Spark Problem 74 Cheetah - Snowmobile Forum: Your #1 Snowmobile Forum

articcatbill · 08-12-2008, 05:02 PM

I have a 1974 Cheetah 440 with spark on the mag side only. I unhooked everything (ignition, kill switch….) pulled the fly wheel so I am just dealing with 2 wires coming out to the external coil. One is red the other white. With only those 2 wires hooked to the external coils (one to each) if I turn the flywheel by hand I get spark on the mag side. If I Switch the wires (white to red and red to white) I get spark on the PTO side. So I have excluded the external coils and everything except for what is under the flywheel.

It is the white wire side where I am not generating spark. When I pulled the flywheel The first thing I did was replace the condenser on the white side. Didn’t help, points looked good and open and close fine, gap seems fine. The condenser on the red side had been replaced at one time. I have checked the continuity of all the wires and can not find a break in any wires. I ohmed the coil seems reasonable, but am thinking it must be fine since I am getting spark on one side. The spark on the red side seems nice and strong.

I am stumped I have been trying everything I can think of for the past 2 hours. I am not sure where to go next. Any ideas??????

I will toss out this one more oddity that I noticed yesterday, when the ignition switch is hooked up, when I have the key on, I only get spark on the mag side. When I turn the key to the off position, I get good spark on the PTO side and weak spark on the Mag side. That is where I spent yesterday looking, but I figured today to eliminate all that and just focus on the internal and external coils, fix that and then worry about any other wiring issues.

Help/ideas are appreciated, thanks.

**RJ Gleason** · 08-12-2008, 08:25 PM

Have you tried putting a jumper in place of the ignition switch?
Might just be a bad switch.
Have you unplugged all the switches, the kill and throttle safety switch too?

articcatbill · 08-12-2008, 09:03 PM

Yea I tried a good switch first thing this AM, I was really hoping that would do it...

I have a matching Cheetah that runs, so I pulled the switch from it and tried it this morning. I also made sure that "good" one will run with out the wiring harness from the switch hooked up. So I unhook the wiring harness from the running cheetah, I was surprised but I had spark and it started.

So then I unhooked everything from the "bad" one and started working on it with out the wiring harness attached. Figured I would go as simple as possible.

Thanks for the idea, since I put the new condenser in I didn't try it with the switch hooked up, so that is something I can try tomorrow.

Thanks for the idea, any others

Oh and yes I did unplug all the switches, I know the kill/throttle switch isn't right since it will kill all spark when hooked up so something is up with that, figured that was for another day once I had good spark...

**RJ Gleason** · 08-13-2008, 09:10 AM

you're on the right track now!

articcatbill · 08-13-2008, 08:54 PM

Tried it today with ignition hooked up and new condenser, same problem.

A few questions that maybe someone can answer that will help my trouble shooting:

I don't have a wiring diagram, so how is it the ignition switch kills the spark? That may help me understand how the spark switches cylinders when I turn the key off and on?

I replaced the condenser on the "bad" side, could the other condenser effect the "bad" side?

Am I right in assuming the external coils are good since I can get spark to each plug by switching the wires coming out of the magento?

Any help/answers appreciated, thanks.

**RJ Gleason** · 08-14-2008, 09:18 AM

The spark is killed by grounding out on the switches.
If you have all the switches unplugged, is the spark still the same?

articcatbill · 08-14-2008, 10:46 AM

Yes when all the switches are unhooked I only have spark on the Mag side. That is the same thing as when the ignition switch is hooked up and turned on, I have spark on the mag side.

When the ignition switch is hooked up and turned off I have spark on the PTO side and not the Mag side.

Thanks.

**RJ Gleason** · 08-14-2008, 08:46 PM

Short in the exciter coil.

articcatbill · 08-14-2008, 11:24 PM

Thanks RJ, I ordered the parts tonight, I'll post results...

articcatbill · 08-30-2008, 09:03 PM

Well today another old cat came to life :-)

I replaced both exciter coils, and points and condenser while I was in there and I finally got spark in both cylinders and got it running. It ran well enough it would idle some so I could check the seals, I need to replace the PTO side seal. I am going to re-build the carbs on each of them next, and see if the other one needs a seal.

I do still have an electrical issue I can get some help with? The ignition switch works perfectly key on spark both cylinders, key off no spark.

But the kill switch is the problem. If I hook up the kill switch I lose spark in the mag side cylinder, the PTO side still has spark and if I turn off the kills switch it kills the spark. So for some reason having the kill switch hooked up, will kill the spark in one of the cylinders, any ideas?

**RJ Gleason** · 08-31-2008, 07:05 AM

Replace the kill button switch.

articcatbill · 08-31-2008, 07:09 PM

Well it is pretty new. The previous owner replaced it thinking it may be the problem when he was having the one cylinder spark issue. So it was replaced just before I got the sleds.

But if the kill switch itself might be the problem I can pull it apart and check that a wire wasn't broke etc when it was installed. I was thinking if it was the kill switch it would be killing both sides not just one. I really wasn't thinking that it could be effecting one side only. But if that is the case I will look in that direction first.

Thanks.

**RJ Gleason** · 09-01-2008, 05:58 AM

There are three wires that go into the switch. It kills the engine by grounding the two coils against each other. If one of them is going to ground, then you will only have spark for one cyl.

articcatbill · 09-03-2008, 11:16 AM

OK, makes sense, just need sometime to look at it, thanks again....