K&N air filter

[JCBMW]

Anyone out there put one on an 1150RT? If so did it really make that much difference? I am considering getting one out of the pure fact that they last virtually forever, and the cost of normal replacements far exceeds that of one K&N one time. Input please.

[Joe Frickin' Friday]

Anyone out there put one on an 1150RT? If so did it really make that much difference? I am considering getting one out of the pure fact that they last virtually forever, and the cost of normal replacements far exceeds that of one K&N one time. Input please.

 

How much for a K&N? How long are you planning to own the bike?

 

As far as performance goes - I don't have any links, but it's been reported here that the R259 engine has been run without any filter, and the performance improvement (over having the stock filter installed) was not measurable. Maybe someone else can post links?

[jrlunsford]

I've had one on my 2000 1100RT and mileage wise I can't tell that much difference but as for as the power I can tell quite abit of difference but I guess anytime that an engine can breath better it gotta run better. I have that filter on all of my bikes and vehicles. The mileage on the vehicles seem to be a couple of miles to the gallon better.

[ShovelStrokeEd]

I'm wondering how you 'tell' that quite a bit of difference since the difference in flow rate is extremely small. (0.07% as I recall). The filter is less efficient at what it is supposed to do, which is filter the air coming into the engine. Performance gains, if any, would only show at the maximum flow rate of the motor. Since the R259 motor is not limited in peformance by intake flow, there should be no gain. Actually, that statement is wrong, the motor is limited by flow but it is at the ports due to the shape dictated by the engine configuration, not by the flow ratings of the upstream components or, for that matter, downstream (exhaust) components.

 

Fuel economy should be unchanged as well since the mixture is not dictated by flow through the filter but rather by throttle position and engine RPM.

 

Probably most of what people preceive as a performance gain comes form changing a clogged, or partially clogged stock filter for a new Whiz Bang filter. You could realize the same gains by changing to a new, stock filter. For me, the advantages of superior filtration, in terms of engine longevity, far outweigh the cost factor. I only change my filter once every 40K or so miles, or once a year whether I need it or not.

[timmr]

I put a K&N in my '04 6k miles ogo. At the 12k service the service manager gave me a hard time about it. Came home and did a search on this site for some info. Went back to the dealer the next day and bought an OEM filter and replaced the K&N. The K&N is for sale if you want it.

[Davis]

I guess anytime that an engine can breath better it gotta run better

 

While that may be true, changing the air filter to a less restrictive one will only result in an improvement if the air filter is restricting the air flow to start with. I can't find the webpage with the results (it may have been taken down), but Don Eilenberger and Brian Curry ran back to back to back to back Dyno runs on an R1100 with the stock air filter, no air filter and with half the stock filter covered with plastic wrap. The result, no change! Trading the reduced filtration of an impingement type filter might make sense if you get an increase in performance, but in the case of BMW motorcycles, you don't get an performance increase, just more dirt.

[philbytx]

One of many air filter comparo's gave the K&N a "so-so" rating due to it not being able to capture small particulate matter (can't remember the size data, sorry!). This is for both auto and bike applications. Yes, for race apps it works well but generally the motors are stripped after each event so wear and R&R isn't really an issue. They need H.P.!!!

 

For general use, the stock filter protects the motor more effectively and, in the case of our bikes, the K&N on its own offers no definitive and well documented improvement in performance nor increased/better air filtration.

 

I stick with stock filters in all my vehicles and change them every 6k at the most. Very easy to whip them out and check them.....except in my diesel Motorhome

[Joe Frickin' Friday]

They need H.P.!!!

 

Um, actually, they need sponsorship money. Judging from some math I did a while back, you might theoretically expect a performance gain of a fraction of a percent. But if you're on a professional race team, and you stick this filter in your bike (and their sticker on the fairing), the improvement in your race budget is fantastic.

[leikam]

Here's another vote for no difference. I put one on for the same reason you're considering and the seat-of-the-pants feel was the same. Several thousand miles later, I took it off and went back to stock. Performance again seemed unchanged. The reduced filtration ability of the K&N is what persuaded me to go back.

[Wooster]

I've a K&N air filter on my XR dirt bike and have zero complaints: at the same time, I've stock filters on my RTs. While some denigrate K&N's effectiveness at keeping certain small particles out of the combustion chamber, I've never found evidence of this with my dirt bike. FWIW, on oilhead beemers, I don't think any performance improvement comes from this singular modification. i.e., swapping out air filters; Honda XRs are another matter entirely.

So, if moved to do so, use a K&N airfilter; no harm, no foul (but also, no difference !).

 

Wooster who's OK with 10k mile stock airfilter purchases

[smiller]

I only change my filter once every 40K or so miles, or once a year whether I need it or not.

 

And this is probably one of the best reasons not to bother with the K&N. I agree with Ed's schedule (although I replace at about every 40k or every two years) and thus the cost of the paper filter is pretty insignificant. I'm not sure that the K&N filter will expose the engine to any wear issues, but why even take the chance when there is no performance increase, no (significant) cost benefit, and they're a PITA to clean? I just can't see any justification.

[Davis]

the cost of normal replacements far exceeds that of one K&N one time

 

Let's see K&N filter and oil is easily $50. I pull my stocker every oil change, tap it to knock off the loose/big stuff and replace it at a cost of $12 every 36k. Would be almost 180,000 miles before it saved me any money to change to K&N.

[Bob Palin]

I was talked into a K&N filter by the BMW shop near Boulder, CO. I can't tell any difference and I think I will switch back when I'm next due to change the filter.

[DavidEBSmith]

While that may be true, changing the air filter to a less restrictive one will only result in an improvement if the air filter is restricting the air flow to start with. I can't find the webpage with the results (it may have been taken down), but Don Eilenberger and Brian Curry ran back to back to back to back Dyno runs on an R1100 with the stock air filter, no air filter and with half the stock filter covered with plastic wrap. The result, no change! Trading the reduced filtration of an impingement type filter might make sense if you get an increase in performance, but in the case of BMW motorcycles, you don't get an performance increase, just more dirt.

 

Here ya go. DATA. (to quote Brian Curry).

 

For those too lazy to click on the link above, here's the dyno chart. Blue = K&N, red = used stock filter, green = no filter. Increased breathing is not a good reason to buy a K&N filter.

 

[Pilgrim]

K&N achieves its published HP numbers by testing with a clean filter; sometimes it's even unoiled.

 

A clean K&N will pass lots of air, and almost anything else up the size of pea gravel.

 

Like any other filter, they become more effective as they get dirtier(up to a point).

 

But as the filter dirties up and becomes more effective, the tradeoff is reduced airflow.

 

Incidentally, Mitch: Good point about sponsorship money.

 

Pilgrim

[Softtail]

I see that it is K&N bashing time again. Has to happen every so often. Well anyway, I have always used K&N filters on both my 2002 RT & 1991 FXSTC. So far, I have never had to do a premature upper-end, or any upper-end work for that matter. When I gaze into the airbox of the Beamer, there is no particulate matter. If the K&N filter addmits particles as large as pea gravel, as someone has suggested, one would expect to see tons of crap in there. K&N also makes a nifty oil filter that can be removed with a box end wrench. So, does any one want to take a shot at K&N oil filters? <<<<Softtail>>>>

[JCBMW]

Well in the spirit of indecisiveness (SP) I always feel that one should er the way of the masses. Thanx for all the input, guess I'll stick with normal replacements.

[Ken H.]

I see that it is K&N bashing time again. Has to happen every so often. <snip> When I gaze into the airbox of the Beamer, there is no particulate matter.

Yeah and I aways ask the same question, "How many microns can you see down to?"

 

Pea gravel may be a bit of an exaggeration but the ability to filter down to only 40 microns vs. 5 certainly is not.

 

Clean air good, dirty air bad. Seems pretty simple to me!

[jm1515]

Anybody ever heard of or have experience w/ these guys???

 

http://www.bmcairfilters.com/products.asp

[outpost22]

Well, we can all make claims for and against. However, I have run the K&N for many years. The simple reason? They save me a lot of money, and no, there weren't any top end rebuilds required due to dirty air either.

 

In my truck, the stock filter costs about $15.00 ea. and I would replace them every 4 months. After almost 6 years x $15.00x 3 changes/year for a paper filter, thats $270.00 in air filters vs. the origial $42.00 for the K&N. With the K&N that cost $42.00, that remains a fixed cost.

 

Now when I apply that to ALL my vehicles (which I normally keep a long time), it adds up to a great savings.

 

My R1100 came with a K&N from the previous owner, and I'm keeping it for the long haul

[GordonB]

Let's get back to $ & cents, BMW paper filter costs maybe $12 to $15...

At 12,000 miles between filter changes figure about a year for most riders between filter changes.....

C'mon guys are we that poor that we need a way to find adtl savings on a $12.00 item over 12 months?????

We spend $18,000 bucks or so on a BMW and we quibble about plugs and filters