1985 KDX 200 starting issues

[willub]

I just picked up an 85 kdx 200 from a friend for free. It ran really well for a while but then it started randomly dying on him and running terribly. Now it wont start. What is the compression supposed to be on these? im guessing 150ish. I got 110 out of it but didn't kick it over really well. I'll get a better number tomorrow.

I'm new to dirt bikes but I've been working on sleds and cars for as long as I can remember. Carb is cleaned and in working order. Reed petals are fine. Seems like the stator to me and I know they had problems. It would roll start before I got it but now it wont. It will fire a couple times while rolling but wont keep firing.

Any help would be great thanks.

 

[sr5bidder]

you may want to pull the stator cover and flywheel of and check the magnets on the flywheel...if they are intact you might want to re-epoxy them, earlier kdx's are known to throw magnets.

while your in there check out the stator windings and fly wheel key.

give the carburator a good cleaning too.

 

[dirt bike dave]

I can tell you from first hand experience stator failure is common on '83 - '85 KDX200's.

When mine failed back in the day, it started out being heat sensitive (bike would die when it got hot, then not restart until it cooled down a little).

Then it got worse - hard if not impossible to start cold, and when it would start, bike would die sooner and take longer to cool down enough to restart.

Finally, it would not start at all, no matter what you did.

Rewinding the stator fixed it.

BTW, my stator would measure within spec (the old '84 manual had resistance specifications), which made this a tough problem to diagnose.

FWIW, I did have my flywheel key shear on that bike too, but it would not run at all when that happened.

 

[sr5bidder]

good stuff Dave
did you ever check the resistance while hot?

 

[dirt bike dave]

You know, I don't think I ever did.

Can't remember for sure, but don't think I ever had a multi-meter with me when it died while hot.

By the time I was convinced it was the stator, I could not get the damn thing started to run long enough to even get hot. Stator still checked out fine cold, though.

Loved the '84 BTW. Bad forks like all other stock KDX's, lol. Weak brakes, too. And the stator problem sucked. Other than that, fine bike for its time and a real joy to ride in the woods ;)

 

[willub]

That's exactly what was happening when my friend had it Dave. Started and ran fine until it got hot and then it would die, then took a while to get started.

Got 160 psi today so the engine is fine. Took the magneto cover off and it was filled with water lol. Didn't realize you "need" a special tool to get the mag rotor off. So I cleaned it up as best I could and put it back together. Tried kick starting it and it wouldnt even try. It fired a few times when I rolled it down my driveway and then BAM, locked up completely. Took the cover back off and pieces of magnets were falling out and jamming against the case so it wouldn't turn over. found the problem!

So my questions are: What exactly do I need to replace to get it back in working order besides the stator? Where would I get the magnets? Cant really see whats in there since I don't wanna damage the rotor prying it off. What do you guys use to get the rotor off other than the tool? Thanks again

 

[sr5bidder]

your **** out of luck dude...see above post where I said about the magnets???

the only thing you can do now is buy an expensive stator kit that allows you to put a 95+ kdx rotor on it from frp racing.... the flywheels in good shape go for $175 + on ebay when a good one comes up..

in other words you had a good flywheel earlier today but now you dont...whatcha going to do??

 

[dirt bike dave]

Sucks about the magnets. A little chip or two is no big deal, but when big chunks start falling off that's going to be difficult if not impossible to repair.

An automobile steering wheel puller can be used to get the flywheel off, but be warned that after 25+ years that thing will be locked in place very tight.

Overnight soaking with liquid wrench or pb blaster will help, as will tapping the flywheel as you torque the puller down. But it's going to take some serious torque and when the flywheel pops off it will do so with a bang!

 

[sr5bidder]

yeah and dont have your hand on it...might sting a bit

 

[willub]

I'll try jb welding them together if I can find the pieces. If not I'll find another flywheel. One on ebay from a 91, looks exactly the same but will it work?

 

[willub]

Got the rotor off with a steering wheel puller. (thanks for that idea)

Only a few chunks have come off of the magnets and that is all that appears to be wrong. Hard to find the parts for cheap so I'm just planning on cleaning everything up and reusing everything since the stator checked out ok, although that doesn't mean much apparently haha.

 

[willub]

Ok I need a new stator. Still getting zero spark. What comes with these aftermarket stators I've been seeing? does it just come with one? also what year stators will work with the 85. someone has a parts motor for 40 bucks near me but he didn't list the year.

 

[reepicheep]

I got just the coils from Ricky Stator for my son's KX-60, and was very happy with them. They screwed onto the factory coil assembly frame.

For my KDX, I scared up a coil on ebay from somebody parting out the bike, that was the whole thing (frame and coils).

Not sure about your 85, but my 95 has two coils, one for lighting and one for ignition.

 

[willub]

Got the new stator ignition coils in and I'm still getting zero spark. Coil is reading 8.1k ohms for the secondary and .7ish ohms for the primary which is off by quite a bit. The new stator coils are way off too, just like the old ones. I'll look at the wiring but none were at zero or infinite when I tested them. Is there any way to test the cdi box? Says in the manual you need special electrical equipment. Any place I can get a new coil for cheap? If not I'm probably gonna get another bike

 

[reepicheep]

I think ignition coils are fairly universal... you could plug in just about any dirt bike coil and it would probably work. I had a generic aftermarket one from a friend (Emgo or something) and one off a KLR-250, and both looked like they would work.

The CDI box is pretty complicated. It senses temperature and some other stuff, and has an interesting analog computer to adjust timing. But I also think it is unusual for them to die.

These kinds of problems are hard to track down. You want to isolate each part and test it completely. But when that isn't conclusive, you are running in circles.

Start by testing the voltage (and current, if you know how to do that) output from your stator coil, and make sure juice is getting to the ignition coil.

 

[willub]

I will try that tomorrow. A lot easier with two people. I would be testing the blue and red/white wire to ground, correct?

 

[willub]

I tested red/white to ground and blue to ground from the stator. Both are producing 2-3 volts (hard to tell because the multimeter updates slow). I tested the wire from the cdi box going to the coil and it is sending the coil 12-25 volts (seems high to me). I'm assuming this means the coil is bad.

 

[GreenMachine1990]

i just had the same stator problem the surfaces that the magnets rotate around must be clear of rust and corrosion get some electrical contact cleaner on those grooved plates and scrub the hell out of em with a wire brush when they are shiny metal u will get spark also take all the chipped pieces out of there

 

[willub]

Ok I got a new coil and it is getting a tiny bit of spark but not nearly enough to do anything and barely shows on the multimeter. The stator coils are working, the coil is working and the wiring is fine. I'm guessing the cdi box is fried. Makes sense too since the ignition coils were underwater for however long.

There has to be a way of testing this thing. There is one on ebay right now but it's 100 bucks used. I'm not afraid to pull it apart to test it so if anyone knows anything let me know. thanks

 

[sr5bidder]

remove the kill switch and give it a try you may have a partial ground there

 

[willub]

tried that