Aftermarket ignition box problem on Tforce

[Rob G]

So, my daughter's Tforce was having problems running above about 1/2 throttle on our last ride. Got it home and dug into it to find a horribly carbon fouled plug. I tore into the carb and found nothing of note so I put a new plug in it and fired it. It almost immediately fouled the plug again. Swapped the carb off one of my other machines and no change. So... not the carb. Come to find out it's the CDI box. So, I ordered 2 coils and 2 upgraded CDI boxes from VMC. The parts come in and neither CDI box will fire on the machine. These are the blue 5 pin AC boxes listed as "racing" CDI. So I get with VMC and they happily ship 2 more. Still nada. That's 4 CDI boxes that won't fire on this quad.

My question is, has anyone used these boxes? If so did you have issues with them? If you've upgraded the CDI on a 5 pin AC machine, and you're happy with the upgrade, what parts did you buy?

Thanks all.

[Al]

I did the upgrade. Works better. My problem is it will not start with the upgraded cdi when cold. It turns over then sounds like advance timing engine knock when it turn over. If I start it with the old cdi warm up my machine then put in the performance cdi, start perfect. Worth the upgrade for ten bucks!

[Rob G]

Thanks Al. After you posted this I did some poking around on Amazon and other places, seems that the problem you have is relatively common. I think, since this is on my kids quad I'll go back to stock for reliability and ease of use but keep the aftermarket box for a project. Appreciate your input.

[FLASHLIGHTBOY]

I think really does a little bit of performance matter ?? I would want the starting ease before performance stuff... no problems is better..

[Al]

Totally agree but it does pull harder and drive faster.