I have a 70cc quad. The only name on it is venom motors. The owner’s manual says “49/70CC-4T”. The quad is about 2-yrs old and has been sitting for about 1 ˝ years (has about 6 hrs on it). I am unable to get any spark! The ignition coil ohms out ok but I have no voltage from the CDI. One thread said “The ignition coil output in the CDI wiring harness connector should measure less than 1 ohm (but not zero ohms) to ground”. I have zero ohms from the ignition coil wire coming from the CDI to ground… does this mean I have a bad CDI?

 

That test was supposed to be done with the CDI unplugged and stored somewhere else. What was being measured was the ignition coil and the wires from the CDI connector. With the CDI else where the meter would have no way of knowing whether the CDI is bad or not.

When you measure resistance be sure you are on the proper scale. If you expect to see less than 1 ohm then you should be on the lowest scale possible (like 2 or 20 ohms full scale). If you were were, for example, on the 20K ohm scale (20,000 ohms or 20 kilo ohms) a typical 0.5 ohm coil readng would be 0.0005 kilo ohms. Your meter can't display that many digits, hence it does the best it can by displaying 0.00 KOhms.

But did you measure the kill switch wire first? Most no spark problems are caused by that. Turn on the ignition and set all your kill switches to the run position. With the CDI disconnected and put elsewhere, measure the resistance of the kill switch pin in the wiring harness to ground on the 10K ohm scale (10,000 ohms). It should read open (infinite resistance, or the same reading as when the meter leads are hanging free). If it reads shorted (zero ohms) then your kill switch circuitry needs attention.

 

Thanks Lynn. Hopefully you will bear with me, I’m far from the expert but I do have some electrical skills… I disconnected the “Remote engine stop switch” located on the rear frame. I then checked continuity through the engine kill switch. I had continuity in both positions on the switch so I disconnected the switch. The switch works but I still have continuity through the brown and black wires going to the kill switch, both with and without the CDI plugged in. I checked and also have continuity to ground from black to ground and from brown to ground. Any suggestions?

 

If I understand your post correctly, you are measuring the kill wiring as shorted to ground from the handle bar kill switch. And you've disconnected the rear tether kill switch by unplugging the wires to the switch (and not just pulling off the rubber plug to the rear thether switch). Correct me if I'm not understanding...

If the kill switch wiring is shorted to ground you will not get spark. If this is the case you must fix this before you can go any further.

I don't know anything about your specific quad - especially black and brown wires since these are non-standard colors. Let's make sure you have the typical generic chinese CDI...

Is this a picture of your CDI:



If it is then let's continue. If it isn't then we need to reset and start fresh.

{assuming generic 5 pin CDI} Measure the kill switch wiring harness resistance to ground from the CDI connector with the CDI unplugged. All kill switches must be set to the "run" position, and the ignition must be "on". Don't measure it from anywhere else. That's the hard way. The CDI is at the receiving end of any and all kill switch signals. What you want to do is look at the CDI connector for a short to ground, then unplug all the possible kill switches one by one until the short disappears. Then you've found the culprit.

The possible kill switches are:

1) Ignition switch (one of two ganged switches on the same shaft)
2) Handle bar kill switch
3) Lanyard tether pull switch
4) Remote Control module

If you still register a short to ground on the kill switch wire at the CDI then you have a pinched wire to the frame somewhere in the harness. If need be we can cross that bridge - but look for bad switches first because that is much more likely.

 

Thanks again Lynn! That is the same CDI and the kill switches all test good (didn’t realize I needed the ignition on when I tested last time). Yesterday I went over to my friend’s house who has the same quad and we swapped everything out and his ran with all my components. The last item I checked was the ignition coil and his didn’t have a spade connection so we tested both together (with a good ground) rather than splicing wires and his had spark but mine didn’t. Wish I had time to properly test but I am pretty confident this is my problem so I ordered one last night. Funny, the ignition coil is where I started. I didn’t have enough continuity from the spade to the plug connections to get noise on my meter and I was confident it was my problem so I went to the Suzuki shop and the gentleman talked me out of replacing it. We even ohmed out the new one he had and got the same readings. Nevertheless, I have my fingers crossed and should know by Friday… Have a Merry Christmas and I will let you know if it works !

 

well, i replaced the ignition coil and got spark but then i ran into carb issus , then had to replaced the plug and I lost spark again! I ended up finding an intermittant short in the ignition switch (your post helped me issolate it quickly, thanks!) Finally, I got it running. Runs great but won't idle yet... Thanks again!!!

 

Lynn,
Sorry if I am hijacking this thread, but I'm having the same issue- no spark.

I purchased this quad from a friend at work, who purchased it from a "side of the road dealer". The quad has no identifying marks as to who made the bike, but it has a 97cc TZH engine and it has the same CDI as you pictured.

I am attempting to follow your directions to test the kill switch circuitry. I have the CDI unplugged, a test lead pressed to the bottom center connector pin of the harness and the other to ground. I am using a Craftsman digital meter that has "Auto Ranging". I can select a range, but I'm not too proud to admit that I'm not an electrical guy. Your post said that the meter should read O.L., just as if the leads were hanging free from the meter. When I touch the pin with one lead and put the other to ground- my meter begins to bounce all over the map. I am unable to come up with a definite reading, but while in Auto Range, it's definetely not O.L.

I purchased this bike with intents of fixing it and surprising my son with it for Christmas. That didn't happen and unfortunately the money I spent on the used bike prevented me from surprising him with something else. I really want to get this thing running for him. I'm hoping you won't mind helping me out with this please.

The information I received from the previous owner was that the quad ran fine one day, then wouldn't start the next. He tells me he and a friend removed the alarm system from the bike before this issue started.

I have documented wiring colors to and from components of the bike. I would very much appreciate your help with this. I have been reading everything I can find for the past eight days and beleive I have learned more from this one thread than everything else I have read.

I will gladly test components or circuitry as you deem appropriate and report my findings.

Thanks in advance,
Chevytech

 

Another question:
What is the component that has "fins"? It looks as though it's about 2" square, it's about an inch thick, it has 4 pins and has fins for what I'm assuming is heat dissapation.

There is some Asian writing stamped on one side that is mostly worn away and "12V" stamped on the other side.

Thanks,
Chevytech

 

It is strange that your meter bounces between ranges. Are you sure you on ohms scale? When you short the leads together does the reading go to zero? Do you have another meter to try? The kill circuitry should just be a group of wires that is shorted to ground or not shorted to ground. A meter shouldn't get confused by this.

Try using a small screwdriver to pop out the kill switch wire in the harness connector. Plug the connector back in and try to start the quad. Of course be sure to check all the kill switches to make sure they are in the run position, and make sure the ignition switch is on. Have a pair of insulated pliers on hand when you do this. If the quad starts up the only way to kill it is to turn off the igntion *and* use the pliers to shove the kill wire back into the CDI connector. There is high voltage on the CDI kill pin when the engine is running so make sure you only hold on to insulated part of the pliers.

If the quad still doesn't start then test to see if you have spark. Do you know how to do this?

There's lots more tests to do of course. but let's take small steps. Let's get the meter readings making sense, and see if you have spark.

The "finned" 4 wire device is your voltage regulator. It is important, but it has nothing to do with whether the engine starts or runs - unless your battery is dead and the starter won't turn. If the starter turns you can ignore the voltage regulator for now until you get spark and get the quad running.

 

OK, I am leaving work now and heading to Radio Shack.
I brought my meter to work with me so I could have one of the Instrument and Electrical guys take a look at my meter.

Embarrassingly, he found that I have a blown fuse. It appears that at some point I checked voltage while plugged in for resistance. I will pick up a fuse on the way home and re-check the bike.

I will post the results this evening. Thank you very much for your help, I do appreciate everything I am learning.

Chevytech