KDXRIDER.NET

I'm curious to know if there's anything I could add to the transmission of my '87 without harming the clutch pack that I could run for a few minutes before changing the oil that would aide in cleaning the old goo/crud from the clutch pack and transmission case? I was thinking of a small amount of sea foam or something to douche everything off, then drain it and add fresh oil. I am having an issue with sticky clutch plates. I changed the oil a few months ago with the correct oil because of sticky plates and have had about half a dozen rides since. The old oil was pretty grubby. The clutch still seems a bit sticky.
Backstory on the bike, bought it from the original owner (my uncle). I don't know how often if ever he changed it. The clutch doesn't slip while riding or anything abnormal, but if the bike isn't running and it's in gear and I pull in the clutch it doesn't want to roll unless I put it in neutral.

"if the bike isn't running and it's in gear and I pull in the clutch it doesn't want to roll unless I put it in neutral"

That is 100% how it is supposed to be. My various dirt bikes do that. You are not the first to post that. Does a manual transmission car do it? I have just driven automatics. I am curious why people have thought this over the years.

This is not related to that, but I suggest you change the oil, then ride for a while, change the oil until it seems to clear up. Of course, the shock and forks need new oil, too. Grease all the suspension linkage. Most of it has grease fittings.

Pretty normal for KDX's to not want to roll in gear with the clutch pulled. I would suggest pulling the clutch, checking the frictions and steels for wear and the basket for notching, then reassemble, add oil and ride. Drain it immediately while still warm and repeat until you're happy.

Well this has turned into something odd. I added a small shot of seafoam trans tune into the transmission. I fired it, ripped up the street, turned around and the bike began to act like I was jogging the kill switch. Got it back to the house and discovered I lost spark. Fortunately I have the original shop mamual so following the test procedures I was able to determine the cdi box died. Found one on fleabay new old stock. After I sold my kidney I was able to acquire it. Installed and now have spark. Assembled the bike and fired it off. It was acting odd though. Idled but dogged out and died each time any throttle was given, even slightly off idle. Issue aside, this is a very clean bike. Fuel system is clean and operates normally. I'm concerned the seafoam did something bad to a crank seal. Had to stop working on it for the night. Pretty frustrating, my kid is here for the week and riding was a big part of our plans.

Check the transmission oil level to see if drops due to leaking out through a worn seal. Even if new in the unopened shipping crate, it is still made in 1986, so 38 years old.

Well good news, it's not a crank seal and the bike is now up and running. A little embarrassed to say what the issue seems to have been, but I guess the sparkplug was worse than I had thought it looked. After installing a new plug one step hotter, she lit right up and reved like it always had.

Better to have an embarrassing cheap fix than a solidly known expensive one.

Are you now using an 8 heat range plug?

KDX-G said above, "Better to have an embarrassing cheap fix than a solidly known expensive one."

I 2nd dat!

Yep, went with the 8

Cool, sounds good. I once went from fouling plugs once a day to once a month when I went from a 9 to an 8.

I recently installed a DG pipe. I just got back from my first ride with the new pipe and spark plug. Now I need to pull the plug and take a reading to see how it's burning. The paperwork that came with the pipe stated a re jetting may be needed. So we'll see...

Have you ever addressed the issue of aging KDX200C flywheel magnets self destructing?

I was worried that was what might've caused your CDI failure.

Please look into this if you have not yet. The magnets are not fully encased in epoxy as most others are, and they will become stressed with age and let go and obliterate everything under the flywheel (both stators etc). The solution is to extensively clean and degrease the flywheel rotor magnets area, dry, and mix up a large batch of epoxy to methodically fill in the gaos between the magnets and fully encase them.
Or else ditch the entire stock electrical system for an aftermarket PowerDynamo / Vape (vape.eu or their US distributors) setup, or swap a 95-06 KDX stator plate, stators, ignition coil, and CDI (I'd go for an 89-94 CDI personally, more broad power curve). The 95-06 stator plate fits but the holes are approximately 90 degrees out of time, so new slotted holes need added 90 degrees approximately from the existing 3-hole slotted pattern. I can't tell you any further specifics, but that is discussed on this forum elsewhere.

I've never had the privilege of owning an '86-'88, but they are a dream machine of sorts for me, being the last and best air cooled bike for Eastern woods riding....

I've owned 4 86-88 KDX's (sold 1). 2 had ruined stators when I got them from when a magnet fell off the flywheel. My other 2 haven't been started in years and I won't start them until I fix the potential flywheel problem. I've got one 87 that I do ride around my house every now and again. It has a stock used stator and flywheel I got off ebay to replace the destroyed original. I know I'm on borrowed time with the one I was lucky enough to find - it could destroy itself at any moment (again!)

I think I will try the epoxy trick one of these days. I bet the 89 and newer flywheels will be a little heavier from the increased horsepower of those engines, and I do not feel that the 86-88 KDX's need any more weight than they already have. They rev pretty slowly. So.... I guess I'll have to learn about epoxy before I destroy my 87.

I second Chuck78's recommendation. If you don't reinforce your current flywheel's epoxy, at least be prepared to piece together a different system when it does blow. And maybe avoid taking it on long rides into the wilderness until you address the issue.

Chuck78 - the C-series KDX is truly my favorite old bike to ride back in the woods of Pennsylvania where my family mostly still lives. Out west here in Washington they are still great bikes, but for slick, tight trails back East, they are fantastic. Low to the ground, light, comfy seat, and great layout for my 5'10" legs and arms. I have an 85 KX250 seat on it that slims and lowers it even more. And power that will tractor along through all the slop and logs, yet rip down the straight when the trail opens up. That KIPS is a great invention! I'm sure you'll get one someday. Out west here they seem to be for sale all the time and they don't seem to be worth much compared to other 80's bikes like the IT's. I think it's their slightly homely looks holding them back. All the better for us I say :-)

A friend and I bought an '87 back in 2002 for him to ride. After a few months, the rotor disintegrated on him.