KDXRIDER.NET

hello, i haven't posted yet so i wanted to introduce my self and ask a question about an issue im having with my 91 kdx250. i am working through the list of changes you guys recommend with the performance of the bike. i have the jetting/needle pretty dialed in i think and the .26 head gasket is on the way. it runs great from idle to about 3/4 throttle. the problem i am having is under heavy accel and at 3/4-wot it feels like i have a rev limiter on it and it cuts out during that throttle range. it almost feels like its misfiring under load as if i have an ignition issue. i tested my coil per the manual and it is reading almost 10k ohms when specs say 6.3k ohms +-20%. i am looking into getting a coil from ebay to swap out and checking all my grounds and wire connections. is there anything else that might cause this kind of issue? i spent a few hours yesterday messing with jets and needle clip positions and that issue didn't change during that process. thank you in advance for any help.

spark plug or plug wire. muffler carboned up.

tried a few new plugs, cleaned and repacked muffler a few weeks ago. thanks for the reply

I'm thinking you are running out of gas, or air....
Your float may be set to low and you are using all the fuel in the bowl before it can be replaced? There is some sort of blockage between the carb and fuel tank. Or the vent hose on the fuel tank is collapsing.
Are you using a new air filter? Are the reeds in good condition?

cbsmarty23 wrote:tried a few new plugs, cleaned and repacked muffler a few weeks ago. thanks for the reply

Did you try a new plug WIRE?

i set the float level according to the manual but ill check it again. there is a little fuel filter in the fuel line from the tank to carb, ill replace that. ill crack the cap loose and ride it and see if that changes the issue. yes airfilter is new. removed the reeds and they look in good condition, i believe they are stock though. i am looking into getting a coil and wire on ebay. by new wire do you mean the end? as the wire is part of the coil? thanks

so i got a look at the coil and wire today, i found out the wire comes out of the coil. i tested the coil again and it is right at specs about 6k ohms. the wire is 0 ohms and the end is 4k ohms, i think i found my problem in the wire end. can i use a regular car plug wire end or do i need to get a special one for motorcycles? thanks again for your help!

Sorry for all the questions, I thought the cap was the issue but I guess it is supposed to have a resistor in it? Does anyone know the specs on just the cap?

not sure what is standard for the KDX but most of those type ignition systems can have or not have resistance in the plug cap or the spark plug. I prefer the only resistance being in the iridium spark plug I like.
It is true that the higher the RPM, the less voltage the CDI accumulates to use with the high voltage coil to make the high voltage going to the plug. (Also at low low RPM such as when you are kickstarting it and when it is idling). So if something is impeding the current flow, such as corrosion at the stator coil plate (which is part of the ground path), it will be at high RPM. Clean where the screws press against the stator coil plate to hold it in place.
Could also be that it's time to replace the CDI. I sell an adjustable CDI for the KDX in case you decide that is the problem.
http://www.dragonfly75.com/moto/fixing-ignition.html

update: i put a coil and wire on the bike but the issue is still there. i also checked the float level and its right. cracked the gas cap while riding, no change. after riding it more and marking the throttle it seems like it has the issue at 3/4 throttle and after a couple seconds at wot it clears out. i have messed with the needle, clip position and jetting and it didnt seem to affect the issue. it feels like its cutting out at a certain rpm or load range just like a ignition miss. im thinking about the kips system being an issue? it runs great at all other throttle areas/conditions. any other thoughts are greatly appreciated

Have you inspected the reeds yet? A small crack will give you bogs.

I have, I believe they are original but in good shape. It more like hicups or misfires or cutting out at that throttle angle or rpm.

CDIs don't last forever

jaguar, do you sell a cdi unit for my kdx250? i looked at all your info and all i could see was for the kdx200?

Also jaguar, do you have a way to test the cdi before condeming it without the special kawasaki tester?