Adjustable CDI for KDX 200 and 220- Interested?

[SS109]

LOL! Yeah, I know I'm an old curmudgeon. Now, get off my lawn!

Thanks for the compliment on the CDI. I know it came out pretty nice looking but the proof is in the pudding. I really gotta get out and test it on the trail.

[hi-def]

Nice work on the CDI's, those pcb's look very smart.
I put one together last year for a bit of fun, was quite satisfying seeing it run. I used what was available at my local electronics shop and a few components weren't rated correctly so I built a second version with a few extra bits and some adjustment like yours.
Version 1


Version 2

[SS109]

Nice! I like seeing others take on projects like this. It's challenging (at least for me it is!) but so rewarding!

BTW, everyone, here is a pic of the instructions I drafted up tonight for my CDI. Is it easy enough to follow? Does it make sense?

ATTENTION: If you downloaded the previous instruction sheet please delete it and replace with the one located later in this thread. The original had errors on which switch positions affected which area of the Low-Mid curve! The doubly incorrect version has been removed and the corrected version has been added in a post below.

Latest updated instruction sheet: download/file.php?id=4980

[MoonStomper]

Very well done. It even makes sense!

[Kawibunga]

That's awesome SS109! 16 different curves should have a combo for everyone. For people that like to tweak it will be like a kid in a candy store! And great that you guys got to meet. I've been on forums where you feel like you've known a guy for years just through the forum interaction all though you've never actually met. I'm pretty new here but this seems like on of them too, which is a great thing.

Definitely interested in a testing report from Slick_Nick, be great long weekend up here for some cold weather testing opportunities, with rain and snow and -25°C in the weather forecast! But I think I'd be enjoying the AZ sunshine for a while first :)

[Slick_Nick]

That's awesome SS109! 16 different curves should have a combo for everyone. For people that like to tweak it will be like a kid in a candy store! And great that you guys got to meet. I've been on forums where you feel like you've known a guy for years just through the forum interaction all though you've never actually met. I'm pretty new here but this seems like on of them too, which is a great thing.

Definitely interested in a testing report from Slick_Nick, be great long weekend up here for some cold weather testing opportunities, with rain and snow and -25°C in the weather forecast! But I think I'd be enjoying the AZ sunshine for a while first :)

Well, I won’t pull the bike out if it’s quite THAT cold, but I think once it warms up, I’m going to take it to the motocross track first. The reason behind that is threefold; it allows me to stay close to the truck, just in case I get a little “greedy” with the timing and cause myself some headaches , it allows me to get quantifiable data on what each change is doing exactly, since I can repeat the terrain and conditions perfectly lap after lap, and third, it allows me to stay close to the truck again so that I can mix up perhaps two different batches of fuel and try them out (to keep the test fair, I would run each tank until the bike quit, and I don’t want to push it too far back to the truck.) I normally run 100 octane leaded fuel, but since the bike and carb were both completely drained and cleaned before I put it into storage for the winter, I could mix up a small batch of 93 octane pump gas and see how much difference the higher octane leaded fuel makes in comparison.

Super excited to get to try this thing out!

[doakley]

Sitting back waiting for Beta testing so I can get one too!

[John_S]

It’s great that you and Nick got to meet and talk about the bikes over food. Two KDXrider hall of famers. Thank you SS for the time and effort in making our old bikes as good as they can be. I’m looking forward to hearing about your testing.

[SS109]

Nick tried to contact me yesterday about how much advance this CDI produces over stock. It was really late before I noticed his text so I haven't had a chance to reply to him yet but thought the info would be, maybe, of some importance to those interested in my CDI.

On the Low-Mid settings, if my calculations are correct, my CDI should give you 4 degrees more total advance (in 1 degree increments) across the entire rpm range at it's most extreme and about 30 degrees max advance @ 3000rpm. I know it doesn't sound like much but on a two stroke but 1 degree makes a noticeable difference that you can feel.

The Mid-High retard timing will adjust total timing down to approximately 10 BTDC on all settings starting at 3000rpm but how fast that happens is what each position controls.

Position "0" - will provide the most gentle curve and reach 10 BTDC at approximately 9800rpm.
Position "C" - same timing at approximately 8500rpm
Position "3" - same timing at approximately 7000rpm
Position "F" - same timing at approximately 5500rpm - the most aggressive retard timing

Now, why I say "approximately" or "should" when talking timing specs. Several factors come in to play that can affect the timing that I have no control over. Things like your source coil's condition, whether OEM, aftermarket, or you roll your own , your ignition coil, it's condition and whether OEM or aftermarket, and even your lighting coil can change things. That's why I have tried to make this as easy as possible allowing for those different factors along with all the other things that affect engine performance like pipes, porting, head squish, etc. It's really pretty much impossible to build an analog ignition system that can do it perfectly for everyone. However, I truly believe that this CDI can benefit anyone in getting more power, better fuel economy, and/or better traction depending on the setting you choose.

If there are any more questions, please fire away!

ATTENTION: If you downloaded the previous instruction sheet I posted, please delete it and replace with the corrected one now inserted in to a later post or in the link below in this post. The original had errors on which switch positions affected which area of the Low-Mid curve! The incorrect version has been removed (again!)and the corrected version has been added in it's place.

Latest updated instruction sheet: download/file.php?id=4980

[SS109]

Test Day #1

I put roughly 22 miles on my CDI today. Thing ran great with no hiccups from the CDI.

I started out with full advance on the Low-Mid and base retard on the Mid-High timing. The bottom end had a substantial power increase and pulled very hard. IMO, too hard and I ended up at position "3" on both switches and felt that gave me more power throughout the entire rpm range without being too explosive off the bottom end. It would lift the front with ease, drive in sand was excellent, and top end pull was improved. I'm very happy with the results. Still need to abuse it quite a bit more before I decide they're ready for prime time. Hopefully things keep going well and my beta testers have the same experience.

BTW, for those talking about where to mount the CDI, here is what I did and a quick and dirty bracket. As you can see I can access the switches without removing anything and the only tool needed is the tiny screwdriver for adjusting the switches. I plan to remove it later, and either paint it or plastidip it. I made the bracket out of a Tubliss tire install helper tool since I have a few of them around. It is mounted on the left side of the bike just behind the fuel tank and in front of the side plate. When I get my latest vid up you should be able to see it easier.

20220220_211213crop.jpg (143.19 KiB) Viewed 15624 times

[MoonStomper]

Definitely could have used it in the race yesterday. Grease over ice conditions, steep short climbs and long steep WOT climbs on rocky dozer tracks! 13/46 gearing was the ticket though, got me through some sketchy places without spinning out and going down.

[Slick_Nick]

Awesome! Great to hear! I can't wait to get out and try this thing once the snow melts!

[DonnyV]

I just wanted to note the instruction sheet says "0" is the base timing on both switches but the picture says "0" is full advance, maybe a typo.

[SS109]

I just wanted to note the instruction sheet says "0" is the base timing on both switches but the picture says "0" is full advance, maybe a typo.

Good catch. I forgot to update the wording as well. I'll correct that today.

[SS109]

Ok, I hope I got everything correct now. If you spot any errors please let me know! Thanks Donny for catching the one I missed!

CDI instructions Corrected4.jpg (546.51 KiB) Viewed 15596 times

[SS109]

My vid showing where I located the CDI and me riding with it. I show the CDI mounting at about the 2 minute mark.

[SS109]

Just an update on where I'm at.

I've looked in to what I have in to making each CDI and I will be doing them for $120 USD shipped via USPS in the lower 48 states. If you live in Alaska, Hawaii, Canada, Europe, or elsewhere, you'll need to contact me to figure out what the additional shipping will be. All import duties, VAT, taxes or fees will be sole responsibility of the purchaser.

I will have only 17 available for purchase as 3 (Nick, MoonStomper, and myself) are already spoken for. I honestly don't know if I'll make any more of these, as they are pretty labor intensive, unless the demand is really there. So, if you're really interested please get in touch with me to reserve one. They still are probably a month out but I'm moving as fast as I can. I still need to get MoonStomper's CDI sent out so he can help with the beta testing so that I feel these are good to go.

[doakley]

SS109, I’m in. Tell me how to pay you!

[John_S]

SS, put me on the reserve list also. I'm not in a hurry for it so other guys CDI's could ship out before mine. I'll PM you later about payment.

[SS109]

Done and done!