anyone worked on a Cushman OMC 2 cyl engine,,,?

On old tractors that have been converted to 12v, the use the resistor to cut the coil voltage to 6 volts ALL THE TIME... start or run...  I think a 6 volt coil is about 1.5 ohms and a 12 volt coil is 3 ohms...... not sure where the 6 or 60 comes from ???

   According to one of the members of a Forum I been bothering that did venture of a wire at the key that does drop the voltage to the coils when key is turned to start,,then drops out when engine starts,,,? As with purists of every group,,,,he strongly cautioned me to replace the bad resistor with a new one post haste,,,,but,,I also received several suggestions to remove or bypass both resistors for better spark quality and better performing engine,,,,???

BUT,,,,BUT,,,,the best news of the day is,,,,,,(lets have a drum roll, DIYDAVE,,

  These OMC 2 cylinder engines have a  highly questionable intake piping that includes a rubber " T " that on most Cushmans have deteriated over the years by developing cracks in the rubber almost big enough to poke your finger in the cracks.  (Please no dirty comments here)  Mine was that way, so I been fashioning a replacement from a 1" copper tubing T  that is almost a direct fit to the intake piping ,,but did take many  Installs and removals to get it just right so nothing leaks...... AND FIRED THAT MOTHER UP,,,!!!! Engine runs many wonderfuls and sounds great with NO smoke out the exhaust,,,except

 the dang KEIHIN carburator kept leaking at one of the bolt holes,,? I had opened it up and it was very clean but will pull it tamarrow to check it out  and reset the float level.,,,,,, ps,,,I bypassed both resistors, Steve)

If the coils are original, they're most likely wound to fire at either 4.5v, or 9v.  They'll run at 6v or 12v (respectively) and at 7.3v or 14.4v (when charging), however, they will flow considerably more current doing so.  When used in an 8 or 6 cylinder engine, these coils will operate and survive simply because the more frequent ignition events reduce the coil's total 'dwell time' over a course of an engine rotation, than in a single-cylinder application.

They'll work without ballast resistance, but usually, within a dozen hours of operation or so, they'll overheat and expire.  They'll frequently, but not always burn up contact points... if they're good quality plated points, they'll tough it out.

The other aspect of smaller engine coil design, is vibration.  Small, lightweight air cooled motors with few cylinders shake the bejesus out of components... that's why Kohler K-singles don't last long with an ordinary store-shelf ignition coil, and that's why they wear out strange things like carbeurator float pivots.

Modern electronic ignition solves the dwell-time circumstance by doing all the 'hard' work electronically, and only flowing coil current when necessary.

Lots of marininized setups use a 'resistance wire' rather than a resistor module.  Imagine about 8 feet of flameproof cloth wrapped nichrome wire included in the wiring harness of a boat engine... that's what many did.  nichrome is significantly less willing to carry current than standard copper wire, so they used it instead.  There's still a bypass lead coming from the starter solenoid, so that the coil gets full battery on crank, but release the key and coil current flows through the nichrome.

The giveaway that a coil resistor has failed, is the 'starts but won't run'... as you're cranking, it fires, but as soon as you release the key, it looses spark.

The converse circumstance (poor starting, or no start) is often a weak cranking spark, from the bypass circuit not being operational... it's trying to crank and fire limited spark whilst doing so.

Hay DJ

Please measure the resistance of the coils. It'll probably be low, less than 10 ohms.....

'Points' typically like less than 4 amps through them ,else they pit and burn up.

Once we know the coil ohms, can figure out the resistors you should have ( or at least 'safe' ones ). BTW the ones in purdy colored finned aluminum are much better that the old ceramic logs.

  60 ohms is out of reach for that application.  You probably have a 60 ohm resistor there, but it was either put there in error, or it was supposed to be for some OTHER purpose (like powering a temperature gauge, fuel level, or oil pressure circuit).

 BINGO,,,,!!!  Hey Dave Kamp,,,Me thinks that is exactly what has happened here,,,whether the PO thought the previous resistor was bad or whatever,,and just installed one from who knows where is very likely,,,prolly what I would of done in a pinch,,,SO, maybe the resistor that is in there now (bypassed) is prolly a 6.0 instead of a 60,,,,???