Topic: CB500K No spark with new Electronic Ignition

[nvts8a]

Hey all, long time lurker and reader. This is the first time I seem to be having some trouble finding an answer to my problem.

Some background, before this summer I'd never worked on a bike before in my life. My buddy fed up with maintaining his non-running CB500K gave it to me and I turned it into a project. So I've made a lot of mistakes and don't mind paying that price as long as I learned something. It's been fun. I got the thing running, with the help of forums, YouTube, the Clymer, and 4into1.com. And I've been riding it around, getting it fixed up.

A couple weeks ago, I thought it'd be fun to install an Electronic Ignition after I saw it in browsing on 4into1. Knowing nothing of them, I bought up the one I saw in passing, which was probably a big mistake considering I can't even find the make of it now and a lot of recommendations and videos are for the Dynatek or others. But it's this one from 4into1: https://4into1.com/electronic-ignition-honda-cb500k-550-750/. It looks similar to a Kokusan, bare board covered in a clear film, same instructions too.

So I've been following the instructions and everything seemed pretty easy. Felt confident in the setup, turned the key, flipped it to run, pressed the starter, and the engine just turned over and over. No combustion, just revving.  The coils, caps, and plugs are brand new. The bike was just running well enough with points so I know it at least should be trying to fire.

The LED while I was setting it up would turn on. Took a plug out, tried to see it spark, no go. Using a multi meter I confirmed, I was getting 12v in, but never got a voltage from blue or yellow when I'd turn the engine with a wrench. So it seems pretty obvious, power isn't going to the coils. Before I try and beg to return the thing well out of the return window I wanted to post here and see if anyone had any advice or troubleshooting I could try to see if could get it going.

Thanks in advance,
Steve


Reference:
'72 CB500K
Electronic Ignition: https://4into1.com/electronic-ignition-honda-cb500k-550-750/
Coils + Caps: https://4into1.com/ignition-coils-and-caps-honda-cb350f-400f-500-550/
Plugs: https://4into1.com/ngk-d7ea-spark-plug/

[TwoTired]

Simple things. Off-run-Off switch to run.
Check for 12 V on the blk/wht wires to coils.

Check for timing being 180 degrees out.

I don't know what you have for electronic ignition.  But, most are just points replacement things.  The points switch ground on/off to the coils.  Grounding charges the coils.  Ungrounding allows them to spark the plugs. If coils have power (12V) then grounding either yellow or blue wires should make that coil spark when ground is removed.  For points, the condenser (capacitor) helps form the spark.  The electronic unit shouldn't need that.

Points replacement unit does NOT provide power to the coils, it just enables function that through grounding.

IF you have 12v going to the coils and never see volts on blue or yellow, the elec unit isn't ungrounding the coils. =no spark.

By what method does the unit see crank position?  Was the points cam replaced with something else?  Please describe it.  That device should tell the unit when to release the ground for that coil.

Cheers,

[Kenzo1979]

If it is a good unit, and you didn’t space out and forget to put your emergency stop switch into run mode before you tried to turn it over, it’s probably the other thing that TwoTired mentioned - you put the new cam on 180 degrees out of alignment.  If you’re unfamiliar with this, it’s an easy mistake to make.  Here’s a good video on the original function of the stock advance unit. It explains the 180 degrees out thing at about 4:45 minutes in.

https://youtu.be/NWmeU3OALfU


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[Kenzo1979]

Not sure it would still be considered a cam, not in the sense that it would be mechanicallly touching anything, but it would replace the cam from the original unit and it would function the same way; there will be a high point on the rotor that will trigger each sensor as it goes around.  Anyway it’s very possible that you just need to pop that back out, rotate it half a turn and pop it back in. 


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[nvts8a]

Simple things. Off-run-Off switch to run.
Check for 12 V on the blk/wht wires to coils.

Check for timing being 180 degrees out.

I don't know what you have for electronic ignition.  But, most are just points replacement things.  The points switch ground on/off to the coils.  Grounding charges the coils.  Ungrounding allows them to spark the plugs. If coils have power (12V) then grounding either yellow or blue wires should make that coil spark when ground is removed.  For points, the condenser (capacitor) helps form the spark.  The electronic unit shouldn't need that.

Points replacement unit does NOT provide power to the coils, it just enables function that through grounding.

IF you have 12v going to the coils and never see volts on blue or yellow, the elec unit isn't ungrounding the coils. =no spark.

By what method does the unit see crank position?  Was the points cam replaced with something else?  Please describe it.  That device should tell the unit when to release the ground for that coil.

Cheers,

Thanks a ton, that was great information. Still learning, so I'm still filling in tiny tid bits of the how and why everything works. Makes a lot more sense than my assumption that it was supplying power, but actually just grounding it.

So I'm gonna head back out after work and just double check that the coils are getting 12v. And I have confirmed blue/yellow + black/yellow aren't getting a voltage as I rotate the crankshaft clockwise 360°+ around. I can take a vid after work too if needed.

The unit sees the crank position via an item they call an aluminum rotor with magnets on it, as far as I can tell. Here's the instructions the unit came with that includes rough photos of the unit and the rotor: https://images.cmsnl.com/shop_media/1/3/6/6/D1301_IgnitionTrigger.pdf

If it is a good unit, and you didn’t space out and forget to put your emergency stop switch into run mode before you tried to turn it over, it’s probably the other thing that TwoTired mentioned - you put the new cam on 180 degrees out of alignment.  If you’re unfamiliar with this, it’s an easy mistake to make.  Here’s a good video on the original function of the stock advance unit. It explains the 180 degrees out thing at about 4:45 minutes in.

https://youtu.be/NWmeU3OALfU


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Not sure it would still be considered a cam, not in the sense that it would be mechanicallly touching anything, but it would replace the cam from the original unit and it would function the same way; there will be a high point on the rotor that will trigger each sensor as it goes around.  Anyway it’s very possible that you just need to pop that back out, rotate it half a turn and pop it back in. 


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Thanks for the reply! I was instructed to place the rotor on the spark advancer with the dot on the rotor pointing to the 14TF on the spark advancer, I believe I did that, I double checked a while back. But I'm also gonna triple check when I get home too, because the dot is on the underside of the rotor facing the spark advancer  . If it is in the correct position per the instructions, I imagine I can try rotating it anyway and see if somewhere down the line they changed the unit but didn't update the instructions?

[nvts8a]

Just an update here. Spent some time over the weekend tinkering with it per suggestions and there was no go. Rotated the rotor 180° to see if it would do anything, but it was nothing. Still no spark, still no voltage. Tried an old fashion timing light attached to ground + the blue wire running to the electric ignition with the coils on and didn't get anything.

Thanks for all the help! Unless there's any other obvious suggestions I might just have a bad unit? Electronics are like that sometimes.

[Kenzo1979]

At the very least you can verify  by putting the old ignition plate in, I’m guessing it was stock style points and condensers. Then see if you have anything.


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[Bodi]

This "no voltage" thing...
If everything is connected, you should have +12 volts on the blue and yellow wires almost all through a crank rotation. That voltage comes from (through?) the coils. The ignition unit likely works by opening it's ground connection to the coils when the aluminum rotor magnet is beside the ignition module pickups - the pickups should be fairly obvious components on the board, they will be positioned close to the rotor when it's installed. No other components on the board will be the same as these two.
Power for the coils comes through the ignition and kill switches to one of the two wires on each coil, the other wires go to the ignition via the blue and yellow wires.

If you get no spark ever, that's not the 180 out problem... that still makes sparks but they happen at the wrong time.

So if you measure no voltage with the ignition connected and switched on, try disconnecting a wire (blue or yellow) from the ignition and measure its voltage. If you still have no volts on that wire from the coil, there's a harness or switch problem.
You mentioned new coils I think, did you connect them to ground? You do seem confused about how the ignition system works if you expect voltage from the module.
If you do get voltage - if the module is powered (you say the LED lights up so it must be) then either the module is bad or the magnet is not positioned correctly.