Jonsereds xf problems

[Bob baldrey]

Hi there I'm based in the UK and have an early jonsereds xf.
The saw used to be my workaday but after developing a fuel problem it got shelved.
After replacing the diaphragm in the non return valve on top of the fuel tank I had fuel and the saw ran for a while and after setting the carb basic settings ran well.
When I returned to the saw later it started intermittently and then not at all.
When you pulled the starter it kicked back violently so I presumed that the timing was out.
After trying to set the timing with very little information available it will not spark at all now no matter where I adjust the back plate . Points are adjusted to .33mm and the timing is set to fire when the piston is around 4mm before top dead center.
Any advice or specs would be greatly appreciated. Sorry about the SA but I'm new to this forum stuff.
Many thanks Bob.

[HolmenTree]

Welcome to the forum Bob, beautiful old 110cc  classic you have there. Was designed by a Volvo engineer who also designed the famous 007 James Bond Volvo sports car.

I can't give you much advice but you should vacuum and pressure test the crankcase. It has a reed valve from my information and that may have something to do with the problem you're having.

Even though you set the points gap the contacts may he burnt and possible defective condenser which may have allowed the point contacts to burn up.

Sounds like you changed the fuel tank vent?

Don't give up on it as it's too nice of a saw to throw into the corner.

[Bob baldrey]

Thanks HolmanTree, had the fly wheel off and the points are ok, cleaned them and surrounding areas reassembled and adjusted the points again and I have a good spark now but is kicking back so hard it'll bust your hand.
As you say I think perseverance is the key.

[motzingg]

Are you sure timing is 4 mm BTDC and not ATDC?  

Also, that sounds pretty far advanced just to me, the kickback would be timing too early. 

I'd try it again around 2 mm BTDC. ( i assume you are measuring in piston travel) 

it would be more accurate to set it using a timing wheel on the flywheel.  usually if i have problems i think are timing related i'll use 2 methods and make sure both are giving me the correct timing- piston travel with a multimeter to check points open, then spinning it with a drill using a timing/strobe light. 


good luck! 

[630red]

welcome,is the flywheel key in tact

[Bob baldrey]

Hi motzingg
I got the 4mm btdc (3.7mm) by trying to translate from an old Swedish hand book, info seems quite hard to come by , I may have made a mistake, l have moved the back plate almost all the way clockwise and then did a static timing check with a multimeter and the piston is around 6mm from tdc.
I'll move it all the way and see if it will actually bring it atdc.
I couldn't use a strobe on it because as far as I can see it has no timing marks on the fly wheel or the outer casing.
Thanks for the advice about using the multimeter previously I had been trying to visually check the points opening which obviously wasn't nearly accurate enough.
Thanks again
So I reread you post, to check the timing with a strobe do you make your own marks on the fly wheel and the housing with the aid of a timing disc?
Previously being a motor mechanic we were spoiled by having manufacturers marks to use.
I haven't had to put this kind of stuff into practice for over 20 years.
Just one of the reasons I love working on these old saws, they make you think.

[Bob baldrey]

Thanks for the advice on the xf got her running now, find it hard to find parts over here in the UK for the older saws, how is it in the states?.
Have just brought a jonsereds 621, not sure of the year but parts seem a bit easier to come by (recoil spring and carb kit).
Hopefully post some pics of the xf and the 621 when I get it finished.

[HolmenTree]

Bob, you'd have better luck finding parts for the XF in Sweden where it originated from.
There's a fella named Magnus who runs a Chainsaw collector website who'd find you some parts. 

[Larrimer]

 <br Hey !  Here is my Jonsereds XF.  If someone have a clutch to sell I would be happy to buy.  Need also those spacers that comes with the drum.  I have the clutch...but not the drum ! The saw is a runner...but not tested with the bar and chain of course. Would love to have it complete and  test it.  I have bar and chain 404 that is on my XG and I belive it is same bar mount type.


 
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