Cobra Top Boy CDI Identification

[HabHazard]

Hello,

I found your forum a few weeks ago and have found it to be extremely useful, so I just want to start off by saying thanks for all the good info. 

On to the issue at hand, I bought a used Kymco Cobra Top Boy 50, (19km) roughly. I have the drivers manual with it also, and it has proven to be almost totally useless for tech issues. I have a couple of questions to post to you folks.

1. How can I determine what year the scooter is? (can find nothing in the manual)
2. How do I find out which cdi unit is the proper unit? A/C-D/C.... hooked up the battery and had no voltage at the connectors, most likely A/C from what I read. Currently have the unit out of the bike for reasons explained below.
3. How can I test the cdi unit to verify it's good/bad?

I've had the bike for about 6 mos. or so, and am very happy with it. I did start noticing a decrease in hp and speed a month or two ago. I've pulled the carb and cleaned it, new plugs, cleaned the air filter and resealed the air intake sys. (found a cpl of leaks), and installed a new leo vince zx handmade exhaust.

From what I have read on the forums it sounds as though the cdi unit is the culprit, but would like to verify that, and make sure I am ordering the right unit.

Thanks in advance for your time. 

[thebatman]

On the "# plate", the date of manufacter should be on that plate, usually located on the downtube...
Try taking out the battery and see if she'll crank.. If i'm not mistaken, if it'll run without the battery, it's a d.c.....the cobra should use the same as the ppl,s9??? (seems you found info here on that tho...lol) If you'll jot down the wires or looks, i could look at my s9 and see if same maybe, try to anyway.
Have you checked out the cvt yet?..  I would start there before i bought a cdi for sure.... A loss in hp/spped could be due to worn roller weights, worn belt, dirty cvt, worn springs

[sidthesloth]

I reckon a dc cdi won't run without a battery.

[HabHazard]

Thanks Guys,

I did pull the battery and attempted to kick start it, no joy. Reconnected the battery and it fired right up.

I also have an a.c. circuit tester which sense's a.c. voltage thru the insulation (had forgotten about it) I put it in the harness just behind the connectors to the cdi and it lights up when the engine is cranked with the kick start, so looks like it's an a.c. cdi...

You jogged my memory batman about a test used on older model cars to see if the battery or the alternator is bad. (not recommended for newer cars) Start the vehicle, (via jumper cables) pull the neg. battery cable, if the car keeps running, the battery is bad, if it dies the alternator is bad. I sure hope that is not the case here. Tough fix from what I've read. I also checked for spark at the plug and it's there, can even hear it crack, appears to be yellowish/blue in color, so I'm assuming (don't like that word) that the spark is good.

I forgot to mention that the roller weights are new, 6.5g, and the variator is very clean. The belt appears to be in good shape. Not sure about the springs in the clutch though, I dont have an impact, so i'm not able to get the bell housing off atm.

I think maybe a compression test may be in order here, 19k km on it, if that's the culprit, I have a 70cc kit that came with the bike, just have to pull the head and take it to a machine shop....

One other thing that i forgot to mention was that the engine usually (sputters) lately when riding...

I'll check out the frame and see if I can't locate the (plate) had forgotten that too, I guess I shouldn't have done all that lsd when i was a teen.  

Any other ideas you guys have is very welcome/needed.  

[sidthesloth]

If it has started  sputtering, check and clean the air filter.

[HabHazard]

Issue solved, rings were worn, and the piston has a small crack on the top. R&R'd with new, runs like a scalded dog once again. Premixing atm just in case oil pump is inop. Ty for you time gents. 

[JENNY]

If you could verify the vin 17 digits, I can get you the info or even the 10th digit from the right 8the from the left, I could help.

Jenny
tnt cycles
www.tntcycles-atv.com


Also, if you run a unit that has a battery, with out the battery, you could knock the stator out.  If you can't find the vin location, please let me know and I will look and see where it is located.