checking ignition coils.

[openspaceman]

Apart from pulling the plug out and earthing it and pulling the starter are there any other checks for ignition coil problems.

 

I have a ms261 which was lightly seized but ran briefly when I got hold of it and replaced bits of clutch and starter, maybe twice for 3 seconds. Now with new rings it will not spark at all. I have removed the earth lead to the on/off switch.

 

I have measured 2kOhm from plug lead through coil to earth so there is some continuity.

[billpierce]

i think coils are hard to test. check the gap between the flywheel and coil (business card apart), you can also test the earth with a multimeter, i think from the coil to the machine (try switching the switch).

 

can you borrow a known working coil from someone? check all your wires have no breaks or splits as the ht lead will earth out easily!

[openspaceman]

i think coils are hard to test. check the gap between the flywheel and coil (business card apart), you can also test the earth with a multimeter, i think from the coil to the machine (try switching the switch).

 

Yes, done that on the HT side 2kOhm resistance, Any idea on what it should be on the low tension side between switch and earth?

 

can you borrow a known working coil from someone? check all your wires have no breaks or splits as the ht lead will earth out easily!

 

Yes this is my next step

[billpierce]

Yes, done that on the HT side 2kOhm resistance, Any idea on what it should be on the low tension side between switch and earth?

 

no idea sorry. i think there is a good chance its earthing somehow if it was working well before you changed the rings

[Stubby]

Some times a coil will spark in fresh air but not under compression if its starting to fail .

[billpierce]

Some times a coil will spark in fresh air but not under compression if its starting to fail .

 

thats annoying of it

[openspaceman]

no idea sorry. i think there is a good chance its earthing somehow if it was working well before you changed the rings

 

I changed the coil without much better success, however I don't think the coil is the problem but it was the fact I was unable to spin the engine over fast enough. With chain and bar off and a very fast pull it fires but won't tickover. I'm guessing a problem with the clutch side bearing again.

[wisecobandit]

Assuming its been spaced correct regarding air gap between coil and flywheel?

Also but mainly effects husqvarnas its worth cleaning the surface where the coil mounts/touches the saw for its earth with some emery paper leaving bare metal on the saw.

[openspaceman]

Assuming its been spaced correct regarding air gap between coil and flywheel?

Also but mainly effects husqvarnas its worth cleaning the surface where the coil mounts/touches the saw for its earth with some emery paper leaving bare metal on the saw.

 

Yes I checked continuity and the gap, as I said earlier I think it's a mechanical problem as I can get it running with a really sharp pull and it will run on part throttle to full, no tickover.I'm only recently acquainted with these small stratified charge Stihls but back in the day you had to spin a Husky at above 400rpm before it would generate a spark and the Stihl is probably similar, so with a bit of drag in the motor and my feeble pulls I was probably not getting it fast enough.

 

The saw, though only 18 months old had been dumped on me with loads of bits missing. My guess it had an air leak and seized so rather than admit a problem it was left in a van and bits borrowed from it.

 

I'll play with it again at the weekend, check around the oil pump for bearing problems and clean the carb,

[openspaceman]

The saw, though only 18 months old had been dumped on me with loads of bits missing. My guess it had an air leak and seized so rather than admit a problem it was left in a van and bits borrowed from it.

 

I'll play with it again at the weekend, check around the oil pump for bearing problems and clean the carb,

 

I stripped the clutch today and the problem was blindingly obvious, I should easily have noticed that it had been robbed of two clutch springs. Seems to work fine now but no sign of weakness, holds a steady 13400 rpm on high idle. just needs a bit of logging to make sure it's ready to go back out.