Early Stihl 046 coil / flywheel combos ?

[OldSaw46]

I have an early Stihl 046 with a 1128 1309 coil that has 3 legs and uses 3 bolts. The flywheel is a Stihl 1128 400 1211 with a single magnet. No spark. Ordered a coil for a 046 and received a 1122 400 1314 that has 2 legs and uses 3 bolts. A different design and No spark (still)! Can this 2 leg coil replace the 3 leg coil on the original flywheel ? Is there a magnet weight lift test - or some other test - for the flywheel itself ? The 4 possibilities that have come to my mind are: 1) I received a dead on arrival coil, 2) The new coil design won't work with the 1128 400 1211 flywheel, 3) The flywheel magnet has gotten too weak, or 4) Other. Before the saw failed completely, it became hard to re-start when warm. This degenerated to won't start at all - and multiple spark test failures, classic descriptions of a failing coil.

Testing the new, Chinese 1122 400 1314, with this latter (wrong?) coil in place, I measure 6.97 K Ohms across the primary circuit and 1.4 Ohms across the secondary circuit. With the gap set at 0.010" between coil contacts and the single flywheel magnet, I get no spark on an Oregon tester, spark plug, or the using my finger test high confidence it isn't working test. How is this failure possible?

 

[stihl86]

The coil you got is the correct part number, by part number only.
According to current, Stihl supplied parts lookup.
There's no technical bulletins in regards to a coil change that I remember or can find. There's no part numbers on the parts either. That's probably just a manufacturing ID reference.

The only change to the flywheel was a addition of a magnet set.
There are different flywheels, but they were for the Artic models for the generators.
Buying aftermarket electrical parts is a crap shoot. They work or the don't, leaving you scratching your head. Other types of parts can, at least be boogied if wrong.
I have access to all Tech bulletins and currently supplied IPLs. That's where my info comes from. Not a fading memory.
Disclaimer: I cant GUARNATEE all this info is correct.
Stihl has a nasty dirty habit of making information disappear.
I do have a old reference guide, it makes reference to a 46, but offers no info.
Check with a dealer an see if they have a test or used coil.
Any older large dealer must have a few in the bone yard.
Its tough because you may have the answer to your problem right in front of you.. But cant see it.

 

[Mad Professor]

Edit:

Whoops replied to wrong thread

 

[stihl86]

Just to add, the original part number for the coil was 0000 400 1303.
It's no longer available from normal stihl supply.

 

[drf255]

Did you check for spark with kill wire disconnected? Did you check the plug wire/lead to make certain there is no issue with it? No shorting out?

Contrary to most BS you’ll hear, most of the 024-066 coils will work on the 046. The only issue is that the 1309 coils for the 1128 series, as well as some 1122 coils, have built in start retard on them. Helps with starting. Any 1300 ”dummy“ coil should allow a 460/046/461 to have a spark and run. So you can swap any of those other models coil in to test it out.

Only time I have seen coil magnets go bad is if the get traumatized. Like the coil rubs the flywheel badly. It can change the N/S polarity of the magnets. If you have a small magnet you should be able to check that. One pole should pull magnet in and one should push it away.

Just check everything else out, including the flywheel key, before you keep tossing money at it.

 

[deye223]

My 460 has a 1128 400 1312 coil and I just put a 1122 400 1314 coil in my son's 461 and it works perfect even with the timing advance .
But yes I would check the coil leads especially where it goes into the rubber boot for the coil spring slips over the spark plug we had trouble with my son's the way they do it is stupidity.

 

[drf255]

No coil can advance timing. It cant tell what to do before magnets hit it. It can only retard timing at a given rpm.

 

[deye223]

If you are referring to my post I never said anything about the coil advancing the timing .

 

[OldSaw46]

Did you check for spark with kill wire disconnected? Did you check the plug wire/lead to make certain there is no issue with it? No shorting out?

Contrary to most BS you’ll hear, most of the 024-066 coils will work on the 046. The only issue is that the 1309 coils for the 1128 series, as well as some 1122 coils, have built in start retard on them. Helps with starting. Any 1300 ”dummy“ coil should allow a 460/046/461 to have a spark and run. So you can swap any of those other models coil in to test it out.

Only time I have seen coil magnets go bad is if the get traumatized. Like the coil rubs the flywheel badly. It can change the N/S polarity of the magnets. If you have a small magnet you should be able to check that. One pole should pull magnet in and one should push it away.

Just check everything else out, including the flywheel key, before you keep tossing money at it.

Yes I did check for spark with the kill wire disconnected. Re the plug wire, I did measure 6.66 k Ohms from the end of the spark plug connection to ground, so there is at least some flow there.
Are there any specs on testing a 1122 400 1314 coil with a VOM ?

The flywheel, its fins, and its magnets appear undamaged. Somewhat to my surprise, both poles on a small magnet that I put near the flywheel were attracted to both sides of the flywheel magnet, and repulsed by neither. Given what you said, my best guess in the moment is that the flywheel is okay and the new (Chinese) coil - is not. I am surprised that a two leg two screw coil (1128 400 1314) is a functional replacement for a three leg three screw coil (1128 1309) on the same one notch one magnet flywheel (1128 400 1211). Thanks for the help !

 

[deye223]

Yes I did check for spark with the kill wire disconnected. Re the plug wire, I did measure 6.66 k Ohms from the end of the spark plug connection to ground, so there is at least some flow there.
Are there any specs on testing a 1122 400 1314 coil with a VOM ?

The flywheel, its fins, and its magnets appear undamaged. Somewhat to my surprise, both poles on a small magnet that I put near the flywheel were attracted to both sides of the flywheel magnet, and repulsed by neither. Given what you said, my best guess in the moment is that the flywheel is okay and the new (Chinese) coil - is not. I am surprised that a two leg two screw coil (1128 400 1314) is a functional replacement for a three leg three screw coil (1128 1309) on the same one notch one magnet flywheel (1128 400 1211). Thanks for the help !

Just bang one in works fine heaps of people do it including saw builders nobody wants a limited coil .
I also advanced the timing and no problem with starting

 

[OldSaw46]

The coil you got is the correct part number, by part number only.
According to current, Stihl supplied parts lookup.
There's no technical bulletins in regards to a coil change that I remember or can find. There's no part numbers on the parts either. That's probably just a manufacturing ID reference.

The only change to the flywheel was a addition of a magnet set.
There are different flywheels, but they were for the Artic models for the generators.
Buying aftermarket electrical parts is a crap shoot. They work or the don't, leaving you scratching your head. Other types of parts can, at least be boogied if wrong.
I have access to all Tech bulletins and currently supplied IPLs. That's where my info comes from. Not a fading memory.
Disclaimer: I cant GUARNATEE all this info is correct.
Stihl has a nasty dirty habit of making information disappear.
I do have a old reference guide, it makes reference to a 46, but offers no info.
Check with a dealer an see if they have a test or used coil.
Any older large dealer must have a few in the bone yard.
Its tough because you may have the answer to your problem right in front of you.. But cant see it.

Looking more closely at what you wrote, I note you wrote, "The only change to the flywheel was an addition of a magnet set." With the "addition of the magnet set", did that change the part number from 1128 400 1211 ? The single magnet on my 1128 400 1211 flywheel is 2 3/8" long . . .

 

[stihl86]

Looking more closely at what you wrote, I note you wrote, "The only change to the flywheel was an addition of a magnet set." With the "addition of the magnet set", did that change the part number from 1128 400 1211 ? The single magnet on my 1128 400 1211 flywheel is 2 3/8" long . . .

Same part number. The bulletin came out in 2006. Looks to be just a general info bulletin. TBH, its looking more and more it's that "New" coil. A 0000 400 1306 should work OK. I would add, the flywheel key would have nothing to do with the saw making a spark. It's for timing only. Call a dealer and ask about a used one

 

[OldSaw46]

The coil you got is the correct part number, by part number only.
According to current, Stihl supplied parts lookup.
There's no technical bulletins in regards to a coil change that I remember or can find. There's no part numbers on the parts either. That's probably just a manufacturing ID reference.

The only change to the flywheel was a addition of a magnet set.
There are different flywheels, but they were for the Artic models for the generators.
Buying aftermarket electrical parts is a crap shoot. They work or the don't, leaving you scratching your head. Other types of parts can, at least be boogied if wrong.
I have access to all Tech bulletins and currently supplied IPLs. That's where my info comes from. Not a fading memory.
Disclaimer: I cant GUARNATEE all this info is correct.
Stihl has a nasty dirty habit of making information disappear.
I do have a old reference guide, it makes reference to a 46, but offers no info.
Check with a dealer an see if they have a test or used coil.
Any older large dealer must have a few in the bone yard.
Its tough because you may have the answer to your problem right in front of you.. But cant see it.

Okay Stihl86. You were right. The problem WAS right in front of me and I couldn't see it. So, fine, I'm up and cutting again. For those of you who might be interested in how I managed to get so waylaid on my path to running again, best I can figure, this is what happened.

My Stihl 046 Magnum got where it was impossible to start when it was hot. Right shoulder - pain - ugg. Then, it wouldn't start cold either. Spark plug spark test - nothing. Oregon spark tester test - nothing. Disconnect kill wire. Tests again - nothing. Finger on the plug wire. Pull. Nothing. Okay, now I've proven to myself that I really am confident I've got a dead coil, after putting my finger where the spark should be...

Look at coil and find it is a 1128 1309. Try to buy a 1128 1309. Nothing. Search on the saw model number and find 1122 400 1314 is the alleged new number. Is it really? Call the dealer. Ah the saw is made in 1994. We know nothing. The computer knows nothing. Come in, and we'll order a factory part for you - retail - with a no returns, no refunds warranty. "No thank you."

Order the part via Amazon. Get it. Hmm, it looks dramatically different, having only 2 legs instead of 3. Okay measure the gap on the old coil. 0.010" okay. Look it up and find it is "supposed" to be 0.010" (?). Others say "use a business card" but I think, "Hell, I've got a classy 0.010" brass feeler gauge. Pull the old coil and put in the new (Chinese) one. Gap it like the old one. All the above tests. No spark. Is this REALLY the right coil?

Find that coils are supposed to be matched to flywheels, and given that the coil number changed, maybe the flywheel number changed and I need a new, matching, flywheel. And where is the flywheel part number? On the completely concealed by the engine side of the flywheel. Order a flywheel puller. Get it. Pull the flywheel and find the number: 1128 400 1211. Hmm, this seems to be the same number as is called for with the new coil design. Log onto Arborist. Somebody in this thread says the new coil design REALLY should work with the old flywheel AND my old 046, assuming it - the coil - didn't arrive DOA. Well, is it dead?

I write and ask on Arborist for the resistance specs across the contacts on the coil circuits. Nothing. Write the vendor. What are the specs? The vendor doesn't know. I start thinking, "What the hell; I'm going to put this all back together and try it one more time before ordering another new coil - from a different vendor, which will hopefully be part of a different production run.

Mixed in during the above, were a whole series of episodes in my head and on the web and on YouTube about flywheels, magnets, demagnetization, "stroking" to remagnetize, field loss, measuring fields in "Teslas", and a bunch of other stuff that I went down rabbit holes over till somebody here on Arborist wrote something like, "If the flywheel isn't smashed, it's probably still fine." That turned out to be right.

"Hmm, I think I'll measure the gap I set on this new coil. Yes, 0.010". What if I use a business card?" I stick one in there. "My Dogs, that's sloppy. How the bleep thick is this friggen business card? Oh, 0.008"." Set the gap to 0.008". Half screwed the recoil starter assembly back on. Gave it a pull, and the old 046 sparked! So, as best I can figure, set it to factory (?) specs at 0.010" and it doesn't spark. Set it to 0.008", and it sparks like crazy. Bottom line, my problem was about a dozen rabbit holes I went down, multiple fronts on bizarrely secret data, and a gap that I set wrong.

Thanks for the help !

P.S. If my new coil wouldn't work at 0.010”, maybe my original coil which used to work at 0.010” quit working at that gap because the flywheel magnet had weakened with old age. Maybe if I had narrowed the gap on the old coil to 0.008” or 0.006”, it would have resumed sparking. Or maybe, the coil really did have a stroke and died. Ahh, another experiment for another day. But for today, a careful bagging and detailed tagging of the original 3 leg coil - and getting back to - cutting firewood!