Stephan wrote:tony.mon wrote:Stephan wrote:I did. My feel was little bit smoother run. As written above, BMC and KN don´t have this edge as well, and filtration is worse than paper filter ...
Are you talking about particle size or flow rate?
Just amount of dust coming trough the filter. But it is more theory, I found only one old test saying that KN filter prevent from 97% of debris, and paper filter 99% - what means that KN is 3times worse than paper filter. And if I look on filter, it looks like paper is more capable, at least I don´t see trough :-)
http://bmwmotorcycletech.info/K-and-N-filters.htm
But this is something very hard to prove - how it effects the engine health, I wouldn´t worry anyway. I tried BMC street filter but my bike runs better with paper hiflo.
You can't compare a mechanical filter, like a paper one, to a K+N which is oiled, and works by having larger voids between the cotton fibres, but coating them with sticky oil which attracts and traps and debris or detritus.
Simply looking through it isn't very scientific!
And paper filters (like vacuum cleaners) become less efficient at passing air through as they become clogged, whereas oiled filters (foam or cotton fibre) don't suffer as much; the flow rates are still better than standard even when they're quite dirty.
Paper filters pass less and less air as they become dirty in normal use, and less air flows through, leading to a richer mixture in extreme cases, but less power anyway as the engine has to work harder to suck air in; the air pressure on the post-filter side is at lower pressure for longer as the intake stroke progresses, and the engine gulps a large amount of air from the airbox. This lower pressure exists until the filter can flow enough air in to equalise pressure with atmospheric again.
If the intake valves have closed before the filter allows enough air through, then you have less volume/pressure air in the cylinder, hence lost power.
But simply putting a higher-flow filter into a bike often gives rise to problems, simply because most people don't reset the fuelling (jets and adjustments) to compensate for the higher flow/quicker recharge rate.
That's why you often hear people saying "I put in a BMC/K+N/other make filter and it ran worse, but when I put the standard one back in it was better".
They are simply running the wrong carburettor settings for the filter they have in.
To a degree the same can be said for race cans, but the engine's more tolerant on Storms of cans without jetting changes. If they revved higher it would become more of an issue.
Mine is properly jetted for its K+N, but if I put a standard one in I expect that the bike would run worse, simply because it's not set up for that filter.
To prove the theory, try running your bike with no filter for a couple of miles- as long as you aren't in the Sahara on a windy day it win't cause any damage for just a mile or two. The bike should be at it's best performance because there's nothing getting in the way of the air flow into the carbs. But what you'll find is that it runs lean, due to the "extra" air it's getting, compared to what it's set up to deal with. It could be jetted to suit the unfiltered air flow, but you'd have to rebuild your engine quite often due to bore and valve stem wear.
So in summary- anything you do which changes the way your engine breathes in or out should be followed by checking/adjusting fuelling to suit, otherwise it won't run properly.
Just my opinion, please feel free to offer yours.
It's not falling off, it's an upgrade opportunity.
If you have did you notice any difference. I've read what Burnie says, but would be interested to hear what your opinions are. I have heard some say doing this mod allows more dust to access the air filter. What's your opinions 
