g1 ignition questions

Mattohio

I have came along a G1 1980 (j10-009290) Problem-no spark
I have switched with a known good coil (from a small dirtbike) and known working spark plug. still no spark.

I do get some voltage from the coil lead wire (orange). How much should I have? Any idea how to test the CDI unit and the CDI magneto?

Also, does anyone have a wiring diagram or service manual in electronic format?

Thanks

Matt

BGW

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GMB74

Most electrical problems on these old carts can be traced to loose/corroded connections and broken wires. If you are getting "some" voltage on the orange wire to the coil, that is a good thing. You probably have a bad connection somewhere. Make sure the coil is grounded. Check all your connections especially the four wires coming out of the engine, low on the right side of the fan housing. Chafed wires near the battery and exhaust are common. Wiring diagrams are available in the stickies up top.

Mattohio

Yes, checked all the wiring...cleaned all connections. The voltage on the orange wire spikes on the first couple rev and then falls quickly on the next couple revs.

kwest0425

Obviously, check for bad grounds, loose connections, etc.

Also checkout the magneto and cutoff switches. If you have an ohm meter/multi meter, its fast and easy to do, since it can all be done from the cable harness that is connected to the CDI.

Here's a troubleshooting guide that I put together when I had a strange ignition problem. I would get spark in forward and none in reverse. Problem turned out to be a loose magneto plate and broken ground wire.

I have a 1981 but I think it applys to all G1 model years

************************************************** ****************

G1 Ignition Troubleshooting

-Remove the positive lead from the battery.
-Remove all harness wires from the CDI.
-Using the ohm meter, verify that the black wire in the harness is grounded.
-Connect one of the ohm meter leads to the black wire. This remains connected for all tests below.

For each test, jiggle the various harnesses, grounds, etc. and move the crankshaft back and forth by turning the primary sheave (it helps to use alligator clips on the ohm meter).

**** Check the cutoff switches

- With the key off and/or the gas pedal up, the black/white wire should be grounded.
- With the key on (either foward or reverse) and the gas pedal depressed, black/white should be "open" (not grounded).

**** Check the magneto source/charging coil

- Place the ohm meter lead on the brown wire. This should read about 350 ohms.

**** Check the magneto pulser coil

- With the key in the off position, verify that both the white/red and the white/green are "open" (not grounded)
- Turn key to "forward". Verify that the white/red wire is now grounded and the white/green wire reads about 15 ohms.
- Turn key to "reverse". Verfy that the white/green wire is now grounded and the white/red wire reads about 15 ohms.

**** Check the spark coil primary winding.

- With the ohm meter lead on the orange wire, verify the primary spark coil reads about 1 ohm

************************************************** ****************

sho305

If not clear, the G1 has a both forward and reverse starting solenoids and ignition pickups. That can help you figure things out because if neither is working you know its not the redundant parts. Also frame is not ground on these, you must check all ground wires and connections it is common to have failures in them at this age.

Mattohio

Thanks Kwest and sho305

thanks for the tips in the post...just got in from the shop ....still trying to track down problem...I think its the CDI (wonder how much that will be)...I tested the cart with the ohm meter exactly like in the above post...all checks out...but the pulse coil does not drop or rise much in ohms when engine is hand cranked...I would think the pulse could would be more like and off/on set of points.. Might pull the flywheel to make sure everything in in place...
Anymore ideas?

kwest0425

Actually, measuring the resistance (ohms) of the pulse coil should be pretty much constant (about 15 ohms). I only suggested moving the crank back and forth in case you had something loose in the magneto like I did.

Before you pull the flywheel, recheck the magneto at the mag harness coming out of the back passenger side of the engine.


Disconnect the 4 wires and test as follows:

-Black wire should be ground. (engine block)
-Brown wire is the charging/source coil and should be 350 ohms. (Measure between Brown and Black.
- Measure between white/red and white/green. This is the pulser coil and should be about 15 ohms.
-You might also want to measure white/green to black and white/red to black to verify they are not grounded.



Hopefully its not the CDI. They can be expensive unless you can find a used one.


B-T-W, check the Sticky at the top of the "Gas Yamaha" forum. You will find a link to electrical drawings for these carts. The 79-81 and 83-on has a couple of problems but I believe the 1982 is accurate for 79-82.

good luck.

-kwest

sho305

They call the CDI the 'Ignitor' and they are not cheap, better to swap a known good one before you buy if at all possible.

GMB74

The pulse coil generates an AC output rather than an open/closed signal like ignition points. The CDI box "knows" that when the voltage rises to a certain level it is time to trigger the ignition coil. You would need an oscilloscope to actually see what is happening, but if you attach an AC voltmeter to the pulser coil wires you should see a low voltage reading when cranking. This, plus the resistance test should confirm the pulser is working.
Sho305 is correct, try a known good unit first if you can. It is not common for the CDI box/ignitor to fail, but it does happen.

chevyguy82

i am having the exact same problem. did you ever figure out what was wrong with yours? i just bought a 1979 g1. maybe 4 volts from brown wire. 323 ohms. black wire is grounded i pulled flywheel and everything was packed with dirt. i cleaned that and still the same result. still no spark. no power to orange wire out of cdi.