The Hodaka Club Forum

Hey guys need some expert advice as I'm pretty new to hodakas. I've been fighting a spark issues for a while now. I'm trying to figure out if it's something in the wiring harness or something mechanical. I currently measure 2-3V leaving the magneto, is this enough? If not then it's either the ignition coil or harness. One note about the harness is that the switch is broken so don't really know whats on or off. There for if you know what wires need to be jumped to have a constant on just to test spark it would be greatly appreciated. I've attached a picture of the wiring diagram for reference. Thanks in advance!

Here is the same wiring diagram with all the extraneous bits removed. All that is left is the ignition circuit - without the main switch.
Ed

Serendipity! I'm in the process of putting together a stripped down Ace 100 for a play bike and that is exactly the ignition system I had in mind! Thanks Captain!!

Bullfrog wrote:Here is the same wiring diagram with all the extraneous bits removed. All that is left is the ignition circuit - without the main switch.

tech_Acewir IgnitionOnly.jpg

Ed

Ed, from this picture would you have to jump the black and blue and the green and yellow coming from the magneto in order to have complete circuits or should it fire with the 4 prong connector unplugged just like you have it?

tyjolson wrote:

Bullfrog wrote:Here is the same wiring diagram with all the extraneous bits removed. All that is left is the ignition circuit - without the main switch.

tech_Acewir IgnitionOnly.jpg

Ed

Ed, from this picture would you have to jump the black and blue and the green and yellow coming from the magneto in order to have complete circuits or should it fire with the 4 prong connector unplugged just like you have it?

Please allow me... Yes.. just as Ed has illustrated. The blue and black wires from the magneto to secondary coil is all that is need to get a spark, (assuming the magneto is functioning correctly).

Keep in mind that if you try to start the engine this way, it will start; but you will have you have no way of shutting it off. You'll need to provide a way to short the black wire to ground, i.e. the frame if you wanted to test it to start.

Roger

Thanks especially for adding that last paragraph Roger. I should have mentioned the need for some way of shutting the engine down.
Ed

I always have a screwdriver in the pocket as even a kill button can fail. -------Clarence

Clarence, it might be good to describe just how you use that screw driver to shut down an engine if the kill button fails.
Ed

With the air filter removed, open the throttle wide so the slide is up and then shove the screwdriver in the Venturi. Stops immediately. Not recommended for future use of the bike.

Whatta you do, Clarence? Pry the plug wire off with the screwdriver?

Thanks everyone for the help but no need for kill switch as no fuel is being introduced at the moment just trying to get spark from the spark plug when grounding it outside of the combustion chamber! Is 2-3V enough coming out of the magneto at the connector just before the coil?

For what it's worth, the Hodaka Shop Manual says voltage exiting the exciting coil should be 8 volts at 2500 rpm. If you're getting 2 or 3 volts at some kick start speed that may be fine.
I've found that rotating the flywheel by hand back and forth will provide a spark at the plug. Just line the flywheel up around the timing marks and twist the flywheel back and forth.
Ignition coil should check around 5000 ohms secondary resistance, half to two ohms primary resistance.
Hope this helps.

Kinda like a gun Clarence, more likely to stab yourself when you fall than to stop a runaway Hodaka from getting you. I guess if it was a phillips you could disassemble the engine to stop it. Just thinking'.

Maxie, always helpful-----

Got a call from a friend the other day, he was having a no spark issue on an Ace motor. Rebuilt stator assembly, known good coil, new pts and cond. Timing set correctly. I had him run a wire from the coil mounting bolt to a bolt on the engine as a secondary ground wire. Got spark then and had it running shortly afterward.

Al, thank you that was very useful. I was able to measure 2 ohms on the primary but wasn't able to get a reading on the sdconday. I didn't have a time to really dive into but will look further in the next couple days.

A bit of a long shot, but if you find secondary resistance to be "infinity" it may be the spark plug cap to high tension wire connection.

My Ace had this type of plug cap.

I don't use it anymore, but it does come apart. And the "sharp tip" was in rather corroded.

Al that actually ended up being sort of the issue surprisingly. The spark plug wire broke at the tip so I just cut it off and moved the cap down alittle bit and got 5.1k ohms in the secondary. Still no spark from the Champion J4C spark plug though...now at the next hurdle

Longer long shot... Try a known good plug you've seen spark. Maybe one out of your mower. If it's running.....

Past experience in the motorcycle business taught that 9 out of 10 times, a no-spark situation is a bad spark plug. Champions were one of the worst of the times. Stuff from the past but I have a good memory. NGKs are the hot set-up for old two-strokes. Always the suspect is the plug even if new.

Maxie

This all goes back to the useful trouble shooting adage of replacing things, one at a time, with 'known good' parts to isolate problems.

This article may be of help, maybe not. Magnetos are pretty simple things. If you have components in good order this is how it's supposed to work. Maybe there's something here that will shine a light on the trouble.