on the gx31 if the timing is off it will be way off, 24 crankshaft degrees per tooth</p>

all values @ .004" lash and crankshaft degrees</p>

stock gx31 cam .105" both approx.</p>

Intake open 25 btdc close 120 btdc</p>

Exhaust open 118 atdc close 10 atdc</p>

actual timing may vary due to lash settings ,wear on lobeand followers and axle hole.</p>

Because it is a single lobe design you only need to check intake closing point to determine if the timing is correct

btw the spring in the pump chamber does notmake it a four stroke carb, honda used 6 different wy models on the gx31and only half had springs.WOT stumble and acceleration issues <u>may </u>be addressed by cutting one coil at a time off metering lever spring nad using fresh diaphragms, if they are more than a year old they need to be replaced, most of the pumping issues with the honda is due to stiff diaphragms.</p>