Stihl 045av Super electronic ignition

[b7100]

I've been rebuilding a 045 Super av with electronic ignition for a neighbor. So far I'e been able to locate bearings and a piston. Got everything together and had good compresson but very weak spark. Is there any way of testing and repairing this system or do I just replace the whole unit? Would weak flywheel magnets cause a weak spark? I know some of these parts are no longer availiable. Does anyone know of a source for these parts?:help:

 

[Lakeside53]

The parts are a problem, and really expensive. Do you have the two piece Bosch Flywheel/ignition system or the SEM igntion with the one piece flywheel? The latter is easier as it's the same module used in the TS350/360 concrete cutoff saw, and there are a bunch of those around.

 

[rupedoggy]

I am sure you guys will jump on me for saying this so go ahead. This is about the third post in a short time about weak spark. I have had the experience of no spark and a spark, but not a weak spark. Seems these saws modules either work or don't. People that come on here and say weak spark I would like to ask this question, "how do you know it is weak?". If a person is used to a car spark then the saw seems weak, (but it isn't). I have had several guys come to my shop and say that their spark is weak. It looks like it in the daylight. When I take out my tester plug and it jumps a spark on a plug with a missing electrode, I ask them "is that weak?". Point is I have seen saws out of time and saws that had other problems, but if they are sparking, it just doesn't seem to be the ignition most of the time. Mike

 

[Lakeside53]

Perfectly valid rupe.. and I see it all the time... If it work with the ground electrode missing or bent straight up, kit will fire in the saw.


The "usual" failure mode for the 045/056 ignitions is either no spark at all, or it sparks for a minute or two then as it gets hot, start to misfire, wont rev high, then quits altogether until cold.

 

[b7100]

When I say weak spark I can hold on to the bare plug wire and I can just barely feel it when I pull the starter rope. When I put a plug in and ground it to metal it gets a faint spark if you pull the starter real fast. So that is what I mean by a weak spark. Would this be caused by a bad plug wire or poor ground?

 

[b7100]

I'm not sure what ignition it is. Flywheel says bosch. The module is one piece.

 

[b7100]

I took a coil off an 08 and put it on the 045. I now have good spark and compresson but It won't fire. The coil was a little different but it produced a spark. I timed it by lining up the marks. Is there ant other way of checking timing?

 

[Lakeside53]

I'm not sure what ignition it is. Flywheel says Bosch. The module is one piece.

Many of the flywheel are made by Bosch for either system Do you have a picture of your ignition module? How about a part number from beneath the flywheel?

The Bosch Ignition system is the one with the most problems.. most I see are failing or dead. The flywheel is two pieces - an outer aluminum an wheel and an inner steel wheel. The igniton has two coils on a strator plate.

The SEM ignition lies under a one piece flywheel and is a single resin-potted black module. The flywheel and module MUST be matched - you can't use the flywheel from an 08.


To check the timing you need a timing light that is battery powered. I'm not sure what the exact timing is but it should be somewhere around 20-30degree BTDC (Someone might know the exact value) To find tdc, put a screw in piston stop in the plug hole, rotate the flywheel until it stops, make a convenient mark, rotate the other direction, make a mark. TDC is exactly half way between these two marks. Take out the stop, put a battery powered electric drill on the flywheel nut and spin it counter-clockwise at 1000rpm. Make sure a plug is connected and grounded to the chassis. Don't put it back in the cylinder for this test as it will be too hard to spin.

 

[joel eklund]

Ignition coil...?

The parts are a problem, and really expensive. Do you have the two piece Bosch Flywheel/ignition system or the SEM igntion with the one piece flywheel? The latter is easier as it's the same module used in the TS350/360 concrete cutoff saw, and there are a bunch of those around.

Just to be sure... even though the coil I pulled out of my 045 that is attached to the stator plate does not look exactly like the TS350/360 the new coil will work and I can set the timing correctly? Dont want to put $ into a saw that I am not sure will work.
Thanks... appreciate all the info I can gather

 

[maico490]

Do you have the two part Bosch flywheel with the separate fanwheel? If so the concrete saw ignition won't work without the SEM flywheel which was only fitted to the late model 056 Mag11.
If you have the Bosch it is NLA and spendy if you can find a good s/h one. (Most aren't good) However someone posted recently on how they cut most of a Bosch ignition away and installed either a Atom or Nova chip. At the moment I can't find this thread but try searching under variations of "056 ignition"
One other option is that the 045 crank will have a points lobe so you could fit that ignition and flywheel.

 

[joel eklund]

thanks.... seems like i need to look into things a bit more.
appreciate the help