Feedbackloop

FeedbackLoop

Q I found your response to Michael Fricke's letter in the October issue ("The unfiltered truth”) accurate and informative as always, if somewhat incomplete. While I certainly agree that running without an air filter is a bad idea for all the reasons you stated, you neglected to mention an equally important function of the filter that is not often discussed. Filtering intake air is indeed this component’s primary job, but it also does double duty as a flame suppressor. This is especially true on carbureted engines but important with EFI, as well.

Should the engine ever backfire through the intake, the resulting “blowtorch” effect occurs directly below the fuel tank. Without the air filter in place to arrest the flame (or worse, the series of flames), the obvious scenario can easily occur.

Stock motorcycle air filters these days are amazingly efficient as is, and if that’s not good enough, companies like K&N have

no doubt done their homework, as well. The bottom line is that there is no compelling reason to run a street motorcycle without an air filter. You may or may not notice a slight performance advantage without one, but you will definitely notice a significant decrease in power when you are on fire! Just my two cents. Jeff Hamilton Vallejo, California

A You're absolutely right: I did not consider that possible consequence. I guess I never thought about it because the likelihood of a backfire on a properly tuned engine is remote; and even if one did occur, it would not necessarily ignite anything around the fuel tank-unless, of course, a small amount of gasoline was seeping past the petcock gasket or dripping from an overflow tube. But it never hurts to avoid such possibilities in the first place. So, thank you very much for the heads-up.