Hi, I just bought a 2008 Asun 300 and when I took it home it wouldn't start. Narrowed it down to no spark and started searching for shorts or loose connectors in the ignition system. I never found anything out of the ordinary and then one day it just starts right up and runs great. I put it all back together and took it for a 10 min run, then parked while idling. Stalled and then wouldn't start again. Once again no spark. For the following few days it would do the same thing; run while riding, idle then stall. Every time it stalls I check for spark and I have nothing. I have also changed the spark plug at this point to see if it is fouling, but no luck. Two other things were odd to me: the battery died the first time it stalled and not the second. I checked the charging next time it ran and it was charging. Might just be a bad battery, I have to go get it load tested. Next thing is the speedometer flickers when cranking or revving up while running. I did find a wiring diagram for it if this would be helpful. Thanks in advance.

 

I've never heard of these quads. You say you have a wiring diagram? Can you send it to me? Or post a link to it? If you have a machine readable diagram then PM me and I'll PM back an email address to send it to.

If you jump the quad to your car does it start up better? That would eliminate any battery issues (which also include hard starting at low cranking speeds).

 

Hey Lynn, sorry it took me so long to respond. Gone for the weekend. No it doesn't make a difference when I boost it with a boost charger. I am not good at sending links. I tried to post the link on here but it omitted it from my post.I can try to send it differently if you have a suggestion. You might have to type slowly and use small sentences. lol.
I have read a lot of your forum replies and from your readings, I try it on mine but I want to make sure I am headed in the right direction. Does this sound like the behavior of a bad stator or CDI to you? I have checked the voltage from the stator while cranking and I can only read under 1 volt AC to ground. Between the 2 wires I read just over 100 ohms between the 2. The 2 wires from the stator (for ignition), go to what seems to be a pickup coil. I pulled the wet stator and the 2 wires go to a small box mounted beside the main stator coil. Thanks in advance. Any advice is an asset at this time. Eli

 

If it is just a web site address then just type it in the post. Even if it doesn't get marked as a link I can figure it out. If you're trying to attach a file from your computer that is a little harder.

Spark generation needs the stator and the CDI and the coil and the spark plug (and of course correct wiring hooking all these things together)

The stator always provides one, and often two things to the chain:

1) The Trigger Pulse (always present): A small signal voltage that tells the CDi when to fire the plug. Sounds like that is what you measured above.

2) Power for the CDI: Most CDI's are powered from a moderately high voltage (a couple hundred volts) AC winding on the stator. Some quads have a CDI that is powered from the battery. These CDI's have a power supply inside that converts the 12 volts into high voltage to run the CDI.

A third winding (or windings) is also always present in the stator. This is used to charge the battery. It has nothing to do with spark and so you can ignore this part of the stator completely.

The CDI takes power from the stator or its own internal supply and charges up a large internal capacitor to several hundred volts. At the proper time, a trigger pulse from the stator tells the CDI to dump the capacitor voltage onto the coil primary winding. Hence the acronym CDI, which stands for (C)apacitive (D)ischarge (I)gnition.

The ignition coil is just a high frequency transformer that jacks up the couple hundred volts spike from the CDI to tens of thousands of volts to the spark plug.

The spark plug sparks and ignites the fuel.

The first thing to do is determine if your CDI is 12 volt powered or AC powered from the stator. Again I've not heard or seen anything about your quad. Does you CDI look like this?

 

ASUN

 

Chinese ATV Parts - Go Kart Parts - Scooter Parts - CDI Boxes - CDI #10 for Chinese 300cc ATVs
The first link will lead you to the wiring diagram if you go to DMR 300 ATV. Then parts and service manuals for download, then ASUN parts and service downloads, then 300cc ATV wiring diagram pdf. The second link on this post is a picture of what my cdi looks like. I am pretty sure my cdi is DC because I have a constant 12 VDC through the kill switch from the ignition to the cdi. Hope these links work. thanks Lynn

 

Eli,

Thanks for that link. There was a ton of info there on your quad and some other quads as well.

Your CDI is a bit special. According to the wiring diagram it is powered from 12 volts (as you suspected). The shut down switch removes the 12 volt power to the CDI, as does the ignition switch (through the main fuse and another secondary fuse in the fuse block).

The CDI trigger signal comes in on two wires, so that means you need to measure this signal voltage between two pins (blk/red and blu/yel) instead of measuring one or the other to ground.

So when you're *not* getting spark, crank the engine and measure the trigger signal pins on the lowest AC voltage scale on your meter. Measure each of those pins to ground as well (why not - more info is better).

When you *are* getting spark, do the same thing with the shut down switch on (so it won't start, but the starter still cranks). Compare the two results if you can get them. We're in the intelligence gathering mode. Everything is unknown, so the idea is to gather as much info as possible for possible use later. Let's try to bracket the two voltages between a working quad and a non working quad. If they are the same that points to something after the trigger signal. If not, that points at the stator trigger winding.

Switch to a higher AC scale as required and measure the voltage at the coil primary pin (blk/yel according to the wiring diagram). Crank the engine while you're *not* getting spark and record what you see. I think you should see lots of zero voltage reading with some fairly high random spikes in between. You should get significantly higher voltage spikes if the quad is running. You should get only zero volt readings when the shut down switch is in the 'shut down' position.

Lynn

 

I reread my last post this morning and noticed I forgot to have you test the obvious:

Make sure you have 12 volts at the CDI when you aren't getting spark. Also make sure the CDI is getting a good ground connection.

 

It won't fire today but I got what readings I could. Between the two trigger wires I got 0.1 VAC on the 200V scale, to the CDI and the connector from the stator while disconnected from the circuit. Trigger wires to ground,each read open. The black/yellow to the coil while cranking read 0 VAC on the 750v scale. I read 10.5 VDC at the CDI, on the pink wire, when cranking. As for the ground connection to the CDI, I read 0.3 ohms on the 200 ohm scale but the meter zeros out at 0.1 to 0.3. I just put a new battery in it so we can rule that out. It hasn't started for about a week so I don't know if I will be able to get any readings while running. Thank you for specifying what the reason for the tests is. It helps me in my process of elimination also.

 

Just out of curiousity what is the resistance of the trigger winding from end to end (betwen the two wires)? 0.1 VAC seems a little low, but it is hard to tell with the lowest scale being at 200 VAC.

You aren't getting any voltage spike at the ignition coil primary, so that indicates the CDI isn't being triggered, the CDI is bad, ot the coil primary is shorted to ground. The latter can be ruled by out by measuring the resistance of the coil primary winding. It should be a low value (like 0.3 ohms), but not zero ohms. So on your meter that reads 0.3 ohms with the leads shorted together you should see more like 0.6 ohms.