UPDATE: it runs!! ('83 70 w/ no spark)

[pismorat]

Hey everyone, noob here. I got an ATC 70 for free that needs a lot of work. I went through the carb, mag., points, and all that. I was getting spark to the plug, then I tried to fire it up and it ran for 2 seconds, then died. Now I am not getting any spark. I am wondering if something got fried and if there's any way to test the parts. Points and all still look good. Thanks in advance.

[Unclediezel]

Look carefully at your points again----Hondas eat them for lunch----

Points are basically nothing more than an on/off switch---contact-/-no contact--if you spin the motor while watching the POINTS--there should be a small spark between the contacts as they open and close----They can slam shut unexpectedly---or stay open just the same---

:welcome: to the boards

[pismorat]

I checked the points, they look good. I have the gap set at .014"...the spark plug wire was pulled out when I got it, so I cut the plastic back and re-soldered the wire, the connection still looks good, but I am wondering if the coil could be shot. Any idea how to verify its status? Just wierd that it would start for a sec then loose spark again. Thanks.

[Unclediezel]

Does it have a Resistor type Boot----?--

You can check the coil with an Ohm meter--but it isnt always idiot proof.
There are Specification Sheets at the front of the site
http://www.files.3wheelerworld.com/pdfs/atcspecsreference.pdf

[pismorat]

Just went out to test the wiring...the spark plug wire shows voltage when the engine turns over. I wonder if its not getting enough voltage to fire the plug though. Any thoughts?

[Unclediezel]

How did you test voltage, and where? The spark plug wire is that rubber coated-hi-inductance wire that clips onto the plug-- are you talking about the wire that comes from the points?

[slothminx]

he will be talking about the wire that comes from the points.

The 70's are very picky when it comes to points you will need to play with them quite a bit to make them work properly. Mine would be giving out a voltage from the points but if that voltage is constant and doesnt have the change in it the coil wont function properly. I would check those points again make sure you have all the stuff connected properly to the condensor and the points and try again.

Will

[Unclediezel]

E-Slap for Uncle D--------

If the condenser shorted-- It would cause the same thing---Can you take it out of the circuit and try it again?

[pismorat]

I checked both the wire from the points and the spark plug wire(through the coil). The voltage alternates too as the points open and close. Logic says that it should fire, but it isn't. I even tried a different plug. I had spark during pre-firing and for a few revs of the motor, but something gave out. It has been sitting for 5+ years, but why would it have great spark and then let go the second it starts running? And I think the condensor is hard wired in...

[Unclediezel]

Alternating voltage---Thats what you were lookin for---Coil is possibly burnt----But---First check hondas other pet problem----Loose ground connections at the coil mount. -Especially if its been sitting---

[pismorat]

Well, I am going back to the beginning. I got the wiring diagram off this site, but am a little confused where the wires from the points, condensor, and nuetral safety switch go. They go to a plug on mine, but it was capped and nothing plugged into the other end. I am wondering if something is missing. The black wire goes to the coil, but what about the dark green and green w/red? Thanks.

[danteross77]

Those extra wires come from you lighting coil, should you decide to add a headlight, tail light etc. I believe the light green on goes to your neutral indicator, which was designed to not let the bike start in gear, it will run with it disconnected, the only wire you need from the stator to run is the black wire, it goes to your coil. Honestly it took me about 6 months off and on to get one of these things running right so don't let it get you down, first and foremost I don't care what kind of test you have run, do yourself a favor and buy a new set of points and condensor. I would not attempt to tackle one of these without those 2 things new. They are cheap and easily replaced. I bought a tune up kit for mine off of ebay for $18 delivered. Or you can check with your dealer, the points are $25 alone that way though. As for setting the points, they are really finiky, I read several threads and several books using everything from feeler gauges to matchstick cover to timing lights. To each is on. I finally got it running right just using my eye and watching it open as the timing mark comes around. (after I tryed the other ways)Once I got the first one running, I had all the confidence in the world, and got the parts bike I used to build the other one running just for the heck of it. Now I am looking for a used seat and fender for it.

[pismorat]

Update...it runs!! Ended up being a combination of points being a little out of adjustment and the coil not beign grounded right. Now I'm going to get the wiring set since it was kind of rigged before. It smokes a lot though, so I'm going to tear it down and get new rings for it. Anyone know a good source for parts other than a dealer? Thanks a lot for all your help so far!!!

Doug

[Vealmonkey]

pismorat, Dratv-beatrice cycle, is the best place for things atc 70ish. The have big bore kits, from 85cc up to 110cc. 85-88cc is good and don't forget a nicer cam. You will love this site for the atc70. Happy hunting.