1982 Honda ATC 70 No Spark

[JRMN]

Hey guys, I've replaced the oil, rebuilt the carb, installed new ignition coil, replaced points and condenser in my 82 ATC70. It still won't start. Originally before I replaced the points and condenser I thought I was getting a a faint spark, but now I am not getting anything. I removed all the wires, grounded my tester to the rear grab bar (this and the handle bars seem to be the only spot that is grounded) and connected the other end to the black primary (low-tension) wire coming from the engine. The light does flicker when I pull the recoil starter. Leaving the ignition switch disconnected (all it really is is a kill switch anyway), I then connected signal wire back to the ignition coil with the tester also connected to the primary wire. The light on the tester doesn't come on. I've also tested the secondary (high-tension) wire and ground with the tester and the light doesn't coming on. Seems as soon as I connect the ignition coil I stop getting a signal from the primary wire from the engine. I haven't checked the cam timing. I think it might be the ignition coil.

When inspecting the ignition coil is it supposed to be attached or detached from the frame? In the manual it's attached. These are the results from my ignition coil which is currently detached.

With the multimeter dial set to measure "200 Ohms" I get 0.7 resistance between the ignition coil primary terminal and ground. The service manual says it's supposed to be between 1.35-1.65 ohms.

With the multimeter dial set to measure "20K" I get 4.73 resistance between the ignition coil primary terminal and plug cap (secondary terminal), which is 4,730 Ohms. The service manual says it's supposed to be between 7.65 - 9.35 ohms.

Is this normal, what am I missing?

[treewheels]

What kind of voltage is the stator putting out? I would work forward from the stator rather than backwards from the coil hope this helps

[JRMN]

Sounds like a good idea. How do I test the voltage and what is the voltage supposed to be? Do I disconnect everything and test the black primary wire coming from the engine and ground?

[JRMN]

What's the voltage supposed to be for the ATC70 6v or 12v? I just found out that the one I got off eBay is 6v.

[YTZ drew]

The point gap is pretty sensitive on the ATC70. Did you eyeball it or use a feeler gauge? I have been guilty of eyeballing the point gap many times, and I've found that sometimes the calibration of my eye is a bit off. As far as the coil resistance, those numbers aren't completely out of whack, I've seen very similar numbers on bikes I've built and they've run fine.

[JRMN]

I used a feeler gauge. I am going to pull the engine again this weekend. Can anyone tell me how to tell the voltage and isn't it AC? Oh and am I supposed to be getting continuity between the primary wire and the coil mounting bar? Thanks

[YTZ drew]

Primary wire should have continuity to the mounting bar/bolts. I assumed that was how you got the primary resistance reading? Voltage output from the mag should be AC, and in theory its a 6 volt system, but the voltage will vary with engine speed, and the readings will be different with coil connected vs. disconnected. Is it an original Honda coil? I used an early snowmobile coil on an atc70 once with good results, but it has to be a coil designed for a points ignition system (not cdi). Also, what's this thing got for a plug cap? The last 3 oem Honda/NGK style (hard bakelite-plastic ones with the screw to bite into the wire) that I tested were bad. They should have about 5K ohms, and I was reading almost double.

[JRMN]

Yes I got the resistance between the primary and the mount bar of the coil. This is the coil I have. After contacting them yesterday and asked about 12v vs 6v I want to say they changed the description because I don't remember it saying anything about 12v listing and now it does.

[fastatc70]

Also during your testing remove the kill switch from the circuit. I have had a couple of bad kill switches. Some times it would work and other times it didn't. Disconnect it to take it out of the equation.

[wonderboy]

I don't think using a test light is the proper way to test for spark, at least not the way you are doing it. A test light is really for testing for steady voltage on wires, not the miliseconds long pulse for a spark plug.

I think your issue may just be point gap (point timing). The feeler gauge just gets you in the ballpark. To truly set the point gap (timing) you need to make a light bulb setup that shows when the point gap is open and closed. Your test light can work. Basically, you need to use a 6 volt or 12 volt battery to power your test light. ground the test light through the wire coming from the points (battery must be grounded to the motor).

Then with the flywheel cover removed, rotate the flywheel and watch the light. The light will go from bright to dim (or vice-versa) when the points open (or close). THe key is you look for the point at which the points switch by a change in the light. If it isn't right, you use a large flat blade screwdriver the adjust the point gap. There is a slot feature cast into the points backing plate that allows you to very precisely adjust the gap either way. You do want to slightly loosen the point set screw so that you can adjust them, but not too loose that the points will slip by themselves.

If you aren't seeing the light bulb change brightness, then your points aren't switching and you will never get spark. If the light goes completely off, then your condensor is bad.

Some more reading for you:
http://www.3wheelerworld.com/showthr...-atc-70-points

I had a thread with pictures over on 3wheeler.org showing pictures, but that site doesn't seem to be working. If I can find the original pictures, I'll post them up here to give you a better idea of what I'm talking about here.

Are you sure about your reading on the multi-meter when set to the 20k setting? For a sanity check, leave it at that setting and check the other circuit what was 0.7 ohms and see if your reading was really 4.73k ohms or just 4.73 ohms. Out of curiosity, what meter are you using (Fluke, Harbor Freight, etc?). If your reading are accurate, then you probably have identified the issues. However, I wouldn't trust a low cost meter for these types of meaurements, it is more for a sanity check (gross resistance measurements).

Also, the coil has to be grounded to function, so make sure the metal where it touches the frame is clean.

[JRMN]

Thanks for the feedback guys I really appreciate your help. I tried replying earlier from a mobile device and it said something about approval.

@fastatc70, I tried with and without the kill switch connected.

@wonderboy, when I set my points I did use a test light and a battery setup. The light flickered or went dim when the flywheel hit the F mark. Oh and I have used two different multimeters. The 11 function multimeter from Harbor Freight and a wavetek meterman 320b. Maybe it's a grounding issue with my frame because I've tried using it to set my points but it wouldn't work. Not sure what' it called but I had to use the area next to neutral indicator shaft. It has a yellow and green wire going to it that coming from the stators.

[wonderboy]

Sorry I misunderstood how you were using the test light. Sounds like you did exactly right to get your point timing correct. If your plug cap to primary terminal resistance is that far off (measured ~ 4k and it should be around 7 - 9) then that seems to be a big problem.

Check the plug cap. Sometimes they get replaced with the style that you can unscrew from the wire. If this is the case, then unscrew the plug cap from the end of the wire, cut a 1/2" off of the wire, then screw the plug cap back on. It could be that the connection is corroded there.

EDIT: Forget the last bit above. I think the book is confusing. I think your Secondary resistance (plug cap to terminal) is supposed to be 7.65 - 9.35 Kohms. In the service manual they show in the front of the electrical section (Page 13-1) the values are Kohms. In the body of the manual where they tell you to measure, they specify just ohms (not K ohms). I think Kohms sounds more appropriate. Bottom line, your coil measures off a bit, but not an order of magnitude off, so I think it may be something else.

[JRMN]

Ok guys, i pulled the engine and I am now getting spark. It's was the ignition coil. My front fender is touching or very close to the front of my engine. So before I put the engine back on, I am going bend the frame back straight. I will report back and let you all know if i get it started. Thanks for all your help.

[shane58panhead1]

In your first post you said you already changed the coil, right? I have a 1980 atc 70 & it kinda sounds like what i'm going through. It wasn't getting spark when I got it, bought new coil, and still nothing. then goofing off , found out I'll get spark with a nail shoved in the plug boot, even the wire without the boot screwed on will spark. Pulled the magneto & stator out they look a little rough, but I'm getting nothing with a plug. And yes its a new plug. Anyone have any ideas?

[YTZ drew]

Plug caps usually have 5,000 ohm resistors in them, and I've seen them go open/develop high resistance. Also, are you running a C7HSA or a cR7hsa spark plug? The extra resistance in an "R" plug plus a bad cap could be to blame. I run non-resistor plugs in anything with points, and "R" plugs in all my CDI bikes.