Air pre-filter - seems good.

[bikerpet]

A while back I decided to try fitting a pre-filter to my bike.

I had a piece of 25mm thick coarse reticulated foam (ebay fish tank filter foam) that I'd tried to use as a baffle as described somewhere for SSDT prep - that never really seemed to do much so I thought I'd try a different approach for my drier conditions.

I cut the foam down to 6-8mm thick and cut a few pieces shaped to fit under the filter clamp. Oiled and fitted.

Works a treat! I check it fairly frequently and swap out when it gets grubby. The main filter stays far cleaner and swapping, cleaning and oiling the pre-filters is much quicker and easier than the main filters, and the piece of foam that cost just a few dollars will make a bunch of pre-filters so I can keep several prepped and ready. I can't feel any difference in the way the bike runs or rides. The one below was let go longer than I usually leave them.