1990 KDX200 odd behavior - - possibly bad CDI?

Discussion specific to the 1989 - 1994 (E Series) KDX200 model sold in the USA
90SDKDX
Supporting Member
Posts: 181
Joined: 02:46 pm Aug 11 2012
Country:

1990 KDX200 odd behavior - - possibly bad CDI?

Post by 90SDKDX »

Hello all. I've been a member on here for quite some time but have not posted in quite a while.

Before I post my problem I would like to say I'm glad that BDK is now making the aftermarket KIPS valves in steel rather than aluminum. I believe I was one of the first members on here to post about the BDK racing valves back before they were making Steel valves.

Anyways enough of me trying to gloat about something I may or may not have done.

Here is my problem. I took my bike out for the first ride of the year last weekend. Shortly after leaving the truck there was a small point where I was giving it gas and the bike was trying to stall out. Before it stalled, while I was still moving, the bike picked up its momentum again and ran fine thereafter. Roughly an hour later we came to a stop and I stalled the bike trying to find neutral(oops). After this happened the bike did not want to start.

I pulled over to the side of the trail and checked spark, which I did have. I couldn't quite tell if it was blue or white or what color but spark was visible. I then removed the drain plug in the carb to check for gas, which I did. After this I kicked and kicked and kicked and nothing. Then my buddy gave it a go. Same outcome. Removed the spark plug again and kicked to see if any gas was spraying out, which there wasn't. Then I kicked again and again and it started. When it did start it was a very low idle that gradually picked up. If you gave it any throttle before the idle picked up it would stumble and die almost immediately. Also it would only start with the throttle completely closed. There was also a weird coincidence of if I either pulled in the clutch lever or turned my headlights on(Trail Tech X2) the bike would cutoff, almost like turning a key in your vehicle. I feel these were just coincidences and have nothing to do with the actual problem since it did not do this every time, but I could be wrong.

We got it started one last time and I rode back to the truck as fast as I could. Once back to the truck I killed the bike and started removing all my gear. I then tried again to start it and it was not having it.

I've been tinkering with it in the garage the past few nights after work and this I what I've done/found:

Cleaned Carb --- no visible gunk in carb (BTW I work at a dealership, that doesn't carry Kawi, so I have access to a great carb cleaner)--- reinstalled carb, bike still cuts out randomly
Replaced spark plug with new plug --- after idling bike for a while plug was not black nor brown but still looked new with a small amount of gas on it.
Ohm tested source coil of stator --- within spec
Ohm tested ignition coil --- Just outside of spec on primary side but I still had spark
Ohm tested CDI --- Many readings that were displaying open when there should have been resistance

To elaborate on the CDI testing I found that when testing the Black/Yellow wire, which is the one connected to the ignition coil, it was not showing continuity with any of the other wires that it should have.
What is strange here is if I follow the service manual pattern of negative lead on the Black/Yellow and positive on the other wire being tested, I get an infinite reading. However, if I switch these leads around I get resistance, but it is in Mega Ohms, which may as well be an open or close to it. Is there a one-way diode inside these? There were a couple other readings that were off as well, but this is the one that alarmed me most since it is part of the sparking system.

My confusion lies in the fact that if my CDI is testing bad, I should have no spark at all correct? I'm wondering if when I'm kicking the bike I'm creating enough of a jerking motion to make some sort of connection inside the CDI that allows it to function, until the connection is lost again or the bike is shut off. I don't really know what else to check at this point. My compression is on the lower end of the spec, but it is still within its specified range. I've seen other people on here have issues with the source coil that tested good when cold and bad when warm so I'm wondering if that should be my next step.

If this issue doesn't get sorted soon I may have to upgrade to one of our Betas we have here at the shop. :wink:

If anyone has any pointers for me I'd appreciate it.
eprovenzano
Member
Posts: 200
Joined: 12:00 pm Nov 21 2013
Country:
Location: Wellsburg, WV

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by eprovenzano »

This one is a tuffy... It sounds like erratic spark... If it starts and runs fine when cold, I'd lean towards the coil or stator. The only true way is to swap for good known parts until you find the correct one...

Where are you located, perhaps you're close enough to one of us to compare / swap parts so you can find the problem.
1991 KDX basket case... being rebuilt
2001 KTM EXC 380... two stroke heaven
2000 KTM EXC 300, son's
1993 Kawaski Bayou 400 4x4
2008 Yamaha Vstar 1100 Silverado
90SDKDX
Supporting Member
Posts: 181
Joined: 02:46 pm Aug 11 2012
Country:

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by 90SDKDX »

I'm in western South Dakota.
eprovenzano
Member
Posts: 200
Joined: 12:00 pm Nov 21 2013
Country:
Location: Wellsburg, WV

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by eprovenzano »

Sorry I'm near Pittsburgh PA... just a little too far... lol
1991 KDX basket case... being rebuilt
2001 KTM EXC 380... two stroke heaven
2000 KTM EXC 300, son's
1993 Kawaski Bayou 400 4x4
2008 Yamaha Vstar 1100 Silverado
User avatar
Jaguar
Supporting Member
Posts: 590
Joined: 01:32 am Jul 03 2013
Country: Paraguay
Location: Paraguay
Contact:

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by Jaguar »

ignition problems usually act like an on/off switch, nothing gradual.
you said "it would only start with the throttle completely closed" which points to the carb jetting as the problem. check to see if the idle jet is clogged.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
90SDKDX
Supporting Member
Posts: 181
Joined: 02:46 pm Aug 11 2012
Country:

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by 90SDKDX »

eprovenzano wrote:Sorry I'm near Pittsburgh PA... just a little too far... lol
Go Penguins!!

I emailed Jeff Fredette this morning and he replied back to me saying it is more often the source coil than the CDI at fault. It will test good when cold and bad when hot. When I get home tonight I will hook everything back up, make sure I have spark(confirming my CDI is actually fine and not bad), and then let it run for a while. Once it's warm I will test the source coil resistance again and see if anything changes. I'd much rather have it be this part than the Cdi since its about half the price. It will give me a chance to JB weld my porous crankcase as well since it seems to seep like most of the early E series machines.

I will let you know what I find after my test tonight.
90SDKDX
Supporting Member
Posts: 181
Joined: 02:46 pm Aug 11 2012
Country:

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by 90SDKDX »

Jaguar wrote:ignition problems usually act like an on/off switch, nothing gradual.
you said "it would only start with the throttle completely closed" which points to the carb jetting as the problem. check to see if the idle jet is clogged.
When I cleaned the carb I made sure that my idle jet was perfectly clean and that I could see through every orifice. This was my first inclination as well.

I should also say that when I had it running in the garage the other day it did start with throttle when it was cold(stalled once just after start up), but once it was warm it didn't want to start again after it died.
90SDKDX
Supporting Member
Posts: 181
Joined: 02:46 pm Aug 11 2012
Country:

1990 KDX200 odd behavior - - possibly bad CDI?

Post by 90SDKDX »

Alright everyone I put the CDI and ignition coil back on tonight. After re-assembly I still had spark so that was good. I did another resistance test of the source coil for reference. It was around 356 ohms. I hooked up a reserve bottle of fuel and started the bike after a few kicks. I let it idle for a while in the driveway to get it warmed up. It never died on me but it did almost cut out a couple of times while I was shaking the bike around. This may have been coincidental. I let the bike get "warm" and killed it. I then re-checked the source coil resistance and it did increase to .457 Kilohms (so 457 Ohms) which was still in spec, but nearly 100 ohms higher.

This leads me to believe that the source coil is a possible fault. Even though I didn't find an open in the circuit I still don't believe the resistance should be rising this much.

At this point I don't know what else could be causing the bike to simply die without any telltale signs.

If anyone has any other ideas or input please let me know.
eprovenzano
Member
Posts: 200
Joined: 12:00 pm Nov 21 2013
Country:
Location: Wellsburg, WV

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by eprovenzano »

I too believe it's the coil. The resistance shouldn't have changed as much as it did.


Sent from my iPhone using Tapatalk
1991 KDX basket case... being rebuilt
2001 KTM EXC 380... two stroke heaven
2000 KTM EXC 300, son's
1993 Kawaski Bayou 400 4x4
2008 Yamaha Vstar 1100 Silverado
90SDKDX
Supporting Member
Posts: 181
Joined: 02:46 pm Aug 11 2012
Country:

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by 90SDKDX »

I ordered the source coil this morning from Ricky Stator. Hopefully I will see it this coming week so I can install it and make sure everything is running properly. I'm anxious to get out again.
User avatar
Jaguar
Supporting Member
Posts: 590
Joined: 01:32 am Jul 03 2013
Country: Paraguay
Location: Paraguay
Contact:

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by Jaguar »

that's the good news. the bad news is that the new coils voltage is higher than stock which causes a timing advance.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
90SDKDX
Supporting Member
Posts: 181
Joined: 02:46 pm Aug 11 2012
Country:

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by 90SDKDX »

How do you know this? According to the website and everything I've read it is close to a oem coil.
How would this create a timing advance? Is that not controlled through where the stator plate is positioned?

If it is indeed advancing the timing, how will this affect the bike? Will I need to retard the timing with my stator plate position to compensate for this?
Friedom
Supporting Member I
Supporting Member I
Posts: 803
Joined: 08:46 pm Nov 22 2015
Country:

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by Friedom »

I concur that your stator could be culprit.
I have a 93 that had a ton of parts replaced before I got it. Couldn't get it to kick start. Could bump start it on my steep driveway though, and nurse it along until it would idle. Never ran well, was awful at anything but idle. Died randomly. After verifying carb, coil, cdi, and plug on my running 92, seeing good compression and good spark, I tested the coil resistance and got about the same as you did. 370 ohms iirc.
Since everything else was narrowed out though, and I discovered there was no lighting coil, I picked up a used stator from a running bike on ebay, installed it and she fired right up and ran great (except for a broken KIPS valve, of course).
Cylinder is getting repaired and plated now, BDK valves ready to go in and a new wiseco.
I see no way that the replacement stator could advance timing, though.
Please let us know if the stator fixes it!


Sent from my SM-G930V using Tapatalk
User avatar
Jaguar
Supporting Member
Posts: 590
Joined: 01:32 am Jul 03 2013
Country: Paraguay
Location: Paraguay
Contact:

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by Jaguar »

most CDIs have a trigger coil that gives the circuit a reference point in time. This CDI doesn't. When the negative voltage from the stator coil reaches a certain level inside the CDI then it fires off a spike of voltage to the final coil which amplifies it. The voltage from the stator coil is a sine wave with the voltage rising to a peak at its 90 degree point from where the sine wave started (and opposite voltage peak at 270 degrees). Up to that peak voltage it is rising, it's level is time dependent. If the replacement coil outputs higher voltage then it reaches the "trigger" level of voltage earlier, thus creating advanced timing. You should be able to correct for it by rotating the stator coil plate CCW. If at maximum rotation it is still too advanced then you will need an adjustable CDI to bring it back to normal.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
90SDKDX
Supporting Member
Posts: 181
Joined: 02:46 pm Aug 11 2012
Country:

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by 90SDKDX »

Jaguar wrote:most CDIs have a trigger coil that gives the circuit a reference point in time. This CDI doesn't. When the negative voltage from the stator coil reaches a certain level inside the CDI then it fires off a spike of voltage to the final coil which amplifies it. The voltage from the stator coil is a sine wave with the voltage rising to a peak at its 90 degree point from where the sine wave started (and opposite voltage peak at 270 degrees). Up to that peak voltage it is rising, it's level is time dependent. If the replacement coil outputs higher voltage then it reaches the "trigger" level of voltage earlier, thus creating advanced timing. You should be able to correct for it by rotating the stator coil plate CCW. If at maximum rotation it is still too advanced then you will need an adjustable CDI to bring it back to normal.
That makes some sense. Have you used these coils before? I would imagine if the resistance is similar to the old one it wouldn't cause too much of a problem. How would one go about telling if the timing has advanced? I know motors that are too far advanced will begin to knock. What is the farthest you can rotate the stator plate?
90SDKDX
Supporting Member
Posts: 181
Joined: 02:46 pm Aug 11 2012
Country:

1990 KDX200 odd behavior - - possibly bad CDI?

Post by 90SDKDX »

Well I took the stator off tonight in preparation of putting the new source coil on. Everything inside looked fine as far as my seal so that's good. Source coil "looked" okay and I put some JB weld on the crankcase where they are known to be porous.

I'm hoping the new source coil has the wire and connector all attached so I don't have to solder anything. My soldering skills are horrible.
User avatar
Jaguar
Supporting Member
Posts: 590
Joined: 01:32 am Jul 03 2013
Country: Paraguay
Location: Paraguay
Contact:

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by Jaguar »

I've heard from others that the Rickystator coil is like that. I just had my own rewound locally.
Advanced give more mid range but less top end power.
Performance CDI -- KDX motocross mods -- the SR KDX -- expansion chamber analysis---> http://www.dragonfly75.com/moto/
90SDKDX
Supporting Member
Posts: 181
Joined: 02:46 pm Aug 11 2012
Country:

1990 KDX200 odd behavior - - possibly bad CDI?

Post by 90SDKDX »

Well Jaguar I am afraid you are correct. Tonight I got home from my camping trip and installed the new source coil. After a sub-par solder job I got the new coil mounted on the stator base and got everything installed. I was so excited to hear my baby run again but nope!

I tried everything I could think of to get it running and I had no luck. I have fuel, spark(first thing I checked!), and compression. There is nothing in the air filter that would be blocking air flow. My spark plugs were coming out wet, but not discolored(I tried three different plugs to be sure). I also tried different air screw settings and turning the idle screw in with no success, which I expected.

Right away I noticed one thing in particular. When kicking the bike over the kick starter would kick bad HARD!! My bike has never done this and man does it hurt when kicking it over in shoes(Stupid I know). I know that advanced timing has this side effect.

I took the magneto on and off probably 5 times, each time trying different timing settings on the stator. I had started at the stock setting, then slightly advanced, slightly retarded, then fully retarded and fully advanced. Each time nothing seemed to change much. The bike would sometimes get that grumble sound like it wants to start, but would never pick up RPM.

After kicking and kicking and kicking I gave up. I think at this point I will need to order your CDI Jaguar. My only other option would be sourcing an OEM source coil, but I would be throwing away 60$ on this coil, plus having to re-wire everything again. How long does the shipping take on your CDI? Will it be a complete plug and play or will I need to change some of the connections?

I'd still appreciate anyone's input. If you think it may be something else, please let me know. I hate to be down much longer since riding season is getting near perfect here.
90SDKDX
Supporting Member
Posts: 181
Joined: 02:46 pm Aug 11 2012
Country:

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by 90SDKDX »

Hey Jaguar I pushed an order through for your CDI this morning. When I receive it, should I set the mid-range setting to low to try and offset the advance that the source coil is creating?

I'm really hoping this fixes my issue.
sthoward
Member
Posts: 41
Joined: 06:01 pm Nov 24 2015
Country:

Re: 1990 KDX200 odd behavior - - possibly bad CDI?

Post by sthoward »

I bought a non-running KDX E series that showed very similiar symptoms to yours. I got a new stator coil from rmstator.com and she worked right away. No problems with advance, I just re-mounted the stator plate in the same position it came off and kicked it 2-3 times and away she goes.

Not sure why the Ricky Stator part wouldn't work for you, I've never tried it myself.
Post Reply