A Dirt Bike magazine article from within the last year or so explained in all their testing, removing the screen provided no observable benefit on the dyno. But riders noticed it did result in improved throttle response. Maybe I'll break down and remove it some time.

 

Just an observation to add, though not directly motorcycle/engine related.

My house does not have central air conditioning and since I hate the ugly look of window mounted AC units we have a couple of "portable" AC units that (for those not familiar) are basically a self contained window unit but with a hose that connects to the outside to vent the hot air and another hose that drains the water produced during the cooling process (mine goes into 5 gallon buckets).

Anyway not to bore anyone with the details of my home cooling solution I noticed when we first installed the units a couple of years ago that 2 of them seemed to not cool the room very well and got hotter than the other 2 units. Before taking them back to the store I figured it would be a good idea to switch all of them around and sure enough the two that were working fine started acting the same way when installed in those rooms/vented to those windows.

Windows that I had the previous spring replaced the screens with fine "no see-um" window mesh. the super fine mesh screen was preventing the AC exhaust from venting out of the window as fast as it should, something I confirmed just by feeling the amount of exhaust standing outside of the window. the units that were working properly were installed in windows that had the old course mesh screens. Taking the screens out entirely seemed to have helped as well, but not to a large degree that I can quantify due to variances in daily temps/sunlight and other factors that contribute to how hot your house gets day by day.

at any rate, I removed the screen from my KLX after my AC revelation.

YMMV

 

My jetting felt soft after screen delete. On the KLX it makes a difference, I went up one on the main and feel I could benefit from a bigger pilot. True moto bikes have way better airbox setup than our bikes. I too was worried about burning down on the trail, but run a K&N that has a screen. Might be a false sense of security, but I have never had the bike back fire through the carb. Fingers crossed..

 

I guess I need to explain my self a little better. The backfire screen is in the way. A engine is just a air pump, if the air going in or out is hindered performance will suffer. Also the seat on my KTM is hard.

 

I noticed a difference removing it on the klx, but not where you'd think (top end), but noticed a slight better pick up right off the bottom. This could be a result of more air, or change in fuel mix, or the effect on the carb slide movement, who knows.

Some of the screens the magazines may have tested were full size filter cage screen that sits right against the filter. The klx screen is smaller smack in the middle of the intake tract.

If you pull the screen on any bike, make dang sure overnight all the filter oil solvent is evap'd before starting the bike. I've posted pics here of my own filters singed with flame and I'm pretty careful about it.

 

Can you point us to those pics?