Jonsered 49sp Vapor lock?

[finnyct90]

Hi All,
one of my 49sp's runs good for only a bit and then is real fussy and won't idle etc. I notice that once the saw is run for a bit, it will sit there and sound like a plastic gas tank that is trying to match the outside pressure. If I loosen the gas cap and "burp" it, it will start and run fine for a bit. I thought I saw a thread about this but now I can't find it. thanks in advance.
Spencer......(if you worry about the ticks...then the ticks win!)

 

[PB]

Sounds like you have a clogged fuel tank vent.

I can't remember where it is routed on the 49, but I am sure someone will be along to help you locate it. I want to say it is near the clutch, but not positive.

 

[finnyct90]

vent thingie

Well, I changed that little fitting with the ball bearing in it, grabbed one out of a parts saw, that seemed to pass more air. I'll see how the saw acts this afternoon, I'm going after some red oak later.
I'm not sure if this is the fix or not. please feel free to set me right if I don't have this right.
Spencer

 

[LittleFella]

My 49SP was doing the same thing and it was just the vent tube for the gas tank was clogged. A little Id Red and some compressed air fixed it.

 

[sundance]

Id red?? I'm lost.

 

[bob-o52]

Too many times I've had trouble with fuel tank vents, bad news is that used to be the last thing I checked. At the first sign of any problem, That's the first thing I check. More than 1 of my vintage Homies has had a new ignition, carb kit, that it probably didn't need. ( Poor people have poor ways ) !

 

[LittleFella]

ID Red is an industrial grade degreaser in an aerosol can. We use it where I work. Pretty good stuff. It's made by ZEP.

 

[Cantdog]

Well, I changed that little fitting with the ball bearing in it, grabbed one out of a parts saw, that seemed to pass more air. I'll see how the saw acts this afternoon, I'm going after some red oak later.
I'm not sure if this is the fix or not. please feel free to set me right if I don't have this right.
Spencer

Just curious, how did the changed vent work out? Problem solved? If not the first thing I check (as strange as it seems) is check that the cyl bolts are tight. 49s seem to get loose sometimes and it doesn't take much of an air/vac leak to make them run poorly at low speed. Also check that the muffler bolts are tight. All mine make strange sounds when shut off after a good run, but it has never seemed to be a problem. The next thing I check is the carb to manifold gasket. If the carb mounting bolts are loose this will do the same thing. Also make sure that the gasket is the correct one and seals the impulse corridor as the ones that come in a carb kit don't. Just a couple more thoughts for you to ponder. I 've had one or more of these little guys ready for the wood since 1977 and have never taken one to a shop for anything. They are nice saws IMHO!! Good luck and let us know how it's getting along.

 

[roughcut]

49sp vapor lock

My 49sp is leaking a lot of gas out of the vent tube. Would this be caused by something being plugged? Also, it sounds like the gas is boiling in the tank after working it hard and then shutting it down. It has sounded this way for a long time but always starts right up and runs well. Anyone ever had this problem and know what may be causing it?

 

[Cantdog]

49sp Passing Gas

My 49sp is leaking a lot of gas out of the vent tube. Would this be caused by something being plugged? Also, it sounds like the gas is boiling in the tank after working it hard and then shutting it down. It has sounded this way for a long time but always starts right up and runs well. Anyone ever had this problem and know what may be causing it?

Hi roughcut, If you are leaking gas out of the vent tube it is probably a stuck vent valve. It screws into the top of the tank on the left hand side under the carb. The ball that you find inside the valve body should move in and out freely.

As I said above, all my 49s make funny sounds when setting after use. Not really boiling sounds but I think air entering the tank through the vent valve as the fuel cools and contracts, creating a vacume. I'm not sure that's what you are describing on not. But all mine always do it and always have and always start and run fine.

I would take the valve out and check that it is working properly. Good luck!!

 

[roughcut]

49sp vent valve

Cantdog,
Thanks for the advice. Bought this machine for $40.00 about 20 years ago not running. Tightened the cylinder bolts and it has been running ever since. Haven't had to use it much till now and I think it is going to need some TLC.

 

[Cantdog]

49sp

Hi roughcut, the 49sp is the only saw that I bought new. (1977) Yours for $40.00 was an OK deal back 20 yrs. ago even not running. My first 621 came to me as a set of two for free about 15 yrs ago. Well, they sat under the bench and gathered dust until finaly last fall (about the time I discovered this site!) I pulled them out and blew the dust off them. A friend gave them to me LHAO and said "you want 621s? here you go". They were pretty sorry looking items.
But one had the parts the other needed. I started with the one that felt like it had the best compression and the first thing I found was same as you, cyl bolts loose. I took it apart and made a new gasket from the pattern of the old one and put the cyl back on.
I just moved all the best parts to that saw and in about 4 hrs she was running perfect with 205 lbs comp. cold!! Other than broken parts the loose bolts was the only thing wrong with it, engine wize. I don't think it had all that many hrs on it. I used it all last winter with no problems at all.

The 49s are real good saws IMHO, I like the way they cut and the way they sound. Where yours has sat a lot I'd (1)rebuild the carb, (2) inspect and/or replace the fuel line and filter, (3) make sure that the cooling fins are free of any built up sawdust and oil, (4) pull the flywheel and clean and set the points to 0.016", (5) grease the clutch bearing, (6) make sure that your air filter is clean with NO rips etc.(7) use the best quality 2 stroke chainsaw oil you can get your hands on (sthil prem or ultra, Husky, etc. the good stuff) and I bet that saw will surprise you how many hrs are left in it.

Good oil is essential as good pistons for those are real hard to come by. (If you have a good one try to keep it that way!!)

Good luck and have fun

 

[roughcut]

49sp tune up

cantdog,
Thanks for all the good information. I'm going to start going over it this weekend. I just recently bought a house w/26 acres so I now have lots of cutting to do. I need to start looking for a back up... just in case.
Thanks again!

 

[Cantdog]

49sp++++???

cantdog,
Thanks for all the good information. I'm going to start going over it this weekend. I just recently bought a house w/26 acres so I now have lots of cutting to do. I need to start looking for a back up... just in case.
Thanks again!

HAHAHA!!!! That's how it starts!!! Once you get a back up-----you'll need a back up for that as well!!!!

Soon you won't even be able to cut wood cause you can't decide what saw to use!!!

Good luck with the 49sp!!!

P.S. Welcome to the site. There is a huge amount of onfo and experience on here. Truely an asset to folks who want to know anything about power saws.

 

[finnyct90]

still hissin

Hi Cantdog,
changing the vent did not change the hissing sound after the saw is run. I got real busy into early summer and just set the old 49 on the shelf till I get some time to study it a bit. I been running a shindiawa 488 as a replacement for the 49...not nearly as cool or as great a saw.
I hope to get my 49 going before fall and if I don't it has served me well since 1981.

 

[Cantdog]

Hissing 49s

Hey Spencer I have been wondering how you made out with your 49. I know it still hisses/gurgles but did changing the vent affect the problem of it not running/idling well after it's warmed up? If it continues to run poorly I would check the points and make sure that they are set correctly and are clean.
If they have worked together from wear on the cam lobe it will retard your ign. timing and may be causing some of these problems. Just another thought. How is your compression? It also may be just a worn ring that is to thin and loses tension enough to not seal well once hot.
These are just a few possibilities.

 

[sirbumpy]

timeless wisdom

After hours of reading these threads and correcting loose head bolts, dirty needle valves etc. I succumbed to sending my 49sp to a highly recommended dealer..... coupla hundred bucks later she purred like a kitten and cut like a hot knife..... for 20 minutes .... what the?

So back to this thread and after lubing the vent valve she just don't wanna stop cuttin' wood.

So here's to you all one more time ......cheers mate!!

 

[HarleyT]

There's an inventory blow out on ID RED II right now which is the same as ID RED. It's while supplies last! If you're interested, let me know!

You are not helping sell your product in any way..