MBK CDI

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CDI Diagram.jpg


To wire up the stock mbk cdi stator to the unlimited Yamaha box, follow this:

The Yamaha Unlimited box can be found on ebay [1]. In case the link expires, the retailer is "Taipei Scooter Assassins", and searcing "yamaha unrestricted" in ebay should yield results. a

The Stator Black wire is the frame ground, wire it to somewhere on the frame itself
The stator yellow wire is the 12v lighting & accessories circuit, wire that to your headlight and taillight
The stator red wire is for the ignition timing which goes to the Yamaha CDI’s white and red wire
The CDI box’s orange wire goes to the high tension coil, thats the plug facing down to the ground on the white HT box
The CDI box’s black wire goes to ground out both the HT coil and the motor, so ground that out to the motor either by having the wire squished under one of the crank case bolts or to the long bolt that the motor pivots on.
The Stator’s green wire goes to the CDI box’s black and red wire, I have no idea what it does but it completes some sort of a circuit and is essential for it to run.
The CDI box’s black and white wire, when grounded out to the frame, will be your kill switch. Wire it to one side of a DC toggle switch and have the other side be wired to your frame.

Timing

Both the stator plate and flywheel have a timing mark. When these are lined up, the unit fires. Set this to occur at the same time that the points would normally open. see Guide to Motobecane spark and timing.

Usage Notes

  • The CDI box that comes with this kit (from Treats or 77) is restricted. I have seen this CDI on stock mobies running as fast as ~35 MPH without restriction kicking in. This would be circa 5k-6k RPM with stock variated gearing (11:54)
  • For anything more than stock, an unrestricted CDI box should be used. However, this may allow the engine to spin up to RPMs past the design specifications of the stator plate, therefore overheating and frying the coils. This is a habitual occurence with this CDI unit.
  • For reference, the restistance of a functioning primary (ignition) coil is circa 350 ohms. The resistance of a fried coil is circa 150.

Installation Notes

  • Your Novi nut will not fit down into the recess on the flywheel. Use a different nut or grind yours down.
  • Use a voltage regulator. This unit puts out a lot of power and will blow your lights.
  • This unit uses a puller with a 19mm x 1mm thread size/pitch.
  • Stator plate is smaller in diameter than the points stator plate. Your flywheel cover will not fit.
  • Brake light system will need to be modified.