Timing Pony Magneto To Engine?

You don't want much advance on a hand cranked engine. The magneto impulse coupling will retard the timing to about TDC until the engine speeds up.

Are you sure the wires aren't swapped between the cylinders so it is firing the wrong plug?

You don't mention fuel. Since you haven't gotten it started, are the plugs wet, If not, I would say you aren't getting enough fuel into it. I am always amazed how rich the mixture has to be to start our pony motors.

Thanks for the reply! Yes the plugs are wet with gas, and i cant even get it to fire on starting fluid. the motor will periodically fire back through the carb, but this rarely happens. thats when i checked the wires. yes the wires are on correct as well. the #1 piston plug (closest to front of engine) fires first. as far as timing goes, you think the plug firing when the piston is at the top of its stroke is good for these pony motors?

Which magneto do you have? American Bosch or Eisemann. Timing procedure is a little different for either one but both should fire at 25 degrees ahead of top dead center.

Grit,
No, firing at TDC would not be good for a running engine. Burned valves and reduced power and efficiency would be the most likely result. On the other hand, while hand cranking, firing much before TDC would be bad for the person on the crank. The most likely result would be kick back and cursing and swearing😛

That's the function of the magneto impulse coupling, to retard the timing during hand cranking (very low rpm) by cocking and tripping and also to increase the intensity of the spark by causing the magneto rotor to snap forward quickly as the coupling trips. As the engine speeds up, centrifugal weights take the impulse out and the mag fires at a normal advance, as OM says, 25 degrees BTDC.

The fact that you got a spark while watching the connecting rods through a small hole almost certainly means your engine has a functioning impulse magneto. You should hear the impulse coupling thrashing around in the mag as you crank the motor over.

The small pony motor on the D2/D4 doesn't have the impulse mag, and you spin it with a rope to make sure it doesn't kick back and to get a hot spark. The larger pony motors should all have impulse coupling type magnetos because of the difficulty of spinning them rapidly enough like the smaller D2 size.

When you are turning your magneto to time it up before installing it, turn it backwards to get to the mark and it won't cock the impulse coupling. Try to turn it forward and it should begin to wind up and get tough to turn as you approach the mark and not want to stay where you need to leave it while you install it.

OK, reread the post and you have the Bosch mag.
With the mag removed and the distributor plate off rotate the coupling in the opposite direction from drive (direction indicated by arrow on top of the mag. housing). Continue to turn the coupling until the red mark on the coupling lines up with the red mark on the housing and the distributor rotor is in position to fire #1 cylinder. Breaker points should be just beginning to open. Replace the distributor plate and install mag on engine. Flywheel mark should match housing mark.

If the internal parts of the mag are timed right, here's another way to time the mag to pony.

Take the sparkplugs out, turn pony engine until #1 piston has compressed all air out of cylinder and is at TDC. Trip the mag impluse (forward) until you determine which plug wires are #1 and #2. Then one more time, trip mag until #1 has fired, turn the slack out of the impluse and install mag on pony. Install plug wires in the mag and on the plugs. Now hold #2 sparkplug against pony and hold a finger over #2 hole. Turn crank until #2 compresses and is at TDC. #2 sparkplug should fire at the same time as #2 piston reaches TDC.

is the procedure described here the same for a pony in a 955H??

I have a mag problem and getting it checked out, but once returned, i will need to reinstall and get the pony running.. there is a timing mark on the mag gear, but cannot find a mark on the cam gear...

thanks


rod