Ignition test on the old Bosch points ignition

[Steffen]

Im working on an Bosch ignition on a Stihl 07, but im having some problems.

all bosch ignitions i have worked on so far just needed to clean the points and if that did not help, i changed the capasitor and then there was a spark.
I have done that on this ignition but still no spark.

I then took the coil of and fittet another, still no spark. i tjecked the sparkwire and there was connection all the way though. I tjecked the points, when closed there was connection and when open there was not.

Is there a way to tjeck if the parts in an ignition is working without haveing the special tools? I only have a multimeter.
I must i am no expert when it come to ignitions... I have not worked a lot on them as they mostly work on the old Stihl saws.

Do any of you have a guide or can talk me though what to start with and how to from parts to parts to find out were the problem is??

Thanks guys

 

[JonCraig]

Dumb question, but have you tried a new plug? Do you have an inline spark tester? I have one like this and find it invaluable.

 

[Steffen]

Yes new plug, and has removed the killswitch.
No i dont have that tool...

 

[JonCraig]

Oregon 42-087 is the part number for the one I have. I paid ~$10 for it, I think. I'm sure there's a sponsor here who has it for a great price w/ fast shipping. And there's Amazon, ebay, etc. as well.

I use it multiple ways. With the plug out and the tester in the plug boot (with the alligator clip on a cylinder fin, or some other good ground), I pull the rope a few times and watch to see if the spark fires at even intervals. I also sometimes chuck a socket into a drill and use the drill to turn over the engine to watch how consistent the spark is. Finally, you can put the plug in the engine and insert the silver lead of the tester into the plug boot and clip the alligator clip onto the end of the plug. With this setup, you can watch the spark as the engine is running (or trying to).

Definitely worth the small investment, in my opinion.

 

[Steffen]

But my problem is there is no spark...

 

[JonCraig]

How do you know? Just because the saw isn't popping? I have worked on several saws that "just wouldn't pop", and it was probably 50/50 as to whether or not it had spark or not. With a tester, I could accurately diagnose whether it was spark related or not.

In a pinch, I've used a 2' piece of wire. Strip 4" of insulation off one end, wrap that around the threaded portion of the spark plug. Ground the other end. With the plug installed into the boot, but out of the saw, pull the cord and watch the plug gap to see if you have spark.

Other things to test... Is this the original flywheel? Do the flywheel magnets still grab a screwdriver well? Is the flywheel key sheared? Do you have the coil gap set to .010? Points to .016 and plug at .020?

 

[Steffen]

Just because im no expert in ignitions, that dont mean im an idiot on saws... I have tjecked the sparkplug outside the engine and there was no spark. I then cleaned the points, no spark. i changed the condenser as it is offent bad on these ignitions. Still no spark. I then disconectet the killswitch as its could be grounded all the time. Still no spark. I then changed the coil, still no spark...

Then i got a bit lost, and maybe some of you experts in ignitions have a guide on how to control the parts of an ignition to se what might be the cource of the fault.

 

[JonCraig]

Didn't mean to insult.

Do the flywheel magnets still grab a screwdriver well? Is the flywheel key sheared? Do you have the coil gap set to .010? Points to .016 and plug at .020?

Made sure of these?

 

[Steffen]

No problems mate

Yes the flyweel is still magnetic and the key is fine and in the right place.

I have not checked the gabs, but i can so later this week when i have the time.