Mark 20 with bendix ign problem

[Doug Wilson]

I have a KE7 doing the same thing after I pulled it apart to change the crank seals and lower bearing. Tried the ground wire, will go back and check the points and ignition again. Got the pop and kick back when I reversed the plug wires too.

Doug

how is it motors multiply when the garage lights get
turned off?

[jerry-ahrens]

I’ve seen one of those coils that was defective right out of the box. How about condensers? Every one of the old original condensers [out of a Bendix mag] that I’ve tested on my Stevens machine has been bad. Just a couple idea’s for you anyway…

[mrb]

I cked the condensers today they are the orginals and the ck good on my merc o tronic no leakage and passed the microfarad test .15-.21 mine are .22
close enough . is there another test that i missed Mark

[billw]

Every Bendix condenser I have ever tested on my Stevens machine has been bad, too. It’s the leakage test that gets them every time. You HAVE to have new condensers. Also, as has been said, there are a bunch of things to chase on these mags. They often will run okay with the spark plug gap at .010. Before you scoff, just try it……It can’t hurt a thing.

Long live American manufacturing!

[mrb]

Thanks for the reply again on the Merc o Tronic it has a leakage test for condenser it cks good
Your Right I goffed at that .010 spark plug gap but I will try it thats easy enough Thanks

[jeff-register]

Have you checked your capacitors under a load test? Bad caps = weak spark too. Set the points at wide open throttle position then check gap at 50% advanced. This will show out of round mag plate. Have seen a Mark 25 using Honda 350 motorcycle coils using a battery & worked well too.
Remember to use the Honda cap too for a matched system.

[Dan Smith]

You can test the polarity of these coils to make sure you have them wired correctly as you can hook them up backwards and the motor will still run, just with weaker spark.

I’ve always hooked mine up with no running issues. Red to ground and black to points.

to find out if Bendix wires are installed correct:
Use only an Analog volt meter to check this polarity:
Put the positive wire to the block and the negative wire to the spark plug wire–turn engine over- it the the
meter moves positive wires are correct.–it the meter moves negative–switch the two wires and test
again.

[mrb]

so my question is how do we know what the engine is set up for positive or negative earth . I have put a volt meter on 20 volt scale positive to block and negative to plug wire and the needle swings both ways so I still dont know if its wired correctly. back when this motor was built they used alot of positive ground systems I have hooked the red wire to the points and blk wire to grd. The spark jumps a 100000 gap .

Why then do we worry about coil polarity? Because the spark plugs do care which way the electrons are flowing in the high tension circuit. The spark plug has a thermally insulated center electrode (surrounded by ceramic). With engine running the center electrode runs substantially hotter than the exposed end electrode. Design of the ceramic insulator determines how hot the center electrode will run, leading to the designation of hotter or colder spark plugs. As electrons go, they love to jump away from a hot surface and fly toward a colder surface, so it is easier to drive them from hot to cold rather than from cold to hot. End result is a difference of 15 to 30 percent in voltage required to make spark "initially" jump the gap on the plug depending on which way it is going. So the spark plug prefers to see a voltage potential that is negative on the center electrode and positive on the end electrode for the very first hop of the spark.

[slim60]

Points are critical. Take them apart and clean with acetone. I use a jewelers file on the points. Then polish with 600 grit to a shine. Never let them get wet by revving the motor in the test tank. You probably know this but I learned the hard way. Just my 2 cents. The experts here have more experience.

[jerry-ahrens]

Something else to consider about condensers, if they are weak, you will have excessive arcing across the points. This will quickly burn up the points. Bendix points are in short supply, so why risk it? In my mind, if I take the time to pull a flywheel and replace coils, it’s crazy not to go ahead and replace the condensers at the same time. When I get to the shop later today, I’ll check a new Bendix condenser to see what it shows. When you perform a leakage test, does the needle on the MercoTronic quickly fall back to zero after the condenser discharges? If not, it’s leaking.

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