1980 Honda Express NC50 ignition problem

Jason Majernik /

Moved from General to the repair forum:

I’ve searched the threads and all other sources for a few weeks and have tried everything, but I can’t get spark on my Express. Here’s what I’ve done:

Set the points (correctly, I believe). They were stuck together when I got it, they have been filed, cleaned and set at 0.014”. I can see them open and close when spinning the flywheel.

Changed the spark plug (used a new NGK BPR4HS-it works in another identical Express I own).

Cut back the plug wire and refitted the plug boot.

Changed the battery, although I don’t think it affects the ignition coil.

Tested the coil and condenser, and they all tested ok.

Tested the plug wire. It tested ok.

Did the bulb test as in the manual. The interesting part of this was that the bulb never goes off or dims, whether the points are open or closed. Not sure what to make of this. I’m using a 12v bulb in the test. I don’t know if this matters.

I’ve actually gotten spark for a very brief period twice in about 50 tries.

My points are the version that open and close with the cam. There is one screw that you tighten after adjusting them.

I have been turning the key and run Switch to on with all of these tests, but my bulb test light still comes on, regardless of the key/switch being on or off during all of these tests.

On my points, there are actually 2 wires coming off the points. One black and one black/white. I assume the black goes to ground. The wires coming out of the engine from under the carburetor Are white, yellow and black/white. I cannot see the yellow behind the stator, nor can I see the white wire or where it is connected.

I’d really appreciate any thoughts or advice and I apologize if this has been addressed before. I’m a noob with small engines and this is my first post. I can add pictures (I think).

Below are open and closed points.

5C11AE03-A460-4A39-A921-84924C954924.jpeg
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Re: 1980 Honda Express NC50 ignition problem

Jason Majernik /

Here is a video of my light test.

Timing light test

Re: 1980 Honda Express NC50 ignition problem

The light test is a way to verify that the points are opening and closing and that they are making good contact. You can set your timing that way too. It's known as static timing. Black with white tracer wire is "hot". Solid black goes to ground at the points plate. The other three wires follow through the engine case to the wiring harness via "bullet" connectors. They will be stuffed behind the carb and its air cleaner. Check those connections.

So, how did you test the condensor and high tension coil? There is still the "exciter" coil to check, which is under the flywheel.

Screenshot_2020-07-28-18-38-43.png

Re: 1980 Honda Express NC50 ignition problem

Jason Majernik /

Thanks for responding. This is driving me insane.

I did the coil test as the manual suggests. I don’t know if this was good enough? Obviously not...

Also, shouldn’t the light go off when the points open and therefore the plug fires?

This is the coil test:

CB7F4BF1-0548-499D-BDF5-4B2E5B36713C.png

Re: 1980 Honda Express NC50 ignition problem

Jason Majernik /

I have ordered a new stator and coil from treats. The old stator seemed to have shorts in the ignition (black/white) and white wire that runs to the rectifier (only in the stator harness). I also took off the headlight and found the headlight wiring to be a little wonky as it was a rigged up with an aftermarket headlight in it. The white wire was simply capped. I have fixed all of this with a good lamp from treats as well and corrected that wiring. This moped is costing mean arm and a leg, but I’m obsessed with finding the problem and am in way too deep for this not to work. Any other suggestions? How do I test the kill switch? I’m not great at testing wiring, but I’m learning.

Re: 1980 Honda Express NC50 ignition problem

Jack Rutherford /

I phoned a friend whose cb350 put him thru hell with these issues:

"What’s the test light connected to? One end should be to ground, the other to connection to coil primary. With points closed, current flows through the coil, energizing the secondary, when the points open, the magnetic field in the coil collapses and dumps its current through the secondary to the plug. The light should only come on when points are open, as the battery voltage is now energizing the bulb, not the coil.

If the light is connected correctly, it’s staying on might indicate a short in the coil primary, or a poor connection to the points or the points shorting out against the plate. Use a dmm to check that there is correct voltage when and where you need it.

The cb often had issues with the connector shorting out to the cover or the leaf spring on the points getting pushed back and shorting out on the plate."

Re: 1980 Honda Express NC50 ignition problem

Jason Majernik /

This makes sense. If I’m replacing both the stator (with the points on it) and the coil, this should fix my problems unless there’s a short in the wires leading to the coil from the stator/points. I tested the Black/white wire leading from the coil to the stator (after the stator was removed) and it seems sound. Do I need to test the kill switch wires leading from the handle? (The red kill switch on the right handle). How can I tell if that’s the problem? I’m not sure how to test that connection.

Does this seem like I’m doing the right thing?

Again, thank you for your time.

Re: 1980 Honda Express NC50 ignition problem

if u ground the hot to your points you would be killing the spark.

Re: 1980 Honda Express NC50 ignition problem

Jack Rutherford /

Worry about the kill switch later.

Re: 1980 Honda Express NC50 ignition problem

Jason Majernik /

I suppose one thing at a time. Hopefully getting to it this weekend. My treats are on the way.

Re: 1980 Honda Express NC50 ignition problem

Jason Majernik /

An update: I ordered the new stator ignition. While that was on order, I decided to decarbonize the piston and top end. I took the cylinder off and realized one of the rings was seized to the piston. Ugh. So, I had to order a new piston. I got this one, it looks the same as the old one. I also got new rings for the old one, just in case, but the old piston had some scratches on the side, that I didn’t care for. Hoping the new one works well. I also discovered a local motorcycle shop that would hone the cylinder for me. For $5. Cylinder looks good, especially now. I have a gasket set from treats as well. I had to extend the spark plug wire and used an NGK spark plug wire coupler. Also got a new plug boot. I detected continuity in a section of spark plug wire that I cut off from the old coil, so I spliced that in. Reading 11.7 ohms of resistance from the coil to the boot. I think this is right. I did the light test (gently, because I haven’t put the piston on yet), and I had dimming at the F mark on the flywheel! I might be in business. I want to put the piston on the cylinder before I give it a real spark plug check. Don’t want to mash up the piston arm or the bottom of the engine case. I’ve never put a piston in a cylinder and am somewhat concerned with my ability to do that, but I think I can manage. I’ll put the piston in the cylinder (halfway) and attach the piston arm while the piston is in the jug, and I’ll support the jug on bricks or a block of wood (like in Fred’s guide). I think I’ll get spark. Plan to do this tomorrow. Everything else is set. I painted the tank and it surprisingly had little to no rust and will run new lines on everything including a new petcock. Probably just use premix until I test the oil injection, but it seems solid. I’ve also put on a new headlight and all the wiring and switches seem to work.

Does this seem right? I think I may have it. What do you think? Anything I’m missing?

This is a lot, but I’d appreciate any insight.

Jason

Re: 1980 Honda Express NC50 ignition problem

Jason Majernik /

Holy crap! It worked! Not sure if it was the coil or stator, but I have beautiful blue spark! Thanks, churioz!

Re: 1980 Honda Express NC50 ignition problem

Jack Rutherford /

Sweet!

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