Before you listen to Hawk here, I'd read the rule book. I've never routed my coolant overflow into my airbox. Maybe I've been doing things wrong all these years.http://www.ccsracing.us/forms/2009/rules/2009%20asra-ccs%20rulebook.pdf
"5.2.15 On 4 stroke machines, crankcase ventilation must be routed into a
heat resistant catch can of at least 350cc capacity or the air box.
A. If ventilation is routed into the air box, any drains from the air box
must be sealed.
B. If ventilation is routed to a catch can, the overflow tube from the
catch can must be routed into the intake area of the carburetors so
that any overflow from the catch can will be drawn into the engine.
C. Radiator overflow and battery vent tubes may be routed into a
separate catch can that need not be vented into the intake area.
D. Final approval of the catch can system rests with the Tech Inspector."
Nope, didn't think so.
The overflow from the coolant reservoir must still be routed to the airbox and the airbox must have any holes in the bottom sealed.