CDIs
 

A lot of people, myself included, have asked if performance CDIs make any difference. I found this video on YouTube:

https://youtu.be/i5OHZl14ce8

Apparently, it worked for this guy!

Enjoy the Ride!

Only problem with that is that it doesn't necessarily prove anything for the CB/CG motors, as he's testing with a GY6.

Since it's a scooter with a CVT, which basically keeps the motor at a fixed RPM once it's going, it doubly doesn't tell us much for the motors and motorcycles that this site is generally concerned with.

It makes the throttle response quicker, in my experience. An hp cdi without intake and exhaust mods will normally not be very noticeable.

There is an adjustable " purple box" CDI that MegaDan tested ., that i also switched to ( from a blue box like the one in the Video ) on the strength of his review that i now swear by .You can find Dans link to it over on the dual sport page .He of course uses it on a 250 but it works fine on my Vader 125 as well.


I was fine with the blue box and it worked well , and there is nowhere near as huge a diff between it and the purple box as there was between the stock one and blue box - but , there was a small improvement with the purple box and it is adjustable which allows for tuning between torque curves for stunting ,and

curves for track days which are more top end / high rpm .for the very few extra dollars you really cant go wrong.

Yeah, the adjustable purple unit does make a decent difference, nothing huge, but being able to shift the advance curve around is kind of nice.

oh , one last thing.Make sure you get a DC CDI for Vader 125's , i am not 100% sure of hellkats use the ac CDI or DC but i would assume they use DC.


AC CDI box is mostly used on pure dirt bikes etc that are kick start only and dont use a battery, or at least dont need one to run , like a magneto set up .

GY6 engine high RPM's + wide-open-throttle excessive cylinder head temperature, contribute to this.

I have tested 4 CDI boxes back to back on my CG250. You can tell minor differences in the advance curves between them, but as a whole the curves all seem very similar. The blue one felt mildly stronger than my stock one but made for harder cold starts. I had a little Red unit that was stated to work with every engine under the sun, felt about the same as the stock one on my bike, maybe a hair more advanced, but not much. Keeping it as a backup under my seat. The purple adjustable one can have very strong low and mid range when adjusted in favor of the low end and doesn't lose any pull up top over the stock one, but like the blue unit it can make for some harder starts when you advance the curve lower in the RPM range. None of these units tested have a rev limiter, so it is something to keep in mind. My engine naturally limits itself past 8500 by just running out of breath, but you can potentially over rev going down hills, so be very aware of that.

At the end of the day, I think it is safe to say that most of these cheaper AC fired bikes and scooters all use very generic CDI units that all share the same internals. I felt no loss on my Hawk at any given point. The only variable between them will likely be the rev limiter.

I actually have a Procom CDI for a CRF230F on the way to test out as well. This is a unit with a few degrees of advance built in and the CRF guys swear by it. I will be curious to see if it is worth the $40 price tag. It does have a rev limiter, but it's set at 10,000RPM, which is useless if you have an OHV engine, but if you have one of the OHC motors and an AC CDI, it might just be the ticket.