Pulse generator help!!!!

[Dgonzo]

So I recently picked up my first 3 wheeler for a whopping 60 bucks!!! It’s a 1984 110, the guy I bought it from said it ran but the carburetor was leaking. I took his word for it for 60 bucks I didn’t really care. I did have compression when before I bought it. Anyways I am having trouble getting spark. I’ve replaced the stator, coil, spark plug, cdi box. The only thing left is the pulse generator. I checked the resistance on the blue/yellow and green wires and I am getting 90 ohms. Is this bad? And what is the ohms reading supposed to be? Any help would greatly be appreciated!

[Lrequa92]

I have a 1985 125m which in my manual the spec says 90 ohms for the pulse generator so it sounds like it is good but it may be slightly different for the 110.

[Dgonzo]

I checked mine and I got 90 ohms as well. Anybody know if this year 110 needs a resistor on the spark plug. I got one and it only had the threaded end on it which was a NGK-DR8HS. Could this not having the resistor on it cause it not to spark?

[DAM shop]

Check all your wiring for breaks also check your coil wire, you might have to snip off a 1/4" of wire and screw your cap back on.. also check your cap.
More times than not it's a break in a wire somewhere..

[ps2fixer]

I spy blind parts replacing, did you test any of the orig parts, or the replacement parts, maybe you fixed the problem, but introduced another bad part?

I don't have the greatest manual for the 84 atc110, but here's some numbers. I could cross ref to another machine's factory service manual if anything seems weird or off.

Coil:
terminal to ground - 4.1ohms
spark plug wire to ground - 1.8ohms (it says to remove the spark lead which by the photos appears to be the spark plug 90 degree cap)

Excitor Coil:
black/red to ground 110-400ohms

Pulse Generator:
blue/yellow to ground (green) 90ohms +/- 10%
Gap between rotor and generator should be 0.3-0.4mm

Also should note that the kill switch shorts the black wire (most other machines used black/white wire) to ground for engine kill, disconnecting it and checking if the wire is shorted to ground on both harness and handle bar switch side might tell a story. Switch side you'll have to test to the green wire, or leave the green wire hooked up if possible.

Also, you can't rule out the wire harness, they are getting old and a lot are brittle from age & sun rot. If the harness isn't flexible like rubber, it's showing it's age and could have breaks inside. Might be a bit of a chore, but testing for connection between each spot of the harness to cdi (the central brain, basically all wires end up here for ignition system), you can test if you have a bad wire. Also note corrosion on the terminals, they should be clean looking, not pitted, green, or white. The CDI connector is a sealed style, so it should be fine, but the engine side of connectors and such might not be so nice.

Should also note, service manual says 82+ atc110 should have a NGK DR8ES-L spark plug with 0.6-0.7mm (0.024-0.028in) gap, if the new plug you put in it isn't that, go buy the right plug, don't settle for other brands, Japanese engines almost always run best with NGK or Denso as their service manuals call for.

For a step further, compression should be 175psi +/- 22psi, min allowed being 128psi

Finally, here's a wire diagram for the 81 atc110, not the exact same, but should be very similar.


Good luck troubleshooting the issue, let us know what you find.

[Dgonzo]

Thanks everyone! I am determined to get this this going. I will be working on it this weekend and hopefully I can make some progress on this thing.

[Dgonzo]

I didn’t test anything before I bought the new stuff. I kind of went with what needed to be replaced as far as what I thought was the problem. But yeah I might of made the issue worse! I kept all the old parts just in case and will test the new to the old and see what is tells me.

[ps2fixer]

That's what I was guessing. hopefully it's something simple overlooked like the kill switch was off. Good luck!

[deejaycee_2000]

I have the same problem with my 250ES, all the checks is 100% on spec but no spark, the only thing is a break in a wire somewhere, this happens from vibration over the years ... I am yet to find it, but eventually I will! Unfortunately the 250ES have ALOT of wire!

[ps2fixer]

I have the same problem with my 250ES, all the checks is 100% on spec but no spark, the only thing is a break in a wire somewhere, this happens from vibration over the years ... I am yet to find it, but eventually I will! Unfortunately the 250ES have ALOT of wire!

My suggestion is similar as to the atc110, but there are a lot of wires, so you'd want to narrow down the search. Assuming your machine is a 1985 since that's the most common (86-87 should be similar anyway)

Disconnect handle bar switch and test black/white wire to green with kill switch to on, should be no connection. Test the same wires on the harness side with ignition switch to on, again should be no connection. If there is a connection, the CDI is being signaled to not spark and you'll need to test the ignition switch or kill switch directly and replace as needed (unlikely).

Next I'd pull the CDI out for probing. Green wire to clean engine ground, or the frame ground location should have solid connection. Grounds are pretty critical so never hurts to validate it's good. All solid green wires should be the same connection at any point in the harness.

The big red has a neutral and reverse safety switches. With a battery and key on and machine in neutral, the neutral light should light up. If it does not, either there's a poor connection, bad safety switch, or burnt bulb. Both safety switches connect to ground with enabled (aka when in neutral, neutral switch connects to engine ground). I suspect this is the likely cause since it's near the bottom of the engine under the little metal cover. I sell replacement sub harnesses for them using plain bullet connectors (no rubber housing around them). If one of the switches test bad, you can buy them from Honda yet. I've had a machine with shifting problems also cause the no spark problem and no neutral light, getting it into neutral gear after disassembly fixed the ignition problem.

Ok, if all tests good by this point then I'm thinking a bad wire or CDI. CDI is easiest at this point if you have a known working one, or can borrow one. I kind of hate to suggest buying a CDI since they can be expensive. Connection quality can play a large factor and could make a good cdi appear bad.

Probe time for the rest of the CDI pins....

Green we tested already
Black/Yellow goes to the coil
Black/Red goes to the alternator area on the engine (bullet connector)
Blue/Yellow & Green/White goes to the pulse generator @ the same general location as the alternator connectors (3 pin connector)
Black/white goes to ignition switch and kill switch, generally when the wire fails, there won't be a connection, which would fail in the can't stop the engine running style.

If everything tests good, might have to go over the individual component tests again to be sure they are in fact good. My bet is the neutral safety switch wire though, most of the machines I've seen had pretty corroded up wires, or the connectors were very loose and made poor connection.

The rest of the wires are for charging, starting, lights, etc and shouldn't effect the ignition system.

I have a 250es service manual if you need any specs.

I almost should build a website with step by step troubleshooting steps and common problems lol.

[DAM shop]

Ps2/Dgonzo

The plug is not a L plug. SPARK PLUG (DR8HS) (NGK) is correct one, the L stands for long and the R stands for resistor on the NGK

[ps2fixer]

I wouldn't doubt the off brand manual I used is wrong that I pulled the info from. Here is a screen shot for a 79 atc110 from a Honda Shop Manual. Seems the DR8HS is a Canadian part number so I included the rest for reference.



Here's the off brand shop manual for reference. Not sure why they claim 82+ atc110's take a different plug. I haven't really messed with 110's so can't really say one way or the other.



Just for giggles, I jumped into a Honda service manual for the atc125m to see if the plug info matches, and it does.

[DAM shop]

Yeah thats all messed up, thats a good way to ruin a piston there. The CDI 110 models run the "R" plug. The points motors both 90 and 110 have the correct plug listed. The 125m plug is correct.

[Dgonzo]

So the DR8ES-L is the incorrect plug for my 1984 110?

[ps2fixer]

I forgot I had some Owner's manuals saved. For an 1982 ATC110 Owner's manual it does state the spark plug is a NGK DR8HS. I'd trust this manual since it is a Honda produced manual. 82+ ATC110's should all be the same, sadly I don't have the exact year of manual. I'd say DAM shop is spot on for the spark plug info.