Kx200x wrote: 12:48 am Sep 27 2025
I ordered this cdi box from Jaguar and if your serious about your kdx it will make a significant improvement. I have a 99kx125 E series hybrid. 36.5mm pwk with homemade divider plate, boyeson reed cage, and a platinum pro circuit pipe from an h series with kx 250 silencer, 08 crf450 coil. I like riding MX and single track woods loops. I had a 2018 beta 300rr race edition as my last woods bike and you could be chugging at close to idle and when you opened the throttle fully it wouldn't hesitate. It would just pick up and go without spinning the tire unless you got on the pipe. After installing Jaguars cdi the bottom end had a substantial improvement and I noticed the same effect. I could be crawling through a tight section in second and just open the throttle full and the bike wouldn't hesitate just got moving. I also felt it helped the midrange and top end as a trail I was previously ringing it out at the top of second I was now in 3rd gear in the midrange and It pulled very well. With the switches that adjust the timing to retard it at higher rpm I noticed it definitely picked up some over rev and could hold a gear longer. Seemed to provide a stronger spark as well because when I went to shut the bike down I let off the kill switch when it would have normally shut the engine off but it started back up so now ive got to hold the kill switch down longer. If you have the newest kdx your cdi components are 20 years old. Lost of advancements have been made in electronics over the past 20 years. Definitely recommend getting one if you love your kdx you will be glad you got it.
Thank you for your report back on that. That's about what I expected to hear, although I believe it's LESS of a performance increase going from the E-Series CDI as the 200E CDI has more initial advance than the H-Series CDI, so this is pleasing to hear that you're boasting about such a significant performance increase over the KDX200E CDI
I'm curious if you are also running the 1999-ish Honda CR ignition coil upgrade as well?
Jaguar recently began upgrading some of the output components in his CDI to better handle the higher output of that Honda coil which has the same mounting pattern distance as the KDX coil. I picked up one of these to run on mine when I do a major rebuild hopefully this winter now. I'll probably order another also.
Very interesting stuff here. I didn't know that an adjustable CDI could make such a big difference. I may look into that eventually.
I do have one question, not so much related to the main topic, but I've seen it thrown around a few times. What difference does a CRF450 coil make on the KDX? I own an 04 CRF450R (They're pretty similar bikes until the changes in '09) and have a spare coil for it, so if it's worth throwing on the KDX I definitely will.
Once I get my bike running correctly with this Lectron I may look into the CDI. Some really interesting stuff here.
92 KDX200
04 CRF450R
05 CR125R
~Don't mind me, I can be a little slow
Jaguar claims the Cr coils produce better spark. The 08crf coil is the same size as the kdx. Tbh I had just installed the cdi and definitelyfelt an improvement. I was refitting my silencer and had to take the pipe off and noticed scoring and the powervalve over clocked. I ended up having to rebuild the top end. I have a kx/kdx hybrid. So I found a video of a ported cylinder and did my best to copy it and polished the powervalves and got them times correctly. Polished the exhaust port and left the intake rough. I Imagine it will be drastically different once I reinstall the motor.
Last edited by Kx200x on 02:52 am Oct 11 2025, edited 1 time in total.
Kx200x wrote: 01:08 am Oct 09 2025
Jaguar claims the Cr coils produce better spark. The 08crf coil is the same size as the kdx. Tbh I had just installed the cdi and definitelyfelt an improvement. I was refitting my silencer and had to take the pipe off and noticed scoring and the powervalve over clocked. I ended up having to rebuild the top end. I have a kx/kdx hybrid. So I found a video of a fredette ported cylinder and did my best to copy it and polished the powervalves and got them times correctly. Polished the exhaust port and left the intake rough. I Imagine it will be drastically different once I reinstall the motor.
I'm curious about that, is there any chance you could provide a link for the video of the critiquing/outlining specifications of Fredette's porting job?
I just caught a quick glimpse of it and I bought a cylinder of ebay unkowingly that had a damage to the main exhaust port so I took a risk. I bought a 100 piston and ebay gasket kit and figured if it turned out badly I wouldnt lose my shirt. My cylinder that was unmolested but had the nikasil worn will be sent to Jeff for the real treatment when the time comes. I will be using an IMD cast pistons as with cars and now bikes have not had good luck with forged. IMD is in England and the pistons are built in Japan, cast and have 4 holes drilled on the exhaust side for cooling and lubrication. They come in .25mm increments so mine is like 199.95cc now lol
Kx200x wrote: 12:48 am Sep 27 2025
I ordered this cdi box from Jaguar and if your serious about your kdx it will make a significant improvement. I have a 99kx125 E series hybrid. 36.5mm pwk with homemade divider plate, boyeson reed cage, and a platinum pro circuit pipe from an h series with kx 250 silencer, 08 crf450 coil. I like riding MX and single track woods loops. I had a 2018 beta 300rr race edition as my last woods bike and you could be chugging at close to idle and when you opened the throttle fully it wouldn't hesitate. It would just pick up and go without spinning the tire unless you got on the pipe. After installing Jaguars cdi the bottom end had a substantial improvement and I noticed the same effect. I could be crawling through a tight section in second and just open the throttle full and the bike wouldn't hesitate just got moving. I also felt it helped the midrange and top end as a trail I was previously ringing it out at the top of second I was now in 3rd gear in the midrange and It pulled very well. With the switches that adjust the timing to retard it at higher rpm I noticed it definitely picked up some over rev and could hold a gear longer. Seemed to provide a stronger spark as well because when I went to shut the bike down I let off the kill switch when it would have normally shut the engine off but it started back up so now ive got to hold the kill switch down longer. If you have the newest kdx your cdi components are 20 years old. Lost of advancements have been made in electronics over the past 20 years. Definitely recommend getting one if you love your kdx you will be glad you got it.
Thank you for your report back on that. That's about what I expected to hear, although I believe it's LESS of a performance increase going from the E-Series CDI as the 200E CDI has more initial advance than the H-Series CDI, so this is pleasing to hear that you're boasting about such a significant performance increase over the KDX200E CDI
I'm curious if you are also running the 1999-ish Honda CR ignition coil upgrade as well?
Jaguar recently began upgrading some of the output components in his CDI to better handle the higher output of that Honda coil which has the same mounting pattern distance as the KDX coil. I picked up one of these to run on mine when I do a major rebuild hopefully this winter now. I'll probably order another also.
Running 2008 crf450r coil. It has the same holes as the kdx e eseries and same resistance measurements. Was gonna use a coil on plug from a zx14 but he advised me against it. I put it after the cdi Install ported top end rebuild. I think the cdi will help the H series just as much as a E series. 2006 kdx is 20 years old. 20 years old transistor, resistors, capacitors, diodes.
