Stator coil

Joined
Dec 6, 2002
Messages
105
Likes
0
#1
I lost 3 stator coils the last two months.
The last one lasted 3 rides & burned.
The bike runs well & suddenly cuts out.
Will it be the high tension coil or the igniter that cause the stator coil to burn?

Any one with similar problems in the past?

I am losing face with the fellow riders on the reliability of the KDX...
 

tedkxkdx

Lifetime Sponsor
Joined
Feb 6, 2003
Messages
393
Likes
0
#2
Are you buying brand new or getting rewound. I had a rewind done on my oem coil and it did not last but 6-8 months. I opted for Electrex since they were cheap in England. Also my ignition coil had one of the circuits out of range of resistance.
Maybe you are getting condensation or something since you lost one so quick. It does not take much to short them out. The fine wire is suppose to be covered with a very fine epoxy-like substance so the wires don't contact each other.
I don't think that any other system would be causing your stator to go out, but not 100%.
 
Joined
Dec 6, 2002
Messages
105
Likes
0
#3
The first two were rewinds. The last one a original.
Thats what I dont understand. If there is a short in the system there would be no spark at all. It runs fine for days & then suddenly burns the stator coil.
It seems like the igniter ( CDI ) let the right amount of current to the HV coil, but also dissipates energy somehow that damage the stator coil.
I dunno....
 
Joined
Dec 6, 2002
Messages
105
Likes
0
#4
The first two were rewinds. The last one a original.
Thats what I dont understand. If there is a short in the system there would be no spark at all. It runs fine for days & then suddenly burns the stator coil.
It seems like the igniter ( CDI ) let the right amount of current to the ignition coil, but also dissipates energy somehow that damage the stator coil.
I dunno....
 

tedkxkdx

Lifetime Sponsor
Joined
Feb 6, 2003
Messages
393
Likes
0
#6
Check the entire wire lengths for rubbing that takes away the outer plastic of the wire. When I replaced my unit I had many places that were rubbed, none were all the way through though. Maybe some of your wires are corroded inside too.
 
Joined
Feb 18, 2004
Messages
5
Likes
0
#7
stator leaks?

The crank shaft that the magneto attaches to has a seal that sometimes leak. Is there any signs of oil in the case, if so this could be shorting your stator. I had this problem and went through 2 stators before I noticed a small film of oil slung inside the casing. Replaced the seal, problem solved.
 

jaguar

Subscriber
Joined
Jul 29, 2000
Messages
1,450
Likes
76
Location
South America
#8
If the capacitor starts leaking current to the ignition coil when the capacitor gets hot, that coould draw too much current from the stator coil and burn it out. Instead of replacing the CDI, you can carefully dig out the silicon/stone combo after cutting off the CDI box (which you'll have to replace). Be careful because the parts board inside the CDI sits really close to the top of the CDI box. Also the 16 ohm resistor (banded colors: brown, blue, black) would draw too much current from the stator coil if it has a lower value due to getting too hot. Replacement parts from www.mouser.com :
#23MA515 $1.27 (1.5uf/250v capacitor)
#660-CF1/2L160J $.05 (16 ohm, 1/2W resistor)
#625-1N4936 $.05 (1A/400v diode)
#80-T350C475K025 $.57 (4.7uf capacitor in case you damage it)
#334-NTC152 $.66 (1.5K thermistor in case you damage it)
#546-1551GBK $1.03 (plastic box 2” x 1.4” x .7”)
 
Joined
Feb 27, 2004
Messages
37
Likes
0
#9
This seems to be a common problem with the kdx range of bikes. The cable going into the side cover of the motor goes through a rubber grommet, the fit between grommet and cable is poor and breaks-down with age. If you wash your bike on a regular basis water finds its way into the cover through the grommet and causes a short. This is difficult to fault find because the water tends to evaporate (if you look carefully you might see some rust on threads of shaft or nut). The best solution to this is to seal the gap between grommet and cable with some black automotive silicon sealer. Hope this helps.