Hello,

Picked up a Baja Wilderness 250, Bear Tracker clone.
The wiring was completely gutted, so re-installing basic ignition wiring, with no additional lights/etc.

Ordered a regular wiring combo with 6 pin CDI, wiring everything up and got spark/started.
However, engine backfires really badly.

Confirmed timing is fine, brand new carb, spark plug, still the same.

Now the confusing part is that original CDI was a 7 wire slot, where Pickup Coil has 2 wires coming out of it vs 1 wire on regular chinese quads.
Pickup coil has Black and Blue wires coming out of it.

Initially i thought Black wire must be additional ground just for the Pickup Coil ( although confused as to why, if Stator itself also has a ground wire? ) and Blue is obviously pulse wiring.
Now i'm not so entirely sure and been reading about replacement Pickup Coils on Bear Tracker having wires crossed, causing backfire.
So the question is then, what the hell does the Black wire do if Blue is a pickup?! Is it simply ground and can be grounded to the chassis?
In original diagram, both Blue and Black went into CDI, but the diagrams don't explain what the CDI pins were for, since some CDIs have 2+ ground pins.

Does anyone know what exactly are these Pickup Coil wires for ( Black and Blue )?

 

Some "pickup" coils are earthed, many have both wires going to the CDI. On the ones with two wires, if you get them the wrong way round it alters the ignition timing by a few degrees. I can't see any reason why you can't earth one wire to make it work on a CDI made for an earthed pickup. However you must chose the right wire to earth, or you will get the timing problem. Also advance retard differs on CDIs made for different engines, so timing may never be spot on if using a CDI made for something else.

 

Well, swapped wires, grounded BLUE to chassis and BLACK to pulse on CDI, running smooth now, what a weird setup

 

Not weird at all, the big Japanese makers all use two wire pickup coils. Some Chinese bikes earth one phase of the stator so they only need two wires to regulator but again the big makers seem to use three wire, non earthed stators.