Replacing Ignition Coil Windings

[Vintage Engine Repairs]

Hi chaps,
I have an Stihl 045 points version ignition coil.
I have tried it for spark and it’s on its last legs. Blue / yellow spark, only just bridges the plug gap. If I open it up on a spark tester to test coil strength it just stops.

I then decided to test it on a multimeter and the secondary winding reading was so far out. All electrodes were clean, contact surfaces were good.

Anyway, with enough desire I’m sure it’s possible to replace the windings, it’s just knowing how and what to use to replace them with, as well as getting to them without total destruction. Has anyone taken a coil apart?

Should read 5-7kohms it’s nearly 40 kohms.

 

[Jasonrkba]

I was curious so i dissected a blue coil.

 

[Jasonrkba]

I cut it with a hacksaw. I did this a while ago and figured this would come up on here one day. Lol

 

[Okie]

I'm wondering why you are farting around with a bad coil when it should just be replaced?
Like is it obsolete, NLA or???

I see some coil for the 045 on-line for like less than $20

Some of the stihls can be replaced with a Module coil, no points.
On some of the Homies that have the NLA Blue coil of Death electronic ignition I take the old bad module coil off the core laminations and press on a Stihl Module, I have to use my old core for the coil.

When the secondary on a coil reads like yours it is usually burned to wher eit has carbon tracking.
AND not feasable to do a hand wind of the secondary windings. (and then epoxy coat.

 

[pioneerguy600]

Hi chaps,
I have an Stihl 045 points version ignition coil.
I have tried it for spark and it’s on its last legs. Blue / yellow spark, only just bridges the plug gap. If I open it up on a spark tester to test coil strength it just stops.

I then decided to test it on a multimeter and the secondary winding reading was so far out. All electrodes were clean, contact surfaces were good.

Anyway, with enough desire I’m sure it’s possible to replace the windings, it’s just knowing how and what to use to replace them with, as well as getting to them without total destruction. Has anyone taken a coil apart?

Should read 5-7kohms it’s nearly 40 kohms.View attachment 900724

Sure can, Tom. Just need 5380 feet of .004 enameled copper wire and about a years worth of mucking about skinning the outer cover off, unwinding the old copper wire, clean the core, begin rewinding the new copper with no overlaps, apply a insulating coat of varnish on each row layer til topped up, then make a cover to seal the exterior from moisture and dirt/metal grindings etc. Easy peasy.

 

[Okie]

Just need 5380 feet of .004 enameled copper wire.

Correction:
5393.5 feet of .006 copper wire. the roll copper wire will cost about $30 plus shipping.

 

[HarleyT]

Have you put on new points and condensor?

 

[Woodslasher]

Sure can, Tom. Just need 5380 feet of .004 enameled copper wire and about a years worth of mucking about skinning the outer cover off, unwinding the old copper wire, clean the core, begin rewinding the new copper with no overlaps, apply a insulating coat of varnish on each row layer til topped up, then make a cover to seal the exterior from moisture and dirt/metal grindings etc. Easy peasy.

Careful, he'll think you're serious and actually do that....

 

[Bob Hedgecutter]

Careful, he'll think you're serious and actually do that....

Do Stihl offer proprietary tools for the job?

 

[olyman]

Sure can, Tom. Just need 5380 feet of .004 enameled copper wire and about a years worth of mucking about skinning the outer cover off, unwinding the old copper wire, clean the core, begin rewinding the new copper with no overlaps, apply a insulating coat of varnish on each row layer til topped up, then make a cover to seal the exterior from moisture and dirt/metal grindings etc. Easy peasy.

don't know if he still is doing it,,,but the saw shop located in cedar rapids iowa used to wind coils.....

 

[Jasonrkba]

That is one clean bugger. Certainly do as Harley suggested and change the condenser and points, do not change just one always do both. If that doesn't answer your problems at least you will have a pair of backups.

 

[pioneerguy600]

Careful, he'll think you're serious and actually do that....

We had a family friend that was an electric motor rewinder, he did the windings in an old stationary generator I owned powered by a single cylinder Scott 5 hp hit n miss. I watched him at work winding armatures, painstaking work that.

 

[Jasonrkba]

There are videos on YouTube.

 

[HarleyT]

I make my own pasta.....

 

[Vintage Engine Repairs]

That is one clean bugger. Certainly do as Harley suggested and change the condenser and points, do not change just one always do both. If that doesn't answer your problems at least you will have a pair of backups.

Thanks mate, Yes it’s new OEM points, new OEM condenser and new wiring.

 

[Vintage Engine Repairs]

I'm wondering why you are farting around with a bad coil when it should just be replaced?
Like is it obsolete, NLA or???

I see some coil for the 045 on-line for like less than $20

Some of the stihls can be replaced with a Module coil, no points.
On some of the Homies that have the NLA Blue coil of Death electronic ignition I take the old bad module coil off the core laminations and press on a Stihl Module, I have to use my old core for the coil.

When the secondary on a coil reads like yours it is usually burned to wher eit has carbon tracking.
AND not feasable to do a hand wind of the secondary windings. (and then epoxy coat.

Hey, yes It’s hard to find / NLA / very expensive and I don’t want to go the Chinese AM route if I don’t have to / can learn something.

 

[Vintage Engine Repairs]

We had a family friend that was an electric motor rewinder, he did the windings in an old stationary generator I owned powered by a single cylinder Scott 5 hp hit n miss. I watched him at work winding armatures, painstaking work that.

Impressive stuff, both his ability and dedication. Those are the of people I want to learn from.

 

[cookies]

you will first have to cut the outer case away that may or may not have part of the coil melted into it then you will need to unwind every bit of the copper windings to get to the center of the coils primary winding, recoat the primary then rewind the secondary using lacquer coated copper strand but beware if any abrasion happens you start over then it will require potting the copper in place and recovering the outside. even at 100 bucks to replace it my time and frustrations are far more valuable elsewhere.

 

[Vintage Engine Repairs]

Just need 5380 feet of .004 enameled copper wire.

Correction:
5393.5 feet of .006 copper wire. the roll copper wire will cost about $30 plus shipping.

This is all I could find, at 500m https://au.rs-online.com/web/p/copper-wire/7790696/ something like this?

What site did you find?

ideally I guess you’d need a machinists lathe and jig to get it layered perfectly. I’d need just over 3 rolls...

 

[cookies]

you must first get the coil apart and unwound to get your wire length and diameter