The left is the new needle/lever and the right are the originals. View attachment 282823

Ok got that all installed... here is a picture of the lever now. It is not flush with the bottom of the "bowl", but it is flush with the surface where the gasket sits. Is that correct?
View attachment 282825

Next, just to show you guys, here are two pics of the butterfly opened and closed. You can see there are two pin holes in the carb body that the valve splits when shut. I think it's pretty well centered, before I put the screw in I worked the valve back and forth a few times to get it to center itself. Actually looks to be sitting exactly where it was before, based on the wear lines in the carb.

View attachment 282828View attachment 282829

Everything is literally finger tight has I haven't used a screw driver yet, knowing I would be taking it apart a few more times. Do you guys use lock-tite on any bolts without a washer? There is only one bolt that doesn't have a washer, and it's what attaches the throttle bushing to the butterfly valve hinge (rod). Seemed to be some remnant of lock-tite when I took it off, but not sure if that stuff degrades in the presence of fuel and if it's worth it.

Anyway, thanks for the input. I appreciate the help you guys are providing!

 

[Cantdog]

Throttle plate looks good.....If I were going to loctite anything it would be this screw...I don't loctite anything else.

Just out of hand you should use all the new parts in a full carb kit that pertain to your carb (except the carb to manifold gasket on these old Jonsereds).....you already bought it...refresh everything at once. All chainsaw carbs that I know of utilize a rubber tip on the valve...sometimes it's silver and hard to tell but rubber none the less.

Your metering lever is much better but must sit flush with the carb body when in a relaxed state, not the gasket surface. I use a couple small needle nosed pliers to hold the valve end and bend the lever side until this state is achieved....this is the correct setting for Tilly HS carbs.

 

[telemaster]

Throttle plate looks good.....If I were going to loctite anything it would be this screw...I don't loctite anything else.

Just out of hand you should use all the new parts in a full carb kit that pertain to your carb (except the carb to manifold gasket on these old Jonsereds).....you already bought it...refresh everything at once. All chainsaw carbs that I know of utilize a rubber tip on the valve...sometimes it's silver and hard to tell but rubber none the less.

Your metering lever is much better but must sit flush with the carb body when in a relaxed state, not the gasket surface. I use a couple small needle nosed pliers to hold the valve end and bend the lever side until this state is achieved....this is the correct setting for Tilly HS carbs.

Ok. I'll get the lever flush with the carb body tonight and bolt her all together. Roger on the lock-tite Again, thanks for the feedback, this is a great online community you guys have going on here. Happy to be a small part of it.

The carb kit also came with two small dish looking things (one bigger than the other). I can see where they go in the carb, but not sure how to pull out the old ones without damaging anything (being extra cautious on this saw as I ruined one in the past being all gung-ho). Then there is the question of installing the new ones after removal of the old. What do these things do? (sorry no pictures until tonight).

 

[telemaster]

I agree looks like the spring under the metering lever has been left out. The rest looks good.

OK, I have to ask. What kind of RC pilot are you? What do you fly? I grew up flying with my dad and brother, but haven't flown in years. Dad was always into the bigger planes with gas engines. Started with Zenhoas (G38), but then we got into aerotowing and had some monsters. The coolest one was a 46% Ultimate. I think that had a DA 150 or 200 twin. Don't get me wrong we still flew the smaller stuff. I learned when I was about 10 on a .20 powered all foam cub, nothing a little epoxy could fix to get that thing up and running after all the beginner hard landings.

Sorry about the off-topic post. I'll keep this offline.

 

[Cantdog]

Ok. I'll get the lever flush with the carb body tonight and bolt her all together. Roger on the lock-tite Again, thanks for the feedback, this is a great online community you guys have going on here. Happy to be a small part of it.

The carb kit also came with two small dish looking things (one bigger than the other). I can see where they go in the carb, but not sure how to pull out the old ones without damaging anything (being extra cautious on this saw as I ruined one in the past being all gung-ho). Then there is the question of installing the new ones after removal of the old. What do these things do? (sorry no pictures until tonight).

These are the welch plugs...These I try to not replace unless needed....these are "covers" to the the fuel inlet orifuses in the bore. They have to be very carefully removed by drilling a small hole in them no deeper than they are thick and then prying out with an awl or other similar pick. The big one covers the two idle holes by the throttle plate when closed... the small one covers the "H" circuit. To reinstall..note they are concaved/convex....they sit down on a lip in the carb body...they go in with the convex side pointing out and you then gently strike (once) dead center with a suitable drift or punch to flatten them out thus forcing the outer edge into the body and creating a tight seal....you can also apply a dab of pretty (your choice of color) fingernail polish to insure a proper seal afterwards if there are any doubts.

Did you install the new final fuel filter screen in the carb body on the backside of the where the metering valve seats...accessed through the top cover?

 

[telemaster]

These are the welch plugs...These I try to not replace unless needed....these are "covers" to the the fuel inlet orifuses in the bore. They have to be very carefully removed by drilling a small hole in them no deeper than they are thick and then prying out with an awl or other similar pick. The big one covers the two idle holes by the throttle plate when closed... the small one covers the "H" circuit. To reinstall..note they are concaved/convex....they sit down on a lip in the carb body...they go in with the convex side pointing out and you then gently strike (once) dead center with a suitable drift or punch to flatten them out thus forcing the outer edge into the body and creating a tight seal....you can also apply a dab of pretty (your choice of color) fingernail polish to insure a proper seal afterwards if there are any doubts.

Did you install the new final fuel filter screen in the carb body on the backside of the where the metering valve seats...accessed through the top cover?

So what I am hearing is leave the welch plugs alone unless I have a problem. Good to know how they work though! I think the soak I did dissolved anything that could have been stuck in there (unless there are solid bodies... dirt, etc.).

No, I have not yet installed the new final fuel filter screen in the carb body. The kit did come with a new one. Was going to do this tonight. Seems to just be pressed into place with nothing holding it.