delta, the post you link states "a paper airfilter actually filters better when it gets older and is at its best, just before it clogs up". that makes sense as it lets through less, and only smaller particles. but what's the influence on air flow? i would expect that an older, more clogged up paper filter lets through less air, as well. i haven't seen anything on the effect of that, have you?
Gee, I do not know much about flow, except that back then in their advertisement material K&N made a big thing about it (but so did Dyna about their 36.000 Volts
). Anyway, I took a dive in my archives and if you're interested, I can scan K&N's (actually Efka's, who was the importer) 4 page folder for you about the K&N filter program that lists what models were available for what bikes. It's a looong time ago, but I remember only their oval model R 82 (R 83 for the CB550) would have had the benefit of my doubt. Glad I didn't do it, because I would have had a lot more intake noise under my butt.
The standard filter I run, has been in there for I don't know how many years and is still good. My test is simple: at various rpm I remove it to check if rpm changes. So far no changes and if my bike still does 170 km/h on the road (180+ km/h on the Dyno) there's no worry, is there? Now that I've found K&N's old folder again, I read something interesting:
K&N only need to be cleaned when there's on the outside a really thick layer of dirt. Recommended interval for cleaning: 1. road use: every 50.000 - 60.000 km, 2, dusty roads: 30.000 - 40.000 km. [my translation]. I've always been very prudent about the lifetime of the standard paper filter by saying: it does easily 18.000 kms but now having read what K&N says (and after what I've learned from airfilter specialists), I don't see why my standard paper filter element couldn't serve 50.000 km. I have planned to put mine to the test. In a box in the basement I still have several that I can use thereafter. BTW, I've never changed a filter element because it was clogged. I always did it before I went for a holiday, simply because I didn't know how many kms I would ride. The longest holiday ride I did, was over 10.000 kms in six weeks.
I can't understand why people would choose an inferior foam filter that can tear (and it will), needs oil (how much?/how little?) is inferior in its filtering from the start, where a genuine filter, if needed, can be replaced within 12 seconds and this includes opening the seat, removing the tooltray, the cover, the clip etc. and yes I've timed this). The only thing CB5
50 owners have to watch is that their filter is not fouled by the breatherfilter/separator that's notorious for fouling/wettening airfilters on a wide variety of motorcycles. Shall I scan that K&N folder for you?
