santidreamer

Member
May 7, 2008
8
0
I bought an old SR model KDX which has never run right.

The engine has been re-built and the Carb. replaced but it still runs like a dog.

It is OK at low rpm and missing badly at full throttle. There is a lot of unburnt oil and fuel in the exhaust.

I have tried re-jetting and plug chop, the spark plug color is fine.

I believe the CDI may be at fault, but cannot find a replacement.

Worryingly the CDI is different from that shown on any diagrams I can find (KDX 200 89/94 manual or KDX 200 F1).

The CDI wires are:

Red + white (to stator coil)
Black

Black + yellow (to Ground)

Blue (to ignition coil and grounded by kill switch)

black + white


I have no idea what to do next.

Thanks
 

EYY

Member
May 22, 2010
159
1
1.If you haven't already, make sure you change the spark plug(you'd be surprised how often it's ovelooked)
2.disconnect, one by one all of the connections on the bike. If there happens to be a short somewhere around the circuit, this can draw power from the ignition and produce too weak a spark. (happened to me once and turned out to be a dodgey brake light switch :S)
3. Check your ignition timing (set by rotating the stator plate)
4. swap cdi's. I've seen numerous used cdi's for sale online for low prices (under $20).

Hope you're able to get it running properly soon!
Good luck, Craig
 

reepicheep

Member
Apr 3, 2009
670
2
Any real world data on people that really did have one fail? They are easy to blame (I have done it) when you are hunting ghosts because they are voodoo anyway... but every time I wanted to blame mine I eventually tracked it down to something else.

So anyone who really had one fail want to chime in? A "ran awful, swapped CDI, ran great" story?

It was probably the *only* thing on my 95 basket case that wasn't broken when I got it... so it must be pretty darn tough! ;)
 

santidreamer

Member
May 7, 2008
8
0
Firstly thank you, I was feeling more than a little lost.

I live in Thailand spares parts and qualified mechanics are rare.

I have elimated the following.

1. spark plug (new)
2. ignition coil (swapped)
3. stator coils (resistance close to spec) 30V at tick over.

I have yet to check for ground short circuit faults, (very good idea.)

I do not have access to spare CDI but may have found one on ebay.

In the workshop manual it shows a special tool to check spark strength the spark should jump a 6mm gap.

My local mechanic removed the spark plug cap from the high volatage wire, then held the high voltage wire a few mm from frame and kicked it over.

His hair stayed flat ot his head and the spark jumped the gap.
 

EYY

Member
May 22, 2010
159
1
During the rebuild was the stator plate removed? If so, it seems a common mistake for people not to mark where the stator it was sitting before the rebuild. It sounds as though the timing may be too far retarded. You will need to remove the flywheel to reposition the stator plate if you feel this may be the problem. Once you have the timing set on a bike with electronic ignition, it will never need to be adjusted again.
 

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