Where the ^%$#@! is TDC?

Applies to all Suzuki GS models.


Mad props to Jon Radermacher (jonr) for the close-up photo of his hot naked GS1100G.

The Question

Setting the #1 (and #4) piston at top dead center is an important step in any project that involves disturbing the camshafts or cam chain.

But which of the many marks is TDC?

Later Electronic Ignition Models (electronic advance)

TDC on a GSTDC for cylinders #1 and #4 is the hash mark between the "T" and the "F". Jon is actually just past TDC in this photo -- he needs to rotate the crank clockwise almost a full turn until the hash mark lines up with the #1/4 pickup.

The ignition pickup for cylinders #1 and #4 is on the left, and the pickup for #2 and #3 is on the right. If you have a 2 cylinder bike, the left pickup fires #1 and the right pickup fires #2. Just pretend you never saw #3 and #4.

The #1 cylinder is on your left as you sit on a bike. In case you were wondering.


Early Electronic Ignition (mechanical advance)
Points Ignition (very similar)

Early GS TDCIf the scene under your ignition cover looks like this, finding TDC is a little bit easier. There's a little round window in the ignition plate, and you align the "T" mark with the line in the window. E-Z.

Again, the pickup or points on the left handle #1 and #4, and the apparatus on the right handles #2 and #3.

On bikes with points, it's harder to see the window because you have points instead of ignition pickups, but the markings are the same.

Points are so... 1979. You really ought to call up the nice folks at Dynatek. They're doing wonderful things with them there newfangled electronical gizmos these days.