IR your motor should be thought of as a air pump,it breaths in and out.You've allowed it to breath out better by using the dyna,but the piston forces the exhaust out under pressure.when the exhaust valve opens there is still about 100 psi in the cylinder and the piston hasn't even reached the bottom of the power stroke and started up yet.the intake is another matter,fuel is drawn in only by the vacuum formed by the piston moving downward and the 14.7 psia of atmospheric pressure moving threw the filter and carb.to help keep things in balance using a less restrictive air filter can help.The more pleats in a filter the more restrictive ,both the K&S and Oldfeller's have no pleats,I just think Oldfeller's does a better job of filtering.

batman wrote on 02/16/17 at 01:20:56:


I don't agree with that statement.  The pleats (folds) in the air filter element allows the filter assembly to have more surface area of the filter media.....and this allows the air to move through the larger surface area more easily.  If the filter media had 90 degree folds in the paper, and the surface of the filter media was oriented so that the surface was alternating at a 45 degree angle to the air flow path.......the surface area would have 41% more flow area than a flat surface would.  If you look at the attached photo you can see that the folds are actually much tighter than 90 degrees, and the amount of the surface area is most likely close to twice the area that it would have if the filter was a single flat sheet.

The ability of the K&N (and Oldfellers filter) to move air through with less restriction is a function of the different filter styles - not a result of folded vs. flat.  The paper element traps dirt by the use of very tiny openings in the paper element.  The dirt is too large to pass through the holes in the paper, and it gets lodged in the small holes.  As the paper filter gets dirty and the holes close up...the filter becomes more restrictive and eventually it will not flow any air   The oiled foam filters, oiled gauze filters like the K&N, and Oldfellers oiled batting capture the dirt in the oil coated surfaces of the filters media.  The openings are much larger and the dirty air can pass though easily - but in the process the air has to make a lot of turns and twists to get around the media - as the air is making all these turns the dirt bumps into the oily surface of the membrane, and the dirt gets stuck in the oil...the cleaned air continues to flow through the filter and into the engine.  When these filters get dirty they don't get a lot more restrictive - but dirt can begin to pass through the filter if the oily surfaces are all coated with dirt and no longer sticky.

Most street bikes/cars/trucks use paper filters as they work well, and the air encountered on a highway isn't very dirty in most areas - the paper elements can last a very long time.  Most off road motorcycles use foam filters as they are very easy to clean and reuse, and in dirty conditions these filters may have to be cleaned daily.  The foam elements are pretty affordable and you can own a spare or two and use one while you clean the other one.  The K&N filters are not original equipment on anything that I can think of.....they are expensive, cumbersome to clean and oil, and for most equipment there are easier options.  K&N has made a good industry for themselves.......they are good filters....they just aren't convenient to own and maintain as you need a special spray cleaner, then you need to let them dry, and then you need to spray the special oil on them.  (Foam filters can be washed with dish washing soap, and they do make special "tacky" filter oils....in the old days the manuals told you to use motor oil).

           

dave I guess we'll have to agree to disagree,on pleats ,a builder/racer of Suzuki drag bikes said he picks the filter with the fewest pleats as the ones he uses because they are less restrictive. It may be because the air has to change the angle of flow twice and the points of each fold are somewhat compressed and don't flow as well as the straight sides of the pleat,I'm not sure,but he must have had some logic.I'm thinking more pleats means the air needs to take a more drastic angle through the panels and more pleats means more points where the flow is restricted.If you 've taken a stock air filter apart you find that the paper is one sheet and folded ,so I believe the peaks and valleys must be somewhat compressed.while the surface area of a pleated filter is much larger than a flat panel it remains to be seen how much of that area is really effective, and how restrictive is the paper itself?while a filter with more pleats may have more surface area and therefore a longer "life" it may also be more restrictive than one with fewer pleats.

Dave, I don't spend much time there myself,but I'm in the process of building a tuned intake ,and with VE approaching 130% I don't feel a paper filter of stock size is up to the task.The length of the intake I use will determine the RPM ranges that will give me the extra boost and are not at WOT ,but will require the intake to carry higher than normal volumes .You yourself use a foam filter,why not a cone? could it be better filtration and less restriction?the drag strip isn't the dirtiest place to run a bike either,I think the man wants to protect his expensive motor,but also wants a less  restrictive filter,in a standard size that can be changed often and quickly.

I hear you. A few weeks ago I went to get a can of compressed air after I had got the filter out, when I came back, the gf had put the bike back together without realising that I had the filter out ,(in fact I had it with me because I was at first going to go to the service station to give it a blast) and she drove off. I was a bit cross about that but she didn't even notice the difference!


gizzo wrote on 02/17/17 at 02:39:33:

Woah! Bullet dodged!

tl;dr Women are fun.

I was just going to say, only a note on the vital component will work. More b'ground on my story...

The gf keeps telling me that she wants to learn to do the valves or oil, I tell her 'believe me you don't want to do the valves' but sure you can do the oil but interest drops away when the time comes. A while back the bolt that holds seat on at the back worked it's way off, when I noticed that, I bought another one and gave it to her and said, 'ok here's your bolt (it's her bike btw) go and put it on. She goes out to the bike and comes back in 5 minutes later saying she can't get it on. What do you mean you can't get it on it just screws in, I can't get it on, it won't go on I don't know it just won't go on. I take the bolt go out come back 18 seconds later and tell her OK it's on, perhaps we should go out together and see what the problem was. No she doesn't want to do that.

OK put all that on the shelf for the moment. Right so now you have some context, I'm gone with the filter, it's early in the morning she is still asleep, the seat is off, the side over is off the plastic cover is off all various bolts are in a pile with some tools. On my way home a bike is coming towards me and I get a quick wave, I'm on the GS and I wasn't paying attention to the bike, at first I thought is that the S40, then I thought no, couldn't have been, not possible, I've got a modulator on the GS so it's not unusual for people to shout at me or point at me yelling out that there's something wrong with my headlight.

Then I get home and see the bike gone. Moment of confusion, does not compute, this cannot be, not possible, error error, danger Will Robinson. Fortunately she was going to go for a fang but came back. I didn't quite know how to broach this particular conversation that we were about to have. I didn't say anything for a while as I gathered my thoughts, I was just happy the bike was back, I had some terrible visions of what could have happened. I thought it was prudent to just calmly and quietly say... 'glad you saw me because you know there's no air filter in the bike I was taking it to get air blasted'. Straight away she's on the defensive with 'well I didn't know'. I excused myself so I could fume privately and get it all out of my system, when I returned I decided to just gently probe her reasoning. I was genuinely curious as to the thought process involved in seeing the bike in pieces with tools all around it and put it back together when you've never done anything to it, and then just ride off. I thought this was a golden opportunity to delve into the usually inscrutable thought processes of the curvy people. So I needed to remain calm so as not to miss this rare occurrence.

I said again, 'I'm glad you came back because there's no air filter in the bike', immediately she shot back (again) with 'well I didn't know'. Hmmm this wasn't going to be easy... 'didn't you suspect that I was working on the bike seeing as it was in pieces', I innocently inquire. The next bit was priceless, 'I thought you were just teaching me a lesson'. 'What do you mean', I quizzically ask, 'teach you a lesson'. Maybe any women readers here will understand this logic but I confess I was getting more curious by the minute. How does that work? 'You know you take all this stuff off the bike and go out and if I want to ride it then I have to put it together myself'. 'Why the fu...' No let's start again, 'But darling, that doesn't quite make sense seeing as you were completely unable to put the seat bolt in, why would I suspect that you would suddenly be able to reassemble the bike bits, of which the easiest part was the final seat bolt?

After a while I changed tack. 'Well I am amazed that you got all the bits on, at first it took me a while to find all the bolts' locations'. By the way, didn't you see there was no filter in?'. No, she did not notice that. Which is not surprising seeing as she'd never seen it dismantled. 'OK, how about that extra bolt that was left over in the pile, did you not wonder where it went?'. No she did not.

'So let me get this straight, you've never seen the bike being dismantled in any degree, you then attempt to reassemble it on your own without me knowing, you have a bolt over that you don't know where it goes but you get on the bike and ride off anyway' er... 'weren't you concerned about that bolt, I mean maybe it was important'. No that did not occur to her, apparently. Fascinated at this blithe disregard for dying in an horrible grisly road accident, I soldiered on with my interrogation.... but it all got a bit too much and I had to just accept the fact that even after 29 years spending almost all my time with this woman and knowing her thought processes to an intimate degree, she is still able to confound and perplex me with little peeks into the enigma machine that is the mind of the female person. I guess that is why we love them, eh?