TRIAL BY AIRBOX: MR. KNOW-IT-ALL

BOXING WITH AIR
Dear Mr. Know-It-All,
Can I delete the airbox on my old Aprilia (Rotax 277cc) two-stroke (trials bike) and just install a clamp-on K&N air filter to the back end of the carb? Some people say the box is there and can’t just be removed. I understand that I may have to richen the jetting to compensate for the added air volume. I’m not concerned about water getting on the filter. I’ll just ride it in fair weather.
I know, I should have known, but too many people keep telling me it’ll never run right.  Please settle this mix-up for me.
Marion Cassidy
via [email protected]

I’m curious, Marion, what are you trying to accomplish? Is it worth the headache of rejetting and having debris enter the motor? I’m not a huge fan of the tiny K&N-style filters on anything dirt-related, even with an applied oil. I don’t believe they are as efficient as a quality oiled foam filter at protecting your engine from ingesting fine dust. If you choose to run the K&N sans airbox, I would put a foam sock around it. Back in the day, we did this on our Can-Am machines, and it worked well. The bottom line is that more airflow is all well and good, but I’m all about added reliability.