Put the OEM filter back in...?

Also, 98HP? You mean 85HP?

 

Yeah after motorbike purchase I had 98HP (checked)! After installing K&N I wasted around 10-15 HP [] (didn't check but I feel it)

 

I would leave the motor stock unless you enjoy playing engineer, spending money and time on a project that is not going to improve your bike.

The K&N filter leans the fuel/air mixture but the EFI would compensate for that and should not affect the power output. Your fuel mileage is probably also down.

Removing the CAT from the stock can is the cheapest mod and will give the bike a very clean, crisp throttle response, w/o hurting fuel mileage.

IMO, ANY vehicle that is completely stock is more valuable than all the hop-up gadgets one may put on a vehicle; but for many, its' enjoyment and that's good.

I know you are not interested in hearing my response, but most do more harm than good in trying to 'improve' the performance of their bike. Good luck with your project bike.

 

I would leave the motor stock unless you enjoy playing engineer, spending money and time on a project that is not going to improve your bike.

The K&N filter leans the fuel/air mixture but the EFI would compensate for that and should not affect the power output. Your fuel mileage is probably also down.

As for MPG the only way an air filter can improve MPG is to trick the engine into breathing more air for the same fuel as compared to before. That is easy enough with carbureted engines but your EFI is not going to let that happen. The K&N provides less restriction, no one doubts that. However any restriction not provided by the K&N will be provided by your right hand closing the throttle. We're right back to the fact you need the same amount of air and fuel for a given power level no matter what air filter.

Often a leaner mixture will produce more HP. But on an emission controlled engine which is already on the borderline of acceptable leanness thats not going to happen. Most tuners will jet an off road dirtbike on the rich side "because it runs better that way." Rich is more forgiving over a wider range of operation. But leaner not only produces better MPG but more HP.

K&N claims miracles in producing lower restriction in the same size package as stock. They do it by filtering poorer than the stock unit. Count the number of pleats in your K&N filter, not many so its easy. Count the pleats in your OE paper filter. Hard because there are so many. Easiest to just count one inch's worth and measure the filter to get total count by multiplying. If BMW saw a need for lower air filter restriction then all they would have to do is provide a bigger air filter. Increase the X and/or Y dimension. Or the Z thickness. Fairly easy to do. But K&N uses about 10x less surface area and gets lower restrictions? The only way to do that is to make a filter consisting mostly of holes. Lots of holes. Big holes. Big holes let dirt through.

 

Leaving aside all the pointless blather about what you should or shouldn't be allowed to do with your own bike :blah:, I'd say the K&N is unlikely to make that much of a noticeable difference on its own.

If it was me I'd be back in there looking to see if I'd cocked something up on re-assembly after fitting the new filter that was causing some obstruction. If nothing was found I'd stick the stock filter back in to confirm everything went back to how it was before. Then I'd try the K&N again.

If you did go down the PC and custom mapping route you'd get re-assurance that all was well - at the very least.


nicko

 

Ok, will try. BTW I have never used power commander, how looks tuning with PCIII for F800? Anybody tried?

 

great avatar jakub! [thumb]

 

K&N filters have ruined more fuel system components than you can count. When I worked for Porsche/Audi we did a brisk business replacing such items as mass airflow sensors that were gummed up with K&N oil, clogged with dirt not caught by K&N filters, or burned out when both of the above got on their delicate electrical bits.

So putting a really bad filter on your bike and then spending more money to try to tune it back to where it was when stock strikes me as a losing proposition. Put the stock air filter back in and work on your riding technique, which will improve your bike's performance 100 times more effectively than any bolt-on aftermarket parts.

-dan

 

'Pointless blather, huh? uke: As I said, if he enjoys it, do it! It's his bike.

Personally, I will never put a K&N filter on ANY vehicle of mine and I certainly will never buy a vehicle that has a K&N. They pass more dirt...... period.

My vehicles run flawlessly in stock condition because I keep all the fluids in good repair and don't try to alter the intake/exhaust, or fuel system in any way. I'm not that smart, or rich. []

 

I guess I'm somewhere in the middle because I don't disapprove of mods that improve on the inevitable compromises inherent in mass production.

But there are smart mods and there are dumb ones and I've already made clear which I think K&N is.

-dan

 

As Fred said, you have a right to do whatever you like with your bike BUT there is no way you got 98HP. I doubt you could get that at the crank. Where in the heck did you get that figure from anyway? Seat of the pants measurements are notoriously inaccurate. I am puzzled about why you wanted to go to a K&N in the first place. Do you already have a power commander installed? If not, why would you pay $500 plus to correct what you could do by replacing the stock filter? I am also a tinker but I generally leave the engine stock. This bike has a lean burn engine and I get 53 or 54 MPG average which to me is more important than 5 more HP anyway.

 

I have done the K&N with a PCIII - in both cases to free things up a bit
Can't add much as far as the pro's and cons mentioned above but have had no bad experiences with K&N's on other bikes I've owned

I 2nd the opinion above that it's extremely unlikely your bike actually ever made 98hp stock, do some reading but that number isn't even reached with tweaked motors (not that anyone really tunes these rotax donks beyond the aforementioned filter, exhaust and PCIII).
Even all that with a full $2k titanium Akrapovic is unlikely to reach the 90's.

 

I have a K&N Filter on my f800s I bought for a good price, I like it, I do like modifying my bike, sure stock standard was fine, but while im earning money this is something I like to spend my money on, besides it beats roaming shopping malls.
My thoughts were if they put K&N filters in dirt rally cars with engines worth thousands of dollars they can't be to bad I have spoken to a mechanic who has worked on these engines and he has no hesitation about using them, even for his own car engines. The company has been around for years, im sure if there was a problem they would be out of business by now.

I don't know why 'kubagsx' would be experiencing the problems he is though, although Im not into the dyno stuff, my bike does have a bit of get up and go when changing gears when having put the K&N filter in, kind of noticable like when I put my aftermarket exhaust on. Or different thing but noticeable difference when I put some hyperpro springs in the front forks. Or REALLY noticeable putting a HID front light in, or a LOUD stebel horn.

 

Ah heck, all along I thought it was a pussy cat. Abbreviations are getting out of control. It used to be that you could tell what a business did by it's name. Not so easy now. KFC? IHOP? My mom once asked me what kind of a stupid person named their business, "I hop".

 

You gotta' love acronyms. For anyone who has ever been in the military will confirm this. Acronyms are used in practically every sentence in their vocabulary.

On the subject of K&N filters, my feelings are if you have 2 identical motors, 1 has a factory filter while the other has a K&N, the factory engine will be running stronger, at say the 50K mark.
Both engines will still be running fine, but a dyno will show the factory engine running stronger. Many will disagree with this opinion as nitpicking.........................................that's mine. [:0]

 

So your saying anything under the 5k the K&N will let the engine breath better, anything 'say'over 5k the factory filter will make the engine breath better?. what i noticed and my husband disputes my finding is with the factory filter in travelling at 120km the revs sit at 5000 with the K&N filter if im travelling at 120km REV'S AR AT 4K and a bit.

 

One symptom of an engine ingesting dirt is the intake valve seat wears faster than the exhaust, causing the valve stem to rise, closing the gap at the shim.

If you have a K&N filter and the intake valves are holding their adjustment then you are probably not doing any extra damage. I don't have enough F800 experience to state how much adjustment is normal for the valves, and whether the intake and exhaust normally wear the same or different. Perhaps someone else can chime in?

 

I see what you are saying, your opinion is that the engine with a stock filter will be running stonger (better) after 50,000kms.
As far as my observations, at how many revs im sitting in a certain gear/speed with the K&N filter in, my husband has now explained the same thing as you, so..... im hallucinating then [:I]
I'm not aiming my enquiry for a arguement, I'm just trying to get my head around things....its a female brain thing[err] plus it seems everyone has such polar different opinions on aftermarket air filters I want to make an informed decision about what im doing to the motor.

 

I like the theory of breathing better, I guess you'd be able to quantify it by feeling the bike pull stronger at given throttle and being a shade more enthusiastic when you do crack open the gas.

In all honesty the BMW ones work fine and I doubt you'd notice any difference, unlike the old days when you pulled a car sized filter off and replaced it with K&N pods
And as mentioned here the revs / speed won't change, but in the presence of more power you'd be able to maintain that speed up a hill easier without downshifting

 

I like the theory of breathing better, I guess you'd be able to quantify it by feeling the bike pull stronger at given throttle and being a shade more enthusiastic when you do crack open the gas.

What is your basis for "liking the theory of breathing better"? For any given speed or HP output your engine needs approximately 14 mass units of air to every mass unit of fuel. Doesn't matter what air filter you are using. If an air filter "breathes better" then you are going to close the throttle to compensate to maintain that exact same mass flow of air.

The only HP advantage to be had is at full throttle where more air will permit the addition of more fuel for more HP. Remember that dyno runs are made at full throttle at all RPMs plotted so finding "more HP" at 4,000 RPM on a dyno plot means nothing when on the road.

 

Breathing better will produce more torque so I have to agree in this instance with Phil, you might notice an improvement when going up hills and not having to down shift as often.

 

My point is the factory unit filters better, IMHO, the engine ingests cleaner air and will last longer because it has led a 'cleaner' life to the 50K mark.

A K&N ad years ago said 'the dirtier our filters get, the better it filters' because as the dirt piles up, there is more surface area (the dirt pileup) to act as additional filtering medium. I see their point, but never adopted that train of thought.
Years ago I put a K&N on a 1980 750F. It simply would not run with that filter because it was so leaned out with the freer flowing K&N. They pass much more air and dirt, in my mind. The paper element is used by most, if not all vehicle manufacturers for a reason.

K&N is very popular.............so they probably are not as bad as I envision, but I am not comfortable using them. Dirt is the mortal enemy to any engine and it's oil. I'll spend the extra money and stay factory. []

 

Fred,

That K&N ad always made me laugh. So how is that different from the OEM filter, which also clogs up as it traps dirt? I might edit the ad a bit to say, "Our filter won't trap for crap until it gets dirty, at which point it almost does as good a job as the factory one."

I don't know about the 1980 Honda, but my old '74 750 K4 had a very restrictive airbox, designed to limit intake noise. Modifying that produced a lot more airflow than stock without allowing more dirt into the engine. I had to re-jet a little to make up for it. Hondas with carbs were (and are) known for running at the hairy edge of lean. My friend's 2009 VTX 1300c requires prodigious amounts of choke when it's less than fully warmed up.

-dan

 

Agreed on most counts, the first thing any engine tuner does is look at any impediments to air flowing in and exhaust flowing out.
In the old days it was easy to improve on, but as many shade tree mechanics have found out, modern air box designs have a lot of science behind them and aren't easily improved upon (unlike the aforementioned K&N pods of old).
Less restriction to airflow at any throttle opening will have some affect, and you would probably be right that it would be most noticeable at full throttle and quite possibly imperceptable at less.

 

Dan, I agree, that would be a more accurate wording of their ad and in a round about way, saying the same thing.
Money savings is the only real reason people go the K&N route and I feel a compromise, with less than ideal filtering.
Engines are sensitive to intake/exhaust pressures/vacuums, changing any of that affects performance and drive ability, usually for the worse.

 

Money savings ?

Not such a valid reason on the F800 - might break even in about 40k miles based on one clean of the K&N I guess. A lot of people don't even seem to keep their bikes that long.... Not on here lately anyhow [uhoh]

nicko

 

Money savings ?

Not such a valid reason on the F800 - might break even in about 40k miles based on one clean of the K&N I guess. A lot of people don't even seem to keep their bikes that long.... Not on here lately anyhow [uhoh]

A K&N is $44 from F800Depot, OE is under $18 at Bike Bandit, and OEM is $12.50 at beemerboneyard.com. A K&N FilterCharger kit for washing and reoiling a K&N is $15. Is good for several treatments if you don't lose it between uses, or that it just gets too old.

At those prices one will never save money with a K&N. Especially if one's labor is worth more than minimum wage. Plus remember the K&N needs to dry before new oil is applied. And that new oil needs to take a set and dry before riding. Your bike will be out for 24 hours getting a K&N washed. This is why I have at least 2 foam air filters for each of my dirtbikes. Its not that I can't do without for a day but when I've got the thing open and one filter comes out I want a fresh filter to put in RIGHT NOW rather than leave the bike open.

While that sounds good, I usually wait until I have two dirty filters because its no harder to wash 2 than one. The time for setup and teardown for cleaning is the hardest part. Even with NoToil using the bathtub.

 

Hi guys,
after reading this biiig thread, i'll add my personal experience and I will also ask for a piece of advice you.

I ride a '07 F800ST, graphitan with 64.000km. It has Ohlins inside the front fork, HID and (here's the important part) a K&N filter and and Akrapovic titanium exhaust.
I removed the CAT when I fitted the K&N and the first thing I noticed is that, as somemone told, the bike "breathes better". When i say "breathe" I mean the bike is like it has more power in lower revs. I can easily use 6th gear at 50km/h. Not sure if the cause is the K&N or the removed CAT. The bike is simply 'easier' to ride, in terms that the engine allows you to be more 'lazy' in terms of gears. It has increased acceleration (with the baffle out) and fuel economy is about he same. I can roll at 120-130km/h, packed and with my girl as the OBC shows 4.5lt/100km.
Regarding to filtering "worse" that others, it should be true, i guess... It if lets more air flow, the air must go through somewhere lol... Tiny holes. Lots of them. The thing is I don't use my bike offroad (it's a road bike...) and I don't get a lot of dirt where I ride. Most hazardous 'bit's' get sticked in the oil, you just gotta make sure you keep it clean and perfectly oiled. Not too much , no too less oil.

1 thing I noticed and I'd like to hear from you guys. It backfires. Omg it backfires like it ate like a full stock of tacos! When I pop down a gear or when I simply shut the gas. I've asked a friend and he says that I should take the bike to a dealer and take a look at the ECU, because the 'popcorn' I hear inside the pipe is gas which didn't burn when i shut the throttle. My question is, shouldn't the ECU adjust itself? I also hear it has a certain threshold from which it can't adjust anymore. Makes sense, since I have my exhaust line fully open.

Oh and the bikes keeps dying on me, when already hot. I've reprogrammed the air valve, but it keeps doin' the same thing .

Any words of wisdom?

Ride safe!

 

Popping and backfiring I believe is something the engine probably does with the stock pipe - but it's just that you can't hear it (happy to hear a more informed opinion on that subject)

And cwo4usn - to be honest if you are happy with the sound and have no desire to play with fuelling and airfilters then there is probably no value in tinkering with anything else, leave it stock. Maybe a booster plug if the reports of it filling in the 4k dip are correct, truth is you probably don't notice that dip but you would after it was gone.

The CAT is built into the front of the stock cannon, so there is no way of removing it without cutting open the pipe and welding it back up.
I'm actually in favour of emissions controls in general, and if the factory spends the $$$ it's possible for it have virtually no impact on performance, in my case I had a dinged can and a dislike of the stock sound

 

Popping and backfiring I believe is something the engine probably does with the stock pipe - but it's just that you can't hear it (happy to hear a more informed opinion on that subject)

Consider yourself corrected. The stock system does not pop on deceleration.

Deceleration popping is not a backfire. A backfire would mostly destroy your air filter.

Deceleration popping can be caused by several things. Usually it is a late combustion of an overly lean mixture. Waits until after the exhaust valve is open.

An air leak in the exhaust, usually at the cylinder head junction, can add enough air to the hot gasses for additional combustion in the exhaust.

A poorly made exhaust, or one with excessive carbon buildup, can cause deceleration popping. A sloppy weld with a tab sticking out in the exhaust flow will be hotter than the rest of the exhaust and can ignite unburned lean mixtures. A layer of carbon can do the same.

A new exhaust can result in deceleration popping due to excessively lean mixture due to operation outside the range the ECU can compensate.

 

Hello agina mates,
gonadz pls allow me to disagree. In my F800ST the CAT is inside the stock can. Pipes are clear.
the CAT supplied with the akro fits in the junction between the pipes and the exhaust can.
Regarding that 4k rpm well.. It a looooot better after exhaust and filter!!

Cheers mates! Oh and ride safe!

 

I feel you may have misunderstood my reply as that was exactly what I was saying (cannon being a mildly derogatory description of the stock muffler).

I like the way Akrapovic did that with their mini cat, not sure how well it would flow.
There doesn't seem to be many aftermarket exhausts that have a CAT, who knows how that will play out with legislation as the years roll by - I suspect the beaurocrats will fix that gap eventually.

I only noticed the 4k dip vanish after I fitted a PCIII, filter and end can didn't make much difference on their own as they had little impact on the fuelling