Wont stop burning out magneto coils!

mew905

New Member
Sep 24, 2012
647
2
0
Moose Jaw
So I have a green bike I've had for 2 or 3 months now and it runs a 19mm Dellorto PHBG carb with a manifold to match attached by a short 1" I.D. hose. There's no air filter on the carb either. It's also been raining here on and off for over a month (not a single day yet without rain)

So I've burned out 4 magneto coils so far. The first 2 times it wouldnt start, removing the cover, lots of water poured out. I figured I shorted it out. So after that, I sealed the crap out of it using a liquid rubber leak sealant, assuming a leaky gasket. Next big rain, riding around, bike died again, a good distance from home. Stopped at a store and asked for a screwdriver. The instant I removed the bottom-most screw on the magneto cover, water poured out. it poured and poured and poured some more, the amount looked to be enough to fill the cover halfway with water.

So I dragged it over to the shop (my gf was riding it, and I was riding mine) and I've since determined water is burning it out, and getting in through the uncovered carb. So I drilled a tiny drainage hole (something like 5/32") so water wouldnt collect, and replaced the magneto and rode it home. Then at home we covered it with a tarp and no longer ride it in the rain or wet areas.

Next clear day I had made some other repairs and modifications and went to test them, and the bike wouldnt fire. It fired intermittently as it did when the other 3 magnetos burned out. But this time... there's no water in the cover, the drainage hole would have drained it enough that it wouldn't touch the coil, and the bike was covered during the rains.

So I'm at a loss here, anything I should check?

EDIT: The thin steel plate under the magnet that separates the magnet from the oil seal is bent, probably from water forcing its way through. I smacked it back down with a screwdriver but it keeps popping up. I'll replace it but I doubt that would cause the issues, but I could be wrong? Green bike runs a stock CDI with a jaguar coil plug boot (the vibrations at high speeds would shake the stock boot off the plug.

Comparative note: The black bike I've been riding for almost 2 years now has been out in the rain, both uncovered, and even riding. Has no air filter either, and never burned out a coil. It runs a jaguar CDI.
 
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2door

Moderator
Staff member
Sep 15, 2008
16,325
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Littleton, Colorado
You said you sealed the magneto cover gasket but you didn't say if you sealed the hole in front where the ignition wires exit the case. Squirt some sealant around the wires and fill that hole you drilled with the same stuff.

There is no way water got to the magneto through the carburetor. That much water would have killed the engine long before it made its way to the mag and there is a shaft seal betwen it and the crankcase.

Tom
 

mew905

New Member
Sep 24, 2012
647
2
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Moose Jaw
You said you sealed the magneto cover gasket but you didn't say if you sealed the hole in front where the ignition wires exit the case. Squirt some sealant around the wires and fill that hole you drilled with the same stuff.

There is no way water got to the magneto through the carburetor. That much water would have killed the engine long before it made its way to the mag and there is a shaft seal betwen it and the crankcase.

Tom
see the hting is the bike has a screw-in wire grommet, but I even sealed that up. I sealed all around the cover to be safe and it still found water somehow. I drilled the hole so if any water collects, it'll drain out the hole and prevent shorting out the coil but this last, (4th) time, it was dry, and still somehow burned out. My suspicions are now on the CDI
 

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
16
0
memphis Tn
If you think it's impossible to keep one dry, consider this:
Last night we had several severe storms which apparently rained sideways and flooded my bike out.
I have been popping the fuel line off and plugging it with a drill bit since my shutoff valve leaks and I hate a flooded motor.
So I came out this afternoon to ride to the store and discovered a stuck motor that refused to move an inch.
Upon investigation, I discovered the entire engine was FULL of water, apparently from it getting into the floatbowl through the tiny fuel line opening.
Even the clutch cover was full of water. (I don't have a gasket on that side)
After draining it by pumping it dry while turned over with the plug out....
It fired right up in under ten feet.
Never touched the ignition cover.
 

mew905

New Member
Sep 24, 2012
647
2
0
Moose Jaw
If you think it's impossible to keep one dry, consider this:
Last night we had several severe storms which apparently rained sideways and flooded my bike out.
I have been popping the fuel line off and plugging it with a drill bit since my shutoff valve leaks and I hate a flooded motor.
So I came out this afternoon to ride to the store and discovered a stuck motor that refused to move an inch.
Upon investigation, I discovered the entire engine was FULL of water, apparently from it getting into the floatbowl through the tiny fuel line opening.
Even the clutch cover was full of water. (I don't have a gasket on that side)
After draining it by pumping it dry while turned over with the plug out....
It fired right up in under ten feet.
Never touched the ignition cover.
That's great, but the problem isn't water anymore. I can't figure out why it's burning out magnetos every few days, but maybe my drainage hole isn't large enough for water to seep through as all the sealant I used could cause a vacuum inside the cover and retain the water (like a hamster water dropper?), I actually never bothered to check, assuming my drainage hole would drop the water out. if it's water again, it's still an issue I'd need to solve. The only thing I can think of is the water gets in the carb, and as the piston descends, it "rams" it out of the seals before it can kill the motor...
 

biknut

Well-Known Member
Sep 28, 2010
6,511
206
63
Dallas
Here's some reasons why you lose mag coils other than water shorts,

Bad spark plug wire, and or cap, causes higher current on the coil
Too much plug gap. Don't go more than 0.024" - 0.028". Same reason as above
Some people believe the stock kill switch is hard on the mag windings, and causes failure.
Probably using the white, lighting coil wire for anything is bad.
 

mew905

New Member
Sep 24, 2012
647
2
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Moose Jaw
white isn't in use, but these issues never happened until I started using the different plug cap from my jag CDI... maybe that's the problem. I'll try the spare one that comes with the kits and I'll check back in a few days. Thanks for those points!
 

biknut

Well-Known Member
Sep 28, 2010
6,511
206
63
Dallas
Don't use the stock caps, or wires from the kits. Go to an auto supply, or motorcycle shop.
 

redneck82

Member
May 25, 2014
126
0
16
concord, nh
i had a similar issue... had roughly 400-500 miles on the bike... was riding wide open making the 25 mile trip home when i heard a pop and that was the end... i went through the motor from top to bottom and couldnt figure out what went... so i gave up and bought a new kit... well.. im on day 2 with the new kit... road side with what seems like the same issue... was running wide open on a nice long flat straight and it just died... this time theres visible burn marks on the magnito... ive tried uploading pix but my phone sucks and wont let me...

any suggestions here? i mean this kit has less than 75 miles on it...
 
redneck82 were you using stock caps, or wires from the kits ? And if your engine is only 2 days old why are you running it wide open ? " im on day 2 with the new kit... road side with what seems like the same issue... was running wide open on a nice long flat straight " Sounds like a good way to burn your motor up and not break it in.
 

redneck82

Member
May 25, 2014
126
0
16
concord, nh
good point...
so... motor 2 confirmed toasted magnito...
motor 1 still a mystery...
took the magnito coil from the first, put it in the second and it started right back up...
 

THowell1975

New Member
Oct 23, 2016
8
1
0
Raleigh, NC
So I have a green bike I've had for 2 or 3 months now and it runs a 19mm Dellorto PHBG carb with a manifold to match attached by a short 1" I.D. hose. There's no air filter on the carb either. It's also been raining here on and off for over a month (not a single day yet without rain)

So I've burned out 4 magneto coils so far. The first 2 times it wouldnt start, removing the cover, lots of water poured out. I figured I shorted it out. So after that, I sealed the crap out of it using a liquid rubber leak sealant, assuming a leaky gasket. Next big rain, riding around, bike died again, a good distance from home. Stopped at a store and asked for a screwdriver. The instant I removed the bottom-most screw on the magneto cover, water poured out. it poured and poured and poured some more, the amount looked to be enough to fill the cover halfway with water.

So I dragged it over to the shop (my gf was riding it, and I was riding mine) and I've since determined water is burning it out, and getting in through the uncovered carb. So I drilled a tiny drainage hole (something like 5/32") so water wouldnt collect, and replaced the magneto and rode it home. Then at home we covered it with a tarp and no longer ride it in the rain or wet areas.

Next clear day I had made some other repairs and modifications and went to test them, and the bike wouldnt fire. It fired intermittently as it did when the other 3 magnetos burned out. But this time... there's no water in the cover, the drainage hole would have drained it enough that it wouldn't touch the coil, and the bike was covered during the rains.

So I'm at a loss here, anything I should check?

EDIT: The thin steel plate under the magnet that separates the magnet from the oil seal is bent, probably from water forcing its way through. I smacked it back down with a screwdriver but it keeps popping up. I'll replace it but I doubt that would cause the issues, but I could be wrong? Green bike runs a stock CDI with a jaguar coil plug boot (the vibrations at high speeds would shake the stock boot off the plug.

Comparative note: The black bike I've been riding for almost 2 years now has been out in the rain, both uncovered, and even riding. Has no air filter either, and never burned out a coil. It runs a jaguar CDI.

I'm having a similar problem with magnetos burning up. It seems to burn up the little wire sticking out of the side of the winding that's soldered to the base metal.
I did ride it once and got caught in a heavy rain. The bike was running fine during the rain, so I motored on a couple more miles until I got to where I was going. When I left that place a couple hours later, the bike started fine. I only made it a couple miles and it just died. I went to check the magneto, and water just DUMPED out of the cover. I thought it had gotten in through the hole where the wires come out, but there is a rubber stopper there and all my seals are good. But the magneto was definitely burnt up. I put a spare magneto on that I "resoldered" that I had with me (this has been an ongoing problem) and it still wouldn't start. So I was lucky enough to catch a bus home and parked it until I got a new magneto.
When I got that in two weeks later, the bike was just completely frozen up. I opened up the clutch side and nasty water DUMPED out of that side too. So I figure that riding in the rain is a definite no-no! The water could have only gotten in through the intake and filled the crankcase and was forced out the seals on both sides into the mag side (which I found immediately) and the clutch side (which sat for two weeks) and had completely rusted everything solid. I was able to break all that loose and got her rolling again. I pulled the piston off and there was some water still down in the crankcase. I put the cylinder back together and got it all the water blown out. I put the new mag on, got it to start up, and it ran for a couple miles and burned the wire on the mag out again. I resoldered that little wire back down to the frame of the mag and she worked again....for a couple more miles. The wire burned up again. I didn't have any wire left to resolder, so I ordered a new mag, played the waiting game, installed and it started right up and ran better than ever...for a couple miles. And that damn wire burned out again. Resoldered wire, ran again, burnt out again. I'm out of mags and I don't want to order any more until I get this sorted out. This problem existed BEFORE the rain incident. What else could it be? The CDI? I always cut off the white wire and heat shrink the wires coming out of the engine, so there's no way the white wire is making anything short out. What does anyone suggest? I even tried one mag that had no white wire, only the blue and black. It ran fine for a few days, then it died too. There's no wires burnt off, and it ohms out ok, but it still wouldn't spark. That was before I tried one of my "resoldered" ones. The resoldered one did work for a couple miles after that one with no white wire, so it can't be the CDI....can it? I'm so confused. HELP!
 

ZipTie

Active Member
Jan 8, 2016
750
48
28
Mpls Mn
Wow, frustrating stories for sure. Water sure seems to be the initial culprit, but does not explain the continued burn outs. My mind is reeling with dumb questions like
A. Is the new mags being installed correctly.
B. Are you buying these from the same source and they are bad from the get go.
C. Is water still in the engine one where and getting on the mag during operation and engine pressure.
D. Is it possible for a bad cdi to somehow short out a mag to melt the thin wire
E. Are you pushing the rpms too hard causing a weird frequency the separates the weak wire
F. Would loosening remounting the motor a tinge over change the vibrations slightly
G. Is chain vibration due to tightness, sprocket defect, housing rubbing causing a weird violent vibration.

At least you know it's the mags so that's a good thing and nothing I've mentioned above will cost anything, its just is where I would start. Is this a Pk style engine?
Seems to me the only thing that can burn out a magneto is a magneto after all its where the juice originates. Say no to moisture,

PS by the way, cooling and rapidly heating cold metal especially aluminum can produce a huge amount of moisture condensation. Store bikes inside - warm them up slower certainly can help.

Zip
 
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ZipTie

Active Member
Jan 8, 2016
750
48
28
Mpls Mn
I just noticed you live in NC with high air humidity, you maybe dealing with mass condensation ( wet mag ) as a wild guess based on a. Bit of experience.