Crankcase breather connects to...?

Patton wrote: "Where stock S-tube or L-tube connection to the air box risks fuel contamination into the crank case (due to lack of carb overflow circuits or non-functioning carb overflow circuits due to blockage or whatever reason), a large i.d. tube may be used to route the venting to underneath or behind the bike."

I can’t speak to the KZ900/1000 configurations, but the stock breather tube on the KZ650/750 does not create a risk of fuel going into the crankcase. The stock "L" shaped tube enters the airbox about 1 ¾” above the level of the drain hole. So unless gas or water was really pouring into the airbox at a super high rate of flow (more than the petcock can deliver) it would run out the bottom of the airbox through the drain before getting close to the breather tube level. The first picture shows the inside of the KZ650 airbox. Notice toward the top of the picture the hole that enters from the breather tube nipple and notice the drain hole near the bottom of the picture. The breather nipple is much higher in the box than the drain (which is at the very bottom). The second picture shows the bottom of the air filter holder. Notice the three scalloped holes. When the air filter holder is inserted in the airbox, these three holes let gas or water pass by the bottom of the holder so it can flow to the drain. Ed

Just put mine back on today, Airbox. Though you can just let it run out, or put a filter on as suggested above.

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