by: Eskort


Why? - Provides a minor improvement in fuel economy & torque by adding 3 degrees of ignition advance at all rpm.

Items required:


  1. Remove the pickup coil sidecover. There are eight socket bolts requiring a 5 mm allen hex driver. Note that the lower left bolt has a retainer under it for the pickup coil wiring.

  2. Carefully remove the sidecover. There is a pin (about 6 mm diameter x 25 mm) that retains the cam chain guide on the left hand side of the opening. If it comes out with the cover, realign the guide and replace the pin in the boss.

  3. Remove the bolt retaining the timing rotor by rotating it counterclockwise. This can be a task. The manual says to retain the flywheel located on the other side of the crankshaft with a special tool. I put the bike in top gear, and had someone sit on it and hold the rear brake while I gently applied torque to minimize peak loads through the gear box.

  4. Prior to removing the rotor, note the printing embossed on the outside of the rotor. You will need to reinstall it this way. Also, take a Sharpie or a scribe and mark the horizontal centerline of the crankshaft pin in the slot of the rotor. This will be the key measuring point.

  5. Flip the rotor over and reinstall on the crank end. Again mark the horizontal centerline of the locating pin.

  6. Remove rotor. On the face of the rotor, scribe a vertical line at 0.6 mm to the left edge of the slot intersecting the horizontal centerline, this is a reference line. Also, put a vertical line 0.6 mm on the back of the rotor to the right of the slot, a second reference line.

  7. Measure the width of the slot at the horizontal centerline. It should be about 4 mm. Add 0.6 mm to this dimension. This measurement will be used to ensure the proper dimension is achieved.

  8. Using a 3-4 mm diameter round file, begin filing on the left of the slot with the file centered on the horizontal centerline of the locating pin. Flip the rotor over and file from the back to keep the side of the slot as straight as possible. Measure often to see where you are in approaching the 4.6+ mm dimension. When you are close, use the half round file to widen the opening on the left of the slot. (Note: I actually did not remove material all the way down to the base of the slot as removing material in the location of the pin is all that is required.)

  9. When youíve reached the 4.6+ mm dimension, ensure that the new left side is flat from top (outside) surface to bottom (inside) of the rotor. You should be able to install it on the end of the crank and rotate it back and forth the 3 degrees. While holding the rotor clockwise, reinstall the washer and bolt retaining the rotor and torque to 43 lb-ft (60 Nm).

  10. Reinstall the sidecover with a new gasket using Yamabond in the area of the rubber grommet. Snug, then torque socket screws in a crisscross fashion to 8.7 lb-ft (12 Nm). Note that the lower left bolt has a retainer under it for the pickup coil wiring.

  11. Confirm timing change using the degree wheel (below) and a timing light (see Yamaha manual). Please be sure to read the warning below. Whether the slot is cut so that you have 2.5 degrees or 3.5 degrees won't make much difference. But I would discourage any large change from the 0.6 mm calculated. Do not attempt this without a micrometer.

The Math:

Warning: Advancing the engine timing too far, or without proper carburetion changes (like a jet kit), could result in spark knock and potential engine damage. The information presented reflects solely my personal experience with my motorcycle and is presented for entertainment purposes only. No information presented here is to be relied upon for issues of rider safety nor to replace the services of a qualified service technician. Any attempts to follow or duplicate are done so completely at your own risk. By reading this, you agree to assume complete responsibility for any and all actual or consequential damages that may arise from any information presented.