DIY buzz box for magneto timing

[new2mercs]

I found the following link from the Gas Engine Magazine web site really useful:
http://gasengine.farmcollector.com/Gas-Engines/Building-and-Using-a-Magneto-Timer.aspx

It describes how to build a "buzz box" that indicates when your magneto points open to assist in setting the timing. (Mine's way off, which might explain why I haven't been able to get even a pop out of my Mark 58.)

I used an old doorbell buzzer that I had lying around, source unknown but probably Ace Hardware or the like, and a transformer and neon light from Radio Shack. Transformer #273-1380 - ignore the center tap on the secondary; neon light #272-0002 - take it apart and bypass the resistor. I'm running it on two "D" batteries.

I'll post a followup when I've had the chance to reset my timing... probably have the belt off by a tooth.

 

[Fuzzytbay]

Re: DIY buzz box for magneto timing

I just use my DVM on diode test mode.

 

[new2mercs]

Re: DIY buzz box for magneto timing

I dunno, maybe my old Fluke 29 Series II uses a different method for testing diodes: On a Kiekhaefer 4D-5 mag it reads .01-.03 volts while the rotor is moving (slowly) and 0 if it's not; no difference whether the points are open or closed.

What mag are you testing and what are the connection points?

 

[Fuzzytbay]

Re: DIY buzz box for magneto timing

Its possible the flukes you have has a lower voltage than mine, however there is a minimum voltage required to forward bias a diode, and that hasn't changed (so I can't see why it wouldn't work with yours) On mine it has a built in "buzzer" that drops off when the circuit is open, Ie no forward bias on the diode. As for which mags, its worked on my merc 1961 800. on my sleds, 1971 arctic cat 440, 400, and 340. As well as a few others I no longer have.
All with magneto style ignitions.

 

[new2mercs]

Re: DIY buzz box for magneto timing

Looked it up and I believe the max my Fluke will push is 7.2 volts.

Regardless, after setting up the timing with my buzzbox, the motor fired on the first pull! Now I suppose I'll have to keep it... .

 

[Fuzzytbay]

Re: DIY buzz box for magneto timing

The best tool's the one that works for you!