What is your prefered air filter?

Curiousity kills the cat, check poll. 

Hiflo

Another HiFlo vote. 

Steel mesh screen, rusty and degraded from mouse piss, barely holding back stained Kleenex, insulation and kibble, with a top, mid-range friendly, layer of baby mouse carcasses. 

No air box lid for peak horse power.

K&N
Because its name sounds EPIC 😎

😁

K&N

Sprint

BMC 

Butt dyno can't tell any difference, defo runs better than any💩 paper throw away filter imho.👍

Piper cross 

I no longer own a VFR, but when I did I used a K&N filter for the last 8-10 years of my ownership of it.

My bike had the smaller K&N when I bought it. I swapped to pipercross for a while, but then I found the big K&N so I bought that. The difference in the size of the filtration area is very big. The most important difference is that the smaller filter partially obstructs velocity stacks with the rubber part, which is very stupid.

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Then I tested the big K&N vs Pipercross by accelerating in 3rd gear on a flat piece of road, back and forth four times and then averaging the runs. I used a phone camera to video the tachometer and using video editing software I timed the each 1000 RPM segment, from 5000 to 11000 RPM. The K&N was slightly, but consistently faster, with a difference that equates around 1hp over the whole rev range.

The test could be improved by running in 4th gear, so the bike would accelerate slower and the differences would be more pronounced compared to the measurement resolution, but the runway would need to be much, much bigger as the 4th gear can take you up to 200 km/h.

Interesting.  Do you know part number of the one with larger surface area?

The one I bought had HA8098 written on the bag. Problem is, online retailers put generic pictures of either type with the same part number so I couldn't know which one I'll actually get. I waited for a new, sealed one to pop up on ebay with actual pictures of the product so I knew what I was going to get.

So... A confession, I really wanted to see what is most popular/recommended and get ideas since I overthink near everything on a bike teardown/refresh.... 

Exhibit 1. I use a BMC for about 15ish years, liked it, but recent teardown/removal it split... hmm, maybe pass this time? 

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The "rim"

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I thought a pipercross might be interesting to try, bought one.... 

Bottom view

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Top

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The thing is it doesnt fit all that well, could be made to fit with some dremel work in the front radiuses.... 

Fooey! Install rating 5 out of 10.. (Maybe I was doing it wrong, but my patience is gone)

Somebody mentioned High Flow, bought one of those... It's closest to OEM.

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It turned out to be a little bit warped front to back, but it will go together fine with a bit of finagling. 

Its ok, but still kinda fooey.....Install rating 8 out of 10. 

What did I do? Spin cycle brain me, buys another BMC!

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This one fits fairly well, but not as good as the 15 year old piece....

Original fit rating on 15 year old piece... 10 out of 10, drop in, fit perfect no hassle. Just like an OEM would. 

Fit rating of this new BMC.... 9 out of 10... On the right rear of the piece, I cleaned off some plastic mold flash on the seat, not much

but it fit down much better than without. Still its a high quality part.. made in Italy.

Very comparible or better to a K & N.

So a thought.... I bet all these air filters fit 10 out of 10, when they were originally produced new, way back when.

But over time, tools wear and now the parts are close but not OEM close. 

I'm sure the companies dont want to spend much for tool maintenace or even possibly the part may need a new tool...

Cheers all

:beer:

I generally go for Hiflo as (like you said) they are very similar to OEM (and a lot cheaper).