CDI Improvement

[jaguar]

I found out the stock KDX CDI limits top end power in two ways: 1) it uses a 1.2uf capacitor instead of the normal 1uf and that causes a stronger spark at low RPM but weaker at high RPM, 2) Its timing curve is not retarded enough at high RPM and that limits top end power. So, being an electronics technician, I made my own modified KDX CDI which fixes these two problems. I used my KDX200 on the street (in Paraguay), trail, and MX track and found no drawbacks, only benefits.

 

[Trekspyder1]

That's amazing. Nicely done.

 

[jaguar]

Years back people wee interested in it and I sold about 10 of them but now with the low economy of the new world order no one is interested any more. It's a shame because it really does improve top RPM power.

 

[Chuck78]

I'm interested in an improved ignition... are you making any more? Another fella was making some, but was postponing any more until he decided on a better timing curve or multiple adjustable curves, as a lot of people didn't like the harsh kickback that the high performance ignition allows when the situation allows it.
It was also indefinitely postponed until he was more wrapped up with the e-start conversion kit he was designing for the KDX H-series...

 

[jaguar]

I am waiting to receive the main capacitor to finish one I am making now. You can message me with your email so I can inform you when it is ready.
As to the "harsh kickback" I have no idea what that person is talking about. I sold 16 previously and never had any negative feedback. I used mine for over a year and never had anything to complain about. Maybe this person who tried to imitate me didn't do such a good job and used a SCR transistor with different specs as the one I used. If you have a Ricky Stator coil then it puts out higher voltage and makes the ignition more advanced and needs to have the stator plate moved CCW some to prevent excess ignition timing below 5000 RPM.

 

[Chuck78]

All very good info to know, Jag!
I actually had replied to your posts on kdx rider in the past year, but I don't recall seeing a reply.

The other guy making his own ignition boxes liked the very aggressive hit off the bottom he achieved, but noted that some people did not like the kick back it gave.

I would like some additional enhanced bottom end, but I also don't want it to take off violently like my 220 did with the fatter FMF Gnarly Desert "rev" pipe, Lectron 34mm, VF3 reeds, modified head, and the ignition timing set on the top mark... That was just plain insane and dangerous in tight woods scenarios, I dialed the ignition timing back to just a few hairs above the middle mark on the stator plate and it was still fun and slightly sane! That was a year ago, and I'm itching for a bit more power again, also maybe time for a winter piston ring change and Wiseco piston inspection...

 

[Chuck78]

Jag, I see you have an 89 KDX200. How do the 89-94 vs 95-06 ignitions differ?

 

[jaguar]

They have a slight difference in the timing curve but it's been so long that I don't remember what it was. The main improvement my CDI gives is at high RPM because the timing there is more retarded which contributes to power and allows it to rev out farther.

 

[Chuck78]

Hey Jag, I was reading on KDXRider that you recommended a Honda CR ignition coil. Any tips on what years have the 55mm bolt hole spacing that you called for? These have a hotter spark from the sounds of it.

 

[jaguar]

I'm not sure what years. Just make sure the spacing is right.

 

[Chuck78]

I saw some other info saying that 97-99 CR125/250 was the correct 55mm spacing, FYI!

 

[Chuck78]

I'm thinking that moving up from the stock PWK33 carb on a KDX220R, to my 34mm Lectron or 36mm bored PWK36 Air Striker, plus the Jaguar ignition offering more rev-out, I may be able to better pull off running the FMF Gnarly Woods # 020057 pipe that enhances the low end power. Some people like to spout off about how the low-end-focused 220 is no good with the low-end-enhancing Gnarly Woods 020057 pipe, but others like a writeup on dirt rider here and some on KDXRider will say that it is the most amazing combination for technical terrain, especially with a modified head and larger carb. I have both, as well as getting my bikes set up with aftermarket ignitions. Any top end losses from the woods pipe will be offset somewhat by the higher compression head, larger carb flowing more air, and the better high RPM timing of Jaguar's upgraded CDI box circuitry.

I think I'll run the Lectron on the Woods pipe if I get it, and save the RB modified 36mm PWK35 for the ported cylinder and 223cc overbore that I have here on the shelf... That should be severely potent!

Ultimately I'm trying to round up more interest in the more superior Pro Circuit Platinum 2 pipe for the KDX which offers similar top end RPM power to the FMF Gnarly Desert, but far more low end power than the FMF Gnarly Desert. Truly the best overall pipe for the KDX, but they haven't done a production run since 2018 or early 2019, and you have to call or email to be added to their request list / waiting list for the Platinum 2 pipe and now even the Type 296 spark arrester silencer. VERY NICE PRODUCTS from Pro Circuit. The FMF stuff is great, the PC stuff is even better. IF it were available!!!

 

[jaguar]

I am starting to make the performance CDI again so if you are interested let me know. My web pages about it is at Adjustable replacement KDX 175/200/220cc CDI