If there is a question about that filter,
fix it at any expense. Ensure nothing gets through to the engine except pure, cool air.
Here's another interesting thought about volume..and yes, maybe a rambling but I need to unload it so I can move on
:
With no intake or exhaust restrictions, An 800 CC engine running at..well lets say for ease of calculations, 8000 rpm will flow 6,400,000.00 ccs of air every minute. That's 106,666.66 ccs every second. That's minimum so lets add 10% to give us some room for a dirty filter..10,666.66. So in theory, we need a filter and intake system that can flow 117,333.32 ccs of air every second. Sounds like a lot of air....and it is. Now we need specs on filters and their surface flow rates per inch/centimeter and some airbox specs to get it right. Yes, this is overkill as there is much restriction in exhaust and intake and the FI system is tuned for this as part of the EPA requirements but..wouldn't it be nice to know and have exactly what it needed..to have it right for this engine? Intake restriction, in order to remain a constant must be part of the airbox or piping design and never the filter as it's flow rate changes with every mile of dusty roads. So the filter must be sized large enough not to effect flow rate for a reasonable amount of time. And from my observations, most stock filters of 800cc & larger engines are larger..or have more surface area then the stock CFMoto 800 filter even with it's pleats. This has always concerned me as when you force higher volumes of air through smaller surface areas, you loose filtration as things are just forced through where the slower the flow of air per surface square inch better entrapment happens. It's this thought that makes me think this is why partials get through the stock CFMoto paper filter. It just does not have enough surface area for the volume it's pulling through. The UniFilter or Twinair filters filter and capture better by design of their filter media, but actually have less surface area then the stock filter as they have no pleating. Have you seen the paper filter they put in a Polaris 800 or 900? Much larger then any CFMoto.
OK, rambling over...probably over thinking this anyway but food for thought for those re-designing the air intake system on these.
One more thought and then I'll be quiet.
On this system we now have the crankcase vent on the filtered air side where most other manufacturers have them..but, if the filter is restrictive, this means increased vacuum between the filter and throttle body which also means increased vacuum on the crankcase. I have seen where increased vacuum on a crankcase pulls additional blow-by past the rings causing oil on the cylinders to migrate away from the two surfaces...causing accelerated wear. It also can so the same on main seals if it's high enough. You may want to test it with a low-level vacuum or water gauge to ensure there is no readable vacuum on the crankcase at high RPM. Remember originally they had it tapped to the outside of the filtered air area in the box where it would never get any real vacuum, just pulsed and exhausted in the box.