Motorcycle Repair: XR600 timing, compression stroke, stroke cycle

Question
Hi I have rebuilt my XR600 and I'm setting the timing, I have put the flywheel to match up the T mark and the 2 marks on the cam sprocket are lined up with the surface of the head. My question is how do I know if I am not 180 degress off?

Answer
Hi Randy,

The piston needs set at TDC on Compression Stroke for cam reomval. Setting the piston 180 degrees away from TDC on compression stroke is easily and often done.

TDC is TDC whenever piston is at maximum lift when cams are not installed. Camshafts/valve lift determine which stroke cycle the piston is on.

Following the installation procedure and alligning timing marks will get cams on-time. Otherwise, the cam is upside down. I doubt it will install that way.
: )


Respectfully,
Mark Shively