I recently bought a 1990 blaster without an air filer or air box. A guy near me has an air-box off of a 2006 blaster. I was wondering if it would fit mine or it would be better to go with a clamp on air filter directly into the carb?
Depends on where you ride and what you ride through. Just the clamp on filter is fine for pavement, gravel, grass, etc.
Mud, water, anything that may hinder the open filter. You should at least run the box with no lid.
