Off hand I can't quite recall the 173 but Honda in gerneral is pretty much the same. Have the cable retaining clamp on the engine just loose enough that the cable can freely be moved back and forth. At the operators control lever move lever to the full speed detent, past would go into choke.

Then go back down to the engine and slide the cable towards full throttle until the mechanism contacts the choke lever, make it a snug fit against choke lever. Tighten the cable clamp and do so with a little extra grunt. Make sure you use a good fitting phillips screw driver.

Then check operation, make sure when you move lever past full speed detent that choke is fully closed. Sometimes you will need to make a minor cable adjustment to get full choke but if you do go back and make sure the choke opens all the way when lever is returned to full speed detent.

Bob