Tech Corner

CDI, Stator, and Coil – Who Does What?

In simple terms:

• Stator makes AC power and a trigger signal as the flywheel spins.
• CDI stores that energy and decides when to fire based on RPM and its timing curve.
• Ignition coil steps the voltage up so the plug can jump the gap under pressure.

When any one of those pieces gets weak, hot, or unstable, you feel it as misfire, flat spots, or a bike that feels fine in the garage and awful under load.

Simple View of Timing

• More advance = spark happens earlier = more mid/top, more heat, more risk.
• Less advance = spark happens later = softer hit, safer, but leaves power on the table.

The “right” timing is a mix of compression, fuel, pipe, porting, and how you ride. That’s why the timing kits are based on ranges (like +3°–+7°) instead of one magic number.

Using the Timing Kits

The Blaster and Tri-Moto timing kits use jigs that line up to the stator so you can mark precise positions and slot them. Once that’s done, you can move the stator to known advance ranges instead of guessing.

• Start at the mildest recommended setting for your build.
• Verify fuel and jetting are good before pushing timing higher.
• Listen for knock under load and check plug color regularly when changing timing.

Each product page will eventually have a PDF with more specific suggestions for that engine and kit.

Signs Your Stator is Letting You Down

• Bike runs fine cold but breaks up when fully hot.
• Random cut-outs over bumps or at a certain RPM.
• Weak or inconsistent spark when checked properly.

Why Rewind?

Old insulation, heat cycles, and vibration kill coils slowly. A rewind with high-temp magnet wire and proper insulation gives the CDI something solid to work with.

If you’re chasing down weird electrical gremlins on a 30+ year-old 2-stroke, a proper stator and a known-good CDI eliminate a huge chunk of the guesswork.

For details on sending in a stator, see the Stator Rewind Service page.