HI everyone I'm Paul and I'm a chainsaw addict............Hi Paul

[sedanman]

Greetings, I am new to the board and thought I'd introduce myself. My name is Paul Archer, I'm 34, currently have 4 saws 2 stihls 017(12 inch),026(18 inch) 1 homelite XL12(20 inch) (blue) and a Jonsered 49sp(18 inch). I found this place when John Lambert metioned it on e-bay (I'd love one of those 090's but have no use whatsoever for something that big). All of my saws run but the 49sp has a full throttle running problem I hope I can figure out before I cook it, it's my fist attempt at bringing one back from the dead as I've just replaced the top end. The next saw I am looking to buy is either an 044 or 046 in about the 28 inch range.

 

[tundraotto]

hi paul - so tell us about your problem - with the jonsered....

 

[sedanman]

A little history, got the saw from an old (80ish) friend who had it seize on him. I searched long and hard for replacement parts before I scored a sweet used piston and cyl. I rebuilt the top end with a new ring and overhauled the carb in which I found debris. With new parts and a clean carb I thought I was home free. The saw starts and idles beautifully but will miss at full throttle and bogs down in wood. Also, after the saw is turned off there is a sucking or hissing noise but I can't seem to isolate its source. I've had the muffler off many time to make sure the piston still looks good, it does. The high speed screw is one turn off its seat and I don't own a tach that will work on a 1 cylinder engine. I want to fix this saw for two reasons: 1, I can't stand to see anything tossed out when there might be life left in it and 2, I want to give it back to the old dude I got it from because he can't stand the saw he replaced it with.

 

[JimL]

Sounds like you need to lean it out, turn the high end screw in until it runs smoothe and back it off a smidgen

 

[tundraotto]

the hissing noise sounds wrong! - did you replace all filters (ie. fuel) , what about the lines to the carb. did you rebuild the carb?

where does this hissing originate from? bottom of the saw, front, rear? im sure somebody on this forum knows what this is caused by exactly.

 

[treeclimber165]

Sounds like an air leak around the jug or case. Squirt a little WD-40 or dish soap on the mating surfaces when it's running, see if that helps you pinpoint where the case is leaking.

 

[Gypo Logger]

You should check the tank vent too.
John

 

[John in MA]

This may be something completely different, but all my gas tools suck. Er, make a sucking noise. It seems to be from the slight vacuum in the gas tank equalizing with atmospheric pressure.

You're running it too lean at WOT. The one turn thing is just a starting point. I don't use a tach--just tweak it until it "four-cycles" when you gun it.

Hey, why would you need a reason to own an 090? It's BIG! Of course, I'd probably take a Homelite 3100 if I was in that range.

 

[davefr]

Probably bad oil seals. With the exhaust port blocked you basically need to apply pressure to the intake port and see if it holds, than you need to apply vacuum and see if it holds. If not, there's a leak in the crankcase or possibly bad seals. You need to try both pressure and vacuum. Sometimes one tests out OK and the other fails. I believe www.madsens1.com might have some more info on their web site under maintainance/service.

I don't know if there's any shortcut to doing this test without making special adapter plates and having a vacuum and pressure testing setup.

 

[tundraotto]

john may have a very good point here - check out the breather valve/tube of your gas tank - this could be a reason why it starves of fuel on higher revs - the breathers plugged. this would not happen at idle as the gas flow needed is so much smaller.

 

[Walt Galer]

Howdy,

I agree. Make sure the tank vent is operating both ways first. Then check the main seal, especially on the output crankshaft end. Jonsereds, models 49 through 52 were great saws, but with lots of hours, these seals would leak. The crankshaft would actually feel loose in the bearings usually on those that leaked. I suspect the problem was too light of main bearing on that side and a rather small crankshaft. Things would get running around excessively.

Regards,
Walt Galer

 

[sedanman]

Thanks for all the info. I am leaning toward the plugged vent theory. I'm sure I did a good job on the cylinder to case seal job but can't vouch for the crank seals. The saw has probably only cut about 25 cords in the last 23 years. I did not replace the fuel line or filter. The guy I got the parts from lives close to me and said he'd look at the saw this weekend, and replace fuel lines/filter. I'll kep everyone posted on the outcome. I also just bought ANOTHER jonsered sp49 in running condition. I told you all I was addicted!

 

[tundraotto]

good deal - those filters are cheap and need to be changed on saws that have been around for a while because they gum up. also make sure he checks that vent and ill bet you money youre ready to rock and roll - youll like the jonsey!

 

[Gypo Logger]

Hi Otto, if I saw a rack like that, I would probably develope a bad case of aracknaphobia.
John

 

[Gypo Logger]

Oh, I see, nobody liked this post. Well, it just so happens to be one of my favourites
John

 

[max2cam]

Originally posted by Walt Galer
Then check the main seal, especially on the output crankshaft end. Jonsereds, models 49 through 52 were great saws, but with lots of hours, these seals would leak. The crankshaft would actually feel loose in the bearings usually on those that leaked. I suspect the problem was too light of main bearing on that side and a rather small crankshaft. Things would get running around excessively.

Regards,
Walt Galer

I have an old but great Jons. 451AV that feels "loose in the bearings" and it also has bad seals.

Did you mean that the bad seals make it feel "loose in the bearings" but that the bearings can still be good? I assumed that the loose feel came from bad bearings...

 

[sedanman]

I think Walt meant was that loose bearings take the seals out as the seal is really only designed to handle rotation not radial movement. And the result of this is an air leak which would cause a running problem. Since first posting this I have come far in my 2 cycle knoledge, far enough to moonlight 2 nights a week actually fixing them.

 

[Gypo Logger]

Hey, am I a Woodtick or not?
John

 

[sedanman]

The finest known specimen!