What's the best air filter that fits the stock airbox?
I agree the donaldson is not working in the silt beds. I see a fine layer of dust in the intake. I have noticed that the donaldson filters seem to vary in overall length by as much as 1/4". They have been really good about replacing them. I have the BRP Foam sitting on my bench and that will go on next.I live in some pretty dusty areas here in AZ. You may have more people from AZ tell you how bad it can be following people. I had been running the stock paper element but was finding a small amount of fine dust getting through. I've been an off road dirt bike racer for 30+ years and found that the only "type" of filter that keeps pretty much everything out are foam air filters. Saying that..... I installed a Twin Air foam filter and have not had any fine dust get through. It is a double filter which is nice but may restrict some of the air flow. So I took off the outside layer and installed a S&B particle separator. The last race I was in was so dusty I could barely see the car in front of me only 1 car length ahead. Took the cleaner off after the race to see just want might have gotten through.... Nada, clean as if I had just clean it. Just my 2 cents.....
It might...... However, I have a fresh air system for my helmet that came with one of those pre-filters. It also has one of the blue filers. When it is really dusty (as mentioned earlier, where you can't see right in front of you), I can still smell dust. On these races now I bought a universal Uni foam filter and now use that for my fresh air system. For what ever reason, foam just seem to catch more dost. To add..... the S&B partial separator is doing a great job also....How about a stock filter with pre-filter. Would that help keep out the fine dust?