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KX500 / KDX Flywheel Interchangability


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I have a dualsport '90 KX500 with a KDX200 lighting coil rewound by BD mounted on the stock KX stator plate.  It sorta works however the output is not nearly as good as a KDX200 using the same coil.  The coil I have is definitely good, I have two and they both demonstrate the same issue.  My suspicion is that the power loss is caused by a difference between the magnet structures of the KX and KDX flywheels.  The Kawasaki p/n's appear to be different.  So my question...

 

Can a KDX flywheel be installed on a KX500 crank end?  If so, what year?

Any other ideas regarding this topic are welcome too...

 

Merry Christmas

KX500.jpg

KX500_1.jpg

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Just an idea, have you tried checking how large the gap is between the FW and lighting coil? It should be as close as possible without physically touching it. If there is a sizeable gap you might try reworking the lighting coil mounts to reduce it. Plus, does the lighting coil sit completely within the FW? If not, shim it until it does. I know neither answers your original question, as I don't know, but I hope it might prove useful.

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SS190 - The lighting coil is definitely located in the flywheel properly but that is a good suggestion, thank you. 

 

If you're interested, my test setup is a 55w bulb attached directly to the 2 leads (floated ground) from the coil with no voltage regulator, just a meter.  On a KDX this coil brings a 55w bulb to full brightness (12ACV) at around mid throttle with plenty of RPM left to blow out the filament while the meter displays a linear voltage rise proportional to RPM.  On the KX5 the voltage reading is very erratic and inconsistent proportional to RPM, peaking at ~10ACV.  If the coil were located too far from the ID or out of the flywheel I would expect low voltage but not all the bouncing around which is what makes me think the magnets aren't playing nice (plus the coil would likely contact the center snout of the flywheel as there's not much room for misalignment.)

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***Update***

 

I managed to borrow a flywheel off a '90 KDX200 and was able to install it on the KX500 with no problem (same taper, same key position, fits inside the cover etc.)

 

I’m starting to think the erratic voltage readings I was seeing might be a function of my multimeter failing however it seems to measure current just fine.  That said, wow what a difference! The KDX flywheel significantly woke up the charging system.  The difference in magnet strength was noticeable just plunking it on the crank end. 

With the stock KX flywheel and 35w headlight, the battery has never been able to charge and would only see a positive flow of current from the rec/reg (<.5A) at an RPM I don’t ride nearly good enough to maintain.   With the KDX flywheel installed, the battery current would go positive just off idle, easily rising well over an amp by mid RPM.  Looks like problem solved.

Hopefully this helps someone in the future.

Edited by moleculo
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zz3gmc- Yes, the KDX coil matches up with the mounting bosses on the KX stator plate however they need to be drilled and tapped for the mounting screws.  The bosses are dimpled where the holes should be located.  As I recall the correct screw size is m4 but verify first, I could be wrong.  I've rewound quite a few different stators and the KDX is among the easiest. 

 

On a separate note, it appears you've been on TT for about 10yrs same as me.  I miss that time when TT was a bit more raw, with characters like TwoBlackBelts posting in the off-topic forum.

Edited by moleculo
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I managed to get the KDX fw off of the donor engine tonight but the KDX lighting coil was damaged badly. It looked like it had melted! My 500 has what i believe to be a 65w Moose Racing lighting coil. Like yours, at low revs the lights would go so dim that i couldnt see unless I kept on revving it. I may instal just the fw with my coil and see how it goes. I believe a 91-94 KDX250 fw may work also. Different p# from the 200 but the crank taper is the same.

 

Ive been on here for about 10 years but I dont remember TwoBlackBelts. Ive been mostly in the bike specific forums.

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  • 7 months later...
  • 3 years later...
On 12/28/2014 at 5:02 PM, moleculo said:

***Update***

 

I managed to borrow a flywheel off a '90 KDX200 and was able to install it on the KX500 with no problem (same taper, same key position, fits inside the cover etc.)

 

I’m starting to think the erratic voltage readings I was seeing might be a function of my multimeter failing however it seems to measure current just fine.  That said, wow what a difference! The KDX flywheel significantly woke up the charging system.  The difference in magnet strength was noticeable just plunking it on the crank end. 

With the stock KX flywheel and 35w headlight, the battery has never been able to charge and would only see a positive flow of current from the rec/reg (<.5A) at an RPM I don’t ride nearly good enough to maintain.   With the KDX flywheel installed, the battery current would go positive just off idle, easily rising well over an amp by mid RPM.  Looks like problem solved.

Hopefully this helps someone in the future.

Ricky Stator has their #RSL34 that is a 50W lighting coil for the KX500, they also have the #RSL33 that is a 85W lighting Coil for the KDX200.  I was told by Ricky Stator that their #RSL33 is taller and won't fit under the KX500 flywheel.  So if you can fit the KDX200 flywheel on the KX500, then adding the #RSL33 should be beneficial and give you more power than the existing coil.  It is possible that the 65W Moose stator with the KDX200 flywheel may even do better than the #RSL33 with the KDX200 flywheel, but with the #RSL33 and KDX200 flywheel you should at least know that it will do 85W.

 

On a side note, does anyone have any experience with the Powerdynamo charging system?  It is supposed to do 100W and replace the ignition system, at a much higher cost.

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