[Kahuna]

I have a slick left impuse magneto 6351, ~300 hours since new.
At the 300 hour mark I was getting a 250rpm mag drop. I pulled it, replaced the points and condensor. The points kit had the points and little plastic cam insert that the points arm rides on to open and close.The cam had worn down quite a bit so I figured I had the culprit. This was my first time inside a magneto.
Ran fine for ~20 hours. Now at under 1800rpm, she barely runs. 2 cyl out of 6 are running. Higher RPMs and it runs fine.
I took it back apart, checked the egap and points, all seems fine. Im scratching my head as to why it runs fine at high rpms, not at all on lower ones.
Coil maybe? my egap technique?
My standard MO for this is to just replace it. But geez these are getting really expensive and it seems the only real wearing part is the points and plastic cam thingy.
Thoughts?
Thanks

 

[Ironflight]

This may or may not help Mike, but I've experienced the "runs OK at High RPM's, hardly at all at Low" condition when my timing was way, way off (this was on an airplane I had a long time ago - the flywheel wasn't indexed properly, and I reinstalled the prop/flywheel 60 degrees off. If I could get it started, it ran at high throttle!). So maybe still a timing problem? Problem with the impulse coupler?

I'll let smarter folks prevail...

 

[Kahuna]

Having had a recent mag problem, I had the pleasure of meeting James (intro thread here) as he came out to my hanger ON A SUNDAY to help me out.


I was having mag issues as noted above. The most frustrating part was the price of replacement. I mean seriously, $900 is INSANE and thats if they get mine as a core.

Though a mutual friend Barefoot Billy, I got a hold of James and he met me at my hanger. He brought is tool bag and I watched a mag guru go to work. First thing he did was test my leads with an expensive looking box. One lead was acting up. WHew! An actual problem found. Excellent!

Next he bagan disassembling the mag while I watched and took notes. These are really simple devices, its the darn parts costs that get high.

First thing he found was the coil spring was not wound properly on the impulse. He asked if I had it apart. ' Uhhh. Yep that was me'. Well I had not wound the impulse spring enough to make it snap through in a snappy manor, enough to produce spark. Hmm. Excellent. Another problem found.

He continued on with disassembly. I took more notes. He tested the coil, gaps, this and that. He felt all was in order but asked if I wanted it bench tested. I said 'you bet', and off we went to his shop about 30 minutes away.

It was facinating to see his tools of the trade. A very cool machinist made bench testing unit that spun the mag whilst you watches the sparks . It was pretty neat. Tested both the impulse coupler and the mag. I just love tools to acomplish things. His were custom made.

He deemed my mag ready for service. He told me $75. I said no way. You get a hundred for coming out to my hanger on a Sunday, on a Holiday weekend, and for giving me much needed training. Im no longer scared of that darn mag thing anymore. I feel confident I can now do routine maintenance and even better, I have a guy in the area that actually services these things rountinely.

It was fun and like going to a slick mag class with 1:1 teaching.

James, thanks for treating me so well and enduring my endless questions.

Mag installed and drumroll please... IT WORKS. Saved me $800 bucks and Im much smarter and probably more dangerous than before.

Thanks James.

 

[Joel]

Hey, good news, Mike, and thanks for sharing. Now I know more about mags too, although I have had a fondness for electronic ignitions for over 40 years.

Caveat for non-believers, this is no place for cutting corners on quality, I have had failures before in a Porsche 912, so be cautious.

 

[az_gila]

For others...

...
First thing he found was the coil spring was not wound properly on the impulse. He asked if I had it apart. ' Uhhh. Yep that was me'. Well I had not wound the impulse spring enough to make it snap through in a snappy manor, enough to produce spark. Hmm. Excellent. Another problem found.
....

...who want to take the impulse spring apart - this video from Sacramento Sky Ranch might help...

http://www.youtube.com/watch?v=FAcIThVWAeQ

 

[Geico266]

Excellent video Gil, thanks.

 

[chuckwn]

So what was the actual problem?

Kahuna,

So what was the actual problem? One bad lead? Impulse spring? and ?

Just curious,

Chuck

 

[Kahuna]

Kahuna,

So what was the actual problem? One bad lead? Impulse spring? and ?

Just curious,

Chuck

All of the above and my egap was slightly off.
I used eyeball with the tool. The corect method is an ohm meter with the tool.

 

[rv8guy]

great post Kahuna

thanks

 

[IowaRV9Dreamer]

For those that don't want to DIY their mags, I recommend Magneto ER in Searcy AL. Great quality repair work at affordable price. Not affiliated, but a happy customer.

 

[frangatang]

Doe this apply to slicks as well?

 

[pierre smith]

Errrr, Frang...

...reread the first sentnce of the first post

Best,

 

[frangatang]

Thanks, just read the first entry and wish l hadnt parted with $800
for a new impulse from spruce!

 

[SirKnight]

Having had a recent mag problem, I had the pleasure of meeting James (intro thread here) as he came out to my hanger ON A SUNDAY to help me out.


I was having mag issues as noted above. The most frustrating part was the price of replacement. I mean seriously, $900 is INSANE and thats if they get mine as a core.

Though a mutual friend Barefoot Billy, I got a hold of James and he met me at my hanger. He brought is tool bag and I watched a mag guru go to work. First thing he did was test my leads with an expensive looking box. One lead was acting up. WHew! An actual problem found. Excellent!

Next he bagan disassembling the mag while I watched and took notes. These are really simple devices, its the darn parts costs that get high.

First thing he found was the coil spring was not wound properly on the impulse. He asked if I had it apart. ' Uhhh. Yep that was me'. Well I had not wound the impulse spring enough to make it snap through in a snappy manor, enough to produce spark. Hmm. Excellent. Another problem found.

He continued on with disassembly. I took more notes. He tested the coil, gaps, this and that. He felt all was in order but asked if I wanted it bench tested. I said 'you bet', and off we went to his shop about 30 minutes away.

It was facinating to see his tools of the trade. A very cool machinist made bench testing unit that spun the mag whilst you watches the sparks . It was pretty neat. Tested both the impulse coupler and the mag. I just love tools to acomplish things. His were custom made.

He deemed my mag ready for service. He told me $75. I said no way. You get a hundred for coming out to my hanger on a Sunday, on a Holiday weekend, and for giving me much needed training. Im no longer scared of that darn mag thing anymore. I feel confident I can now do routine maintenance and even better, I have a guy in the area that actually services these things rountinely.

It was fun and like going to a slick mag class with 1:1 teaching.

James, thanks for treating me so well and enduring my endless questions.

Mag installed and drumroll please... IT WORKS. Saved me $800 bucks and Im much smarter and probably more dangerous than before.

Thanks James.

Anytime brother, Keep turning fuel into noise