I'm working on a valve adjustment for a 1994 Suzuki Katana 600. I'm at the point where the signal generator cover is off and I'm ready to rotate the engine and make my measurements. However, the manual simply says to rotate the crank in the direction of normal operation. I'm looking at the signal generator and I don't see any indication on which direction that might be. Looking at the valves and camshafts themselves, one side looks to be a mirror image of the other, nothing obvious indicating direction there either. It's clear from the pipes though that the exhaust side is to the front of the bike and intake side is to the rear.

In the specific case, standing next to the bike (on the right hand side), facing the signal generator, which way to I turn? Clockwise or counter clockwise?

In the general case, what are the indicators to look for to know what the direction of normal operation might be?

  • You should also tell the correct direction by the order in which intake and exhaust valves are actuated by your cam shaft. – towe Oct 19 at 5:53

The usual direction of rotation for a motorcycle engine with chain or belt drive, is the same as the driven wheel.

This allows a "straight-through" ratio where the gearbox does not use the lay shaft. For other ratios, the direction is reversed onto the lay shaft and then reversed again onto the output shaft.

The position of the inlet and outlet ports is not affected by this, since the pistons go up and down regardless of the direction of rotation of the crankshaft. The exhaust ports are at the front, because it is easy to route the pipes from there, and because the fuel system is protected by being behind the engine.

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