Just a FYI on getting a CDI that will work with the Honda CG125 based engine used on the Taotao 250 quads. Most if not all CDIs with the proper plug/pin configuration sold on Ebay and other places will not work with this engine. Even though they may be advertised to work with the Taotao 250 the timing is too far advanced. It'll kick back when you try to start it and even if you can get it to run it won't idle and will run poorly throughout the RPM range. I tried 3 different units from 3 different sources and none worked. The one sold by Taotao's parts outfit does work however, it just costs more.

 

How do you test one?

 

Plug it in and see if it works. You can also check the timing with a strobe.

 

Hugemoth,


Your post surprised me. I haven't looked at 6 pin CDI stuff for about a year and a half, and after you post when looking a bit. There is a fair bit of info from a competing Taotao sponsored forum showing several different ignition advance curves including the CG125 based motors. They are different than the CDIs I measured and took apart, but only at higher RPMs, and the CG125 curves show a more advanced curve then the ones I measured. So in fact the standard ones on eBay (or at least the ones I've looked at) have retarded timing advance curves compared to the CG125 curve - not advanced timing.


Plus, all of the curves I looked at showed exactly the same timing at idle. Thus I'm perplexed at any starting issues between the differing CDIs.


Second, I've taken apart and traced out the circuitry of several CDIs. I'm pretty sure I understand how they work, and how the timing advance works within the CDI. There is a little leeway on adjusting the timing advance in the electronics, but not a lot. Most of the timing advance min/max extremes are controlled by the pickup raised bump dimensions on the flywheel - not the electronics - unless there is a whole lot more circuitry in the CDI. But somehow I doubt that. Chinese quad companies aren't exactly on the forefront of technological innovation.


Third, one of the most basic and fundamental complaints of Chinese quad owners is the lack of wiring diagrams and service info. Some Chinese quad manufacturers have provided them, but others have not. To the best of my knowledge Taotao has not provided any wiring diagrams, nor technical manuals at all. Why is that? Yet they provide through their sponsored forum all kinds of ignition curves (only in Chinese). I just wonder why they are posting all this esoteric CDI ignition curve stuff, while ignoring the most fundamental issues like wiring diagrams .


Anyway, the main purpose of this post is to gather information. I want to learn more about this, and a little controversy can sometimes stir up the pot and get the info flowing. I'm often wrong, and am willing to be so again if it raises the general knowledge base .

 

I noticed in the original posting hugemoth refers to his 250 being based on a Honda CG125. I'm not familiar with Taotaos but is the 250 really based on a 125?

 

Excuse the quick reply but I'm leaving on a trip this morning.

I tested the spark timing on each of the CDIs with a strobe. The stock CDI and replacement unit from Taotao timing lines up with the timing mark in the window. The others from eBay which were advertised to work with the Taotao ATA250D are too advanced by several degrees at idle speed. Not sure what engines they work with, perhaps the GY6 type scooter engine.

BTW I also have 2 motorcycles with 200cc CG clone engines, a Lifan and a Zongshen. Both use the 6 pin CDI but the Lifan has the rounded plugs while the Zong and the Taotao ATV use the more square type. When I get a chance I'll try the various CDI units on the Zong.

 

Yes the engine in the ATA250D is indeed based on the Honda CG125. Chinese companies make CG125 clone engines from 100cc to 230cc that I'm aware of. They also make liquid cooled engines that are CG based, using the same unusual valve train, same transmission design, parts placement, etc.. Honda has a web page about the development of the CG125 here: Honda Worldwide | History | CG125 / 1975

I also have a Lifan 200 and Zongshen 200 motorcycles with CG125 clone engines. I've ridden the Lifan over 53,000 trouble free miles so far.

 

Hi, I have a 250cc commando chinese liquid cooled atv with no spark. I checked the ground at the coil and it's fine. There are 2 other wires that are connected to the coil.

I believe this atv has a DC CDI. It is double the size of the AC cdi boxes I've seen. It has a blue 6 pin connector housing with 5 leads inside. It does not have 2 separate connectors the the AC ones it just has one big blue plastic connector.

I believe the Stator and the CDI are working fine based on the voltage I pick up at the two wires supplying the ignition coil.

Here are the readings I found on the two wires supplying the coil:

- Black & red wire, Contant 12.95v DC as soon as I turn the ignition on

- Black & white wire, 0.12 - 0.23v randomly AC while I'm turning the engine over ( it seems like this is a pulse wire to tell the coil when to fire.)

Since I thought these readings were correct (at least I think but please correct me if there's something wrong) I moved on to measure the ignition coil resistance.

- Resistance between the 2 hook ups on the coil for DC & AC wires: 4.2 Ohms

Resistance from either the hook up (didn't seem to matter which one) to the spark plug boot: 20.2 K Ohms.

I thought these were within reason as well. But the ATV still will not spark.

I appreciate any help, I've been fiddling with this atv for 3 weekends now and I just want to get back on the trails.

Regards, Jack

 

You make quite a few assumptions, which may, or may not be correct. firstly the size of the CDI isn't all that important and no indicator if it is AC or DC. However a positive feed to the CDI unit does indicate DC, though Honda managed to produce a strange hybrid which feeds from both an alternator wire and the battery, but only seems to use the power from alternator to spark.

There are two different DC systems. One uses the battery to power the spark, much as the AC system uses the exciter coil fitted them. The other mimics the points system used on older cars and motorcycles, in that the coil is fed positive direct from the ignition switch and the CDI produces a negative pulse to fire the coil. You don't state what voltage you are getting at the coil. On many coils, the case isn't grounded at all, and spade connectors are fitted, one for earth, and one feed from CDI. If it does have a separate earth to the case/frame, this could indicate a car style DC system. If a positive wire to coil is being fed 12v from ignition switch, it is this type.

 

Thank you merryman, yes I just checked and I am getting a positive feed of 12.9V DC to the Cdi (black&red wire)

the coil is fed positive from the ignition and the pulse wire that also feeds the coil is reading around 0.001vAC and 0.3vDC. Both are constantly changing but all readings are within those voltages.

There is a ground wire attached to the coil and I have verified a good connection at 0.00 ohms.

judging by what you told me I think my system mimics the points system my only question left is if the pulse wire is sending the right voltage?

Could there be something wrong with the stator if the pulse voltages are wrong?