1980 Sportfire no spark!

[JASONT]

Hello, all! Newbie here. Looking for some advice and assistance. I just picked up an 80 sportfire and am working at getting it going. Previous owner had let sit for a couple years. Pulled tank and carb and disassembled and cleaned. So far so good. Put back together and pulled it over a few times and Nada. Pulled and cleaned all electrical connectors and switches....Fuel I've got, spark not so much. I disconnected the key and kill switches and still nothing. Pulled coil and cleaned connections and reinstalled. Still nothing. Super frustrated because I don't know enough to know where to go from here. I'm thinking replace coil??? Could it be the CDI??? Thanks for any help u can give.

[JDT]

Hello Jason and welcome to the forum.

You may be correct in thinking coil or cdi.
But before you run out and replace the most expensive parts of the ignition system let's eliminate the little and cheap things first.



Pull both spark plugs out of the engine and hook the sparkplug wires back on them. Than lay the plugs on top of the metal shrouding on the engine so they are both in contact with "ground".
(This is very important because if the system is working and the plugs are not grounded when the CDI sparks them the CDI can burn out. It is also much easier to pull the engine over when testing with the plugs out as you have zero compression. And you can pull the engine over much fast without compression.)

You want to isolate the engine from the the rest of the wiring harness by unplugging the harness at the engine connection. This will remove many components such as the key switch, kill switch, tether switch, thottle saftey switch, rpm limiter , ect. This makes it much easier to troubleshoot.
Now pull the rope. Do you have spark?
If you do than you know the problem is in the wiring harness or any of the items mentioned above.
If you do not have any spark there is one more thing to look at before we continue.

On your Sportfire there are two wires that go from the CDI box to the engine connector you just unplugged. One Grey and one Black. On the back of the connector where these two wires go into the plastic look very closely to see if there are any loose strands of wire touching between the grey and black termainals. One single strand of wire bridging these two points and you have shut off the ignition curcuit.

You mentioned that you do not know much about these ignition systems so I am going to assume that you do not have a meter or know how to use one.
Therefore the following is a way to test out everything without these tools. It is lenghty but valid.

Make sure all electrical connectors are plugged in where they are suppose to be. Turn the key switch to "on" and make sure the kill switch is in "run" position.
If your machine has a tach and speedo the following test will even tell you more.

Now dim the lights or turn them off in your shop/garage. Approach the sled, say a hail mary and pull the rope.
The following things should all happen.
You should see spark alternate between the two removed spark plugs.
You should see the tach needle jump up from zero.
The headlight should glow dim for a moment. Same for the taillight and the tach/speedo dial lights.

If you have spark, even very weak spark, then you know something is trying to work. That is why it is nice to do this under low light condtions.
If you have spark on only one plug even that tells you something.

If none of the light bulbs glow, even a little, again you know more than when you started.
If a couple of the bulbs glow and a couple do nothing again you will have learned something.

If no lights glow at all than you either have a pile of burned out lights or you have a problem with your lighting curcuit.
Things to look at here would be a bad voltage regulator. If it fails it will toast every bulb on the sled.
A bad flywheel will cause the lighting curcuit to not work AND THE IGNITION CURCUIT to be dead.
A bad lighting coil will also cause a no lights situation but has nothing to do with the ignition curcuit.
If even only one bulb glows you know that your flywheel, lighting coil and at least some of your chassis wiring harness is good.
The only thing in common between ignition and lighting curcuits is the flywheel and ground.

Aw yes, ground. The ground curcuit is critical for anything electrical to function on the machine. Ground consists of the metal frame work, the tunnel, the ground wires and the engine itself.
There is also a ground wire on the startor plate under the flywheel. Luckly this is rarely the problem because the manufacture coats this ground connction with varnish when it was manufactured in Japan. The varnish usually seals this connection from any problems in the future.

Any other ground connection on the rest of the sled is suspect. From the front headlight to the back tailight and anything in between.
As for the grounds in the igniton curcuit this includes the external coil assembly, CDI box, Sparkplugs and again the internal coils under the flywheel.
Once again the ground connection under the flywheel on the stator plate was sealed with varnish when new.

So back to your no spark issue. While doing the origianl test with the plugs out, lets assume both plugs failed to spark.
Switch the original two plugs with two plugs that are known good plugs and repeat pulling on the rope once or twice.
Known good plugs can be new ones or ones from a running engine. If you still have two plugs with no spark we have learned something else.
The problem is not the plugs.
But let's say we now have one plug working and one not. This is where it gets good.
We now know one of the original plugs was bad!!! But the reason the second plug does not work is still a mistory but we are heading in the right direction.

There are two small wires that run from the CDI box to the external coil. Unplug both and switch them around. Retest by pulling the rope.
Is the same sparkplug working as before you switched the wires around? If so then your CDI box is at fault.
Or is the opposite plug now working? If so than you have a bad external coil.

But lets back track here and assume that when you put two known good plugs on nothing changed. Still no spark on either plug.
Make sure that the ground on the external coil is good. This ground may be a wire or it may be the mounting bolts themselves.
Whichever it is it has to be a good bare metal ground connection. No grease, no paint, no rust, no plastic, no rubber washers ect.
Is the coil mounted where it is suppose to be? If it is mounted to a plastic panel or dash it is not gounded.
Same goes for the CDI box. It has to mounted to ground or have a ground wire attached to a good ground.

If this all looks good then you are going to have to try and swap out a component. As it is unlikely that both coils inside the external coil have failed at the same time, go with a CDI swap.
Unplug all the CDI wires and reinstall a known good box. Mount this box as the original one was mounted to insure that you have a good ground on the replacement CDI.
Retest by pulling the rope.
Got spark now? Then your original CDI was toast.
Still now spark? Than your problem is on the stator.

On the stator plate there are two coils for the ignition curcuit. One exciter oil and one pulsor coil. There is also a third coil that is used for the lighting curcuit.
To gain access to the stator you will need to pull the flywheel. This requires a flywheel puller. Once the flywheel is off you can inspect and test the stator plate coils.
You can visually inspect them but to test them you will need an OHM meter.
You can visually inspect the flywheel also. Look for missing magnets, gouges or grooves. On Points systems look for a missing or damaged timing advance mechinisum also.

To test a coil, any coil for that matter, you want to find out if the grounds are good and see if the coil is shorted or open.
If it is "open" it will read infinity on an anolog OHM meter or OL on a digital meter. Open means there is no continuity in the coil windings. Open is bad.
If it is "shorted" it will read Full Scale or "0" on your meter. Shorted is bad. The short can be from one end of the coil to ground but not both ends.

What you want to see is resistance across the coil winding. There should be something there, just not zero or open. Sometimes there are known "specs" for a peticular coil.
If you read +/- 10% of the spec value you should be good. For example if the coil spec is 300 ohms and you read anywhere from 270-330 relax.
If you read 180 ohms or 400 ohms then you are out of spec. Coil replacement is needed or you can replace the entire stator plate with a new or good used one.

[JASONT]

Wow! Awesome tutorial! Thanks Todd!

I have pulled the coil in a fit and planned to take it to get tested. At the very least I'll have to replace the boots....don't ask.

I misread the tip about disconnecting the engine and only pulled the plugs for the switches, not the whole harness. I don't believe that helped me.

I do have lights when I pull it over, so I believe that eliminates the stator as the problem? The spark condition persists across both plugs either new or cleaned up old....

To be continued....

[sledhead16]

Todd is the guy to listen too!

[JDT]

Sometimes it is the damned things one finds.
I once bought a sled from a guy that said the recoil was broken. When you pulled the rope the engine did not turn over.
So I removed the recoil thinking I would have to fix the pawls or starter cage.
There was no flywheel on the engine!
The recoil was actuly OK.

And the part thing I mentioned about the two wires touching each other, seen that a least twice.
There is a wiring diagram for your sled shown here on the technical section.

Anytime I see a sled with modifications or repairs done to the wiring harness I always go through the whole harness and look for any screwups that someone did in the past.

An ohm meter is a very useful tool and they are not that expensive. One will save you a lot of time and headaches so it is worth the $20 or so.

But please let us know what you find and maybe post a picture of what you find.
Everyday is a learning experience when we work on a 30 year old machine that has had multiple previuos owners.

[JASONT]

I found a buddy that had a multimeter and since I already had the coil off, I pulled the CDI too. I think what these pictures show is that while the coil is good,
at least part of the CDI is shot...can anyone confirm?

[JDT]

The ability to test a CDI box with a meter is disputed.

Most will say it can not be done.

Your pictures did not make the trip.

[JASONT]

Well, crap. The coil showed readings across the grounds, the three wires in the harness, and the plug wires. The cdi, for what its worth, showed readings across the harness wires but not across the two wires that connect to the engine(red and white).

[harleysportster]

Jason,
If you know how to use an ohm meter, here are the ohm specs for the stator and ignition coil. If everything checks out, I would replace the cdi box. I advise not to buy a used one, but go with a new aftermarket such as the one that NewBreeds has listed.

[JDT]

Thanks for posting the additional info Pat.

Having the specs really helps.

[JASONT]

IT LIVES!!!! I checked a couple places on Friday for a new coil or cdi in stock.. obviously failed!! Ran up to the closest salvage and found both used with a promise to bring em back if they didn't work. I did have to solder a new ground onto the coil, but that was easy enough once I found all my scattered tools. Choked her and pulled her a half dozen times and she took took right off.

Now on to the sticky clutch and getting the idle right.

Thanks for all the help fellas. I will be around from now on for sure

[skoalmint]

Nothing Better than fixing a problem on a old sled ! Quite rewarding isn't it . Have fun with it ! Brock

[JDT]

Glad to hear it Jason.

[sledhead16]

all day long I would rather take the deeres out than my newer ones! Satisfaction is far more rewarding