Adjustable CDI for KDX 200 and 220- Interested?

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Adjustable CDI for KDX 200 and 220- Interested?

Post by SS109 »

Alright my fellow KDX'ers, I have a few questions to ask you.

As some may recall I had planned on making my own adjustable CDI for myself after the one I had purchased from Jaguar failed on me. I loved how it woke my 220 up even more and gave it more pull up top (over rev) and was disappointed when it quit working. I planned on just buying another from him but his price has gotten so high now that I felt it was worth the effort to just make my own. BTW, not knocking Jaguar's price as I know he knows what he's doing, has put a lot of time in to his CDI, and lives in a country that I assume probably costs him more to get his supplies for building them.

Anyway, sadly, life had kind of gotten in the way and I placed it on the back burner and forgot about it. After it was brought back to my attention by another member recently, I've decided to jump back in and get it done. I was thinking about building 2 of them for myself but started thinking maybe some others might be interested in one as well?

This CDI will work for both the 200 and 220 engines. It will have a total of 4 simple on/off adjustments that would allow you to tweak the overall timing curve. It will be pre-wired with the correct terminations to be plug and play for '95+ KDX bikes and shouldn't be hard to adapt, if necessary, the wiring for the '89-'94 bikes. These will be hand assembled by me and will be tested for proper operation before I will ship a single one. All of the actual electronics will be water, dust, and vibration proof just like the OEM CDI is. I will stand 100% behind my work and everyone here can hold me to it! I will include instructions on how to install and to dial in the best timing curve for your bike. (It's easy to dial in the timing curve but does take 30 minutes or so depending on how fast you work) If enough people are interested I will probably build 10 total (more depending on demand) and keeping 1 or 2 for myself. The other 8-9 (or more) I would make available to KDXRider forum members.

I know there are some cheap stock type replacement CDI's on Amazon for around $42. Then you have Jaguar's adjustable CDI for $199 plus $31 shipping. From there the prices just keep going up with some super nice ignition systems that allow for all sorts of tweaking. I can already tell you that my CDI isn't going to be cheap per se as I can't build anything as cheap as the Chinese can. I'm not trying to get rich here but need to cover the costs and maybe make a buck or two for the amount of work it takes. I honestly don't know yet how long it will take to build one but I'm sure it's going to be at least 1 hour minimum on the labor and I'm thinking more like 2 hours. I'm thinking it would be somewhere in the $100-150 range.

Ok, on to the questions!

Question #1: Would you be interested in one?

Question #2: Is my projected price range what would you be willing to pay for such a CDI?

Question #3: Please tell me what you think? Too costly? Just not interested? Any and all comments are welcome!
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by Slick_Nick »

How much of a difference does it make, having an adjustable unit? I think a lot of us maybe don't know (because we haven't felt it) how much of a difference ignition timing can make on a two stroke like the KDX. I'm genuinely asking, all I've ever played with is rotating the stator plate, haven't seen what an aftermarket CDI could do. If it's something that's able to unlock some hidden power or tractability in the KDX, absolutely I'd be interested. I run race gas in all my bikes, so if this is something that would allow me to take full advantage of the higher octane, then you can put me down for one.

If the cost / benefit ratio is hard to justify, then I think it may be a tough sell. I know you had yours fail on you far from home, some of the trails I ride are a good 50 miles from the truck, so this would be a concern for me as well. I guess I could keep the stock one as a spare in the backpack.
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by doakley »

Can you tell us more about what you expect the advantages of your CDI to be. I know you said more rev on too, but what about low and midrange power?
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by SS109 »

doakley wrote: 01:55 pm Dec 19 2021 Can you tell us more about what you expect the advantages of your CDI to be. I know you said more rev on too, but what about low and midrange power?
I'll try to answer as best I can.

The advantage of an adjustable CDI is that it allows you to tailor the ignition timing curve to dial in a wider power range (or even a narrower one if that's what you like! :mrgreen: ) , to take full advantage of any engine mods you have done, the octane of fuel you use, to help compensate for high altitude power loss, give better throttle response, can make the bike more tractable by smoothing out the power curve, and to make the engine more efficient overall and possibly even get better fuel mileage. The more mods the engine has the more benefits you get from having an adjustable CDI. It might pick up 1 or 2 hp at peak but it's the hp and torque below the peak that I'm always looking to optimize.

This CDI would allow 16 different variations on the timing curve with 4 mainly affecting the low mid, 4 for the mid to top, and then 8 combinations of them together. Plus, you can still play with your initial ignition timing via the stator plate, which affects the overall timing as a whole, to get even more variations. Yeah, you can kind of go down the rabbit's hole if you want to but that's something for someone looking to squeeze every last bit of power out of their engine. Personally, I leave mine set at the factory setting but a small change either way might make a huge difference on any engine. If I had access to a dyno I would probably see how deep that hole goes! :lol:
Slick_Nick wrote: 10:06 am Dec 19 2021 How much of a difference does it make, having an adjustable unit? I think a lot of us maybe don't know (because we haven't felt it) how much of a difference ignition timing can make on a two stroke like the KDX. I'm genuinely asking, all I've ever played with is rotating the stator plate, haven't seen what an aftermarket CDI could do. If it's something that's able to unlock some hidden power or tractability in the KDX, absolutely I'd be interested. I run race gas in all my bikes, so if this is something that would allow me to take full advantage of the higher octane, then you can put me down for one.
It does make a noticeable seat of the pants difference but it's hard to quantify other than better overrev on the 220. The things I noticed when running Jaguar's CDI was the increased throttle response and the engine just pulled hard and smooth throughout the entire rpm range in addition to the overrev. You played with the stator plate timing. Did you feel the difference at different points in the rpm range when riding it after advancing or retarding it? This CDI would basically do the same thing but allowing different ignition advance or retard in different points of the rpm range so you can really dial in what the engine wants.
Slick_Nick wrote: 10:06 am Dec 19 2021 If the cost / benefit ratio is hard to justify, then I think it may be a tough sell. I know you had yours fail on you far from home, some of the trails I ride are a good 50 miles from the truck, so this would be a concern for me as well. I guess I could keep the stock one as a spare in the backpack.
Yeah, it might be a tough sell. This is a mod that is probably more for those who really get in to this sort of thing, optimizing everything they can! I love trying to get my bike to be the best that it can be but I know most people aren't like that. The stock CDI does a pretty good job to begin with but there is always better.

The failure of the Jaguar CDI is something I kind of saw coming. While his electronics were awesome, his execution could have been better. See, the Jaguar CDI died due to nothing more than vibration. Here's a pic of the Jaguar CDI I bought...

Jaguar CDI.jpg
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The large orange-ish capacitor at the bottom is what failed initially as it broke it's leads at the circuit board. I didn't bother to remove the whole CDI from the bike when it failed and the next time I opened it up the IC chip had broken off as well. I even installed the CDI using a rubber insulator but it didn't stop the breakage.

Anyway, notice what's different between it and a what you see on a factory Kawasaki CDI? The factory CDI is potted and the Jaguar one is not. For those that don't know what potted is it means that the electronics are encapsulated in a special epoxy. That shiny black surface on the back of your factory CDI is the epoxy potting. The epoxy seals off the electronics from moisture and dirt, acts as a heat sink, and it protects the electronics from failure due to vibration. My CDI will be potted and the switches/jumpers will be the only things exposed (they will be water/dust proof) but still held by the epoxy so they don't fail due to vibration.

On worrying about it failing, well, like I said, I thought a failure was probably likely so I left my factory CDI mounted in place and mounted the Jaguar in another location. I didn't modify the factory wiring in any way so, when it failed, it was just a simple unplug one CDI and plug in the other and I was on my way riding again. The CDI I am planning to build will not suffer the same fate as the Jaguar CDI but electronics can and do fail at times. I would always recommend keeping the factory CDI mounted to the bike just in case of a failure. Of course, I do plan to offer a warranty on my CDI and, if it were to fail, I would either replace or refund at the owners request. I haven't figured out what my warranty policy should be completely yet but I am trying to figure it out.

I have some other ideas in mind in connection with this CDI but I'm keeping that under wraps for the moment. :cool:
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by doakley »

So you will be set up so you can vary the ignition timing within different rpm's. (I guess that's the whole idea behind "adjustable CDI" huh?)
I could adjust timing to my personal liking through low-mid and top end, right? In theory that would let me optimize power across the rpm range in that case. I think I like that idea, or at least enough to give it a try. Even though I'm no longer racing I like the idea of making my old KDX as "modern" and competitive with modern bikes as possible. If Kawasaki isn't going to build an updated KDX, by damn we can! I'm in. Put me on your short list.

(Somebody's going to get a hell of a KDX220 whenever I finally sell this thing!)

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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by Slick_Nick »

I have no doubts in your workmanship, and I'm sure you'll make a great unit! I would think that it would really be beneficial, if you allowed adjustment up to and maybe a bit outside of what you'd call a "safe range" to allow guys like me with a race cut head and high octane fuel to really take advantage of being able to advance the timing for more bottom end grunt.

When I played around with adjusting the stator plate, I noted that with it retarded, I picked up some over-rev, but I usually ran it full advanced, for the maximum amount of bottom end grunt - what the KDX is designed for.
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by SS109 »

Yes, this CDI will let you adjust the timing for the low to mid rpm range timing and then the mid to high rpm timing, from mild to semi-wild, LOL. It will make enough of a change that, depending on the parameters of your engine mods and fuel, you could get in to detonation and especially so if you advance the stator plate initial timing as well. However, if you're using good 91+ octane fuel, and leave the stator at the factory setting, for most it you should still be completely safe from detonation with almost any ignition curve you set it to.

All this said, I still have some R&D to do so it's still going to be a few before I have them done. I also want to get each one fully tested before any will be ready to go in to the wild.
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by SS109 »

:cool: Just an update. I have finished my pcb design and sent my files of them out to be made. The whole covid effect is playing out as some delivery times are pretty slow and a lot of parts are of limited supply. However, I got everything on order that I needed but had to go through several supply houses to get it all. I can't hardly wait to get the first one built and start testing. Woohoo! :boogie:
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by KDXGarage »

Thanks for the update!
Thank you for participating on kdxrider.net. :bravo:
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by MoonStomper »

If you send me one, I’ll test it and pay for it, just to help you get further along.
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by SS109 »

MoonStomper wrote: 11:19 am Jan 20 2022 If you send me one, I’ll test it and pay for it, just to help you get further along.
Sweet! I need probably a couple of people who ride a lot to really beat the snot out of the unit. I'll keep everyone posted as things move along.
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by SS109 »

Anyone else? I should have the first prototype done next week and be able to ship one or two out to some beta testers shortly thereafter.
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by Kawibunga »

Definitely interested but I need to put some km on my stock 220 first! My boys ride 220s, but it will be my first season on one. Going from a KLX650R. But can't believe Jaguar didn't pot his electronics. Even some RTV would be better then nothing. Very interested to hear the feedback from your beta testers! Cool project
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by SS109 »

Look what finally showed up today! Woohoo! :mrgreen:

cropped.jpg
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by Slick_Nick »

Oh dude! This is gonna be sweet!
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by Kawibunga »

That sure looks like it's going to be properly done!! Very nice!
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by SS109 »

Well, it looks like all my small parts made it through LA without being hijacked :mrgreen: and have made it to Phoenix. Hopefully they will arrive in the next day or two. :boogie:
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by Guffer »

I'm interested as long as it can be easily adapted to my '89. The price seems very fair for a quality 'Made in the USA' part and especially since you're available for tech support!
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by SS109 »

Thanks! Yeah, it will work on any '89 and up KDX but I have the wiring specifically setup for the '95 and up bikes connections and color coding. It is slightly different on the '89-'94 bikes. I will have enough wire length added on for various mounting location options and/or if the terminal ends need to be changed to plug to fit an the E-series bike. I don't remember if they use the same terminals and terminal layout as it's been too long since I had an E-series bike. However, I can provide documentation for matching up the correct color wires.

Oh, for you '88 and older KDX owners, this CDI will also work for you! There would need to be a few more changes (coil, wiring) to make it compatible with the earlier bikes but you can benefit from an adjustable CDI as well.

UPDATE: Sadly, while everything has gone well building the first prototype, the supplier listed one part incorrectly so I ordered a part that won't work with this CDI. After contacting them it appears I can't get it the way I want through them so I'm on the hunt to find suitable replacements. This setback really sucks as I would have had it done and started testing this weekend. Hopefully I'll have better news soon! BTW, here's a pic of the first prototype...


CDI prototype.jpg
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Re: Adjustable CDI for KDX 200 and 220- Interested?

Post by MoonStomper »

Setbacks are the name of the game, can’t tell you how often this has happened to me. Anymore I just expect things to be wrong when I order stuff. When I was a kid I remember being sooo excited to order something out of Boys Life magazine and then to get it and be disappointed with it’s form or function. … why I never ordered the hovercraft kit!

QUESTION… so the pink cdi that guy did has two tiny switches in his non-potted design. How are you going to set up your switches? My son’s 2008 KTM 144SX had an adjustable cdi that you had to pull the tank, find the harness, unplug one wire, and then plug in another. This softened the hit and gave better soft terrain traction. I liked it softer, but Henry liked it in ‘wild mode’ better so I bought some tiny red push button switches on Amazon and wired one in that I mounted under the tank for easy access. Problem was, it was kind of hard to tell which mode you were really in without hammering the bike. So it would be nice for this interface to allow you to just look at it and know.

Does this make sense? So what do you have in mind for mode changes? Let me know if I can help you model some practical ideas from a user-interface perspective. Something bar-mounted would be interesting to consider.
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