Increase in MPG/K&N

[dcurzon]

I replaced my air filter recently, to a K&N.  Primarily because i'm quite lazy and dont want to have to keep changing filters every 6000 miles or whatever the interval should be...  it was £32 give or take.  an OEM filter is somewhere in the region of a tenner, so assuming i do 12,000 miles a year, it would take me 18 months to recoup the cost of the filter.
 
But my MPG has gone up, from 54mpg to 57mpg.  Again, assuming 12,000 miles per year and fuel at 129.9, that's a saving of £69.07 in 12 months... Or,  across the same period of 18 months, £104.
 
So a £32 outlay for me over an 18month period saves £104 (18 months fuel, break-even on the filter)
 
50,000 miles (4 years) before the K&N needs servicing, in that mileage, i should save £287.78 in fuel, plus 8 air filter changes.
 
So if anyone is undecided wether to fit a K&N or not, hopefully the figures would suggest that it is worth the initial cost.
 
* i also replaced my tyres, which may also contribute to the mpg increase

[midden]

new tyres generally decrease MPG........So I read the other day.......
Have you checked your plugs to see if you'e running lean?

[fazersharp]

People on here say that the fazer runs rich so putting in a more free flowing k&N sorts that out, which you have shown in your MPG
What I want to know is why did they tune it to run rich, there must of been a good reason, so by fitting a K&N are you not "braking" what the factory made.
Ive only just changed my filter at 16,000 miles to another OEM one, and didnt notice any difference in performance, do not know if the MPG was affected or not, as have not checked.
Not sure wher you got the 6000 change filter from I always thought it was 12000

[richfzs]

Why would new tyres decrease mpg?

[Fazerider]

Why would new tyres decrease mpg?

When the tread is deep the rubber blocks will have slightly more movement so will dissipate more energy.
Also the diameter of the tyre is larger so the odometer will read slightly lower giving an apparent reduction in mileage.

[richfzs]

The second bit makes some sense.

The first one though, I put winter tyres on the cage, which have blocks so soft you can move them with a single finger pressure, and get no difference in mileage between winter and summer (always filling the tank, and recording mileage at each fill), so am struggling to believe that one, especially as the blocks on most bike tyres are so large...

Thanks for answering :-)

[fazersharp]

The first one though, I put winter tyres on the cage, which have blocks so soft you can move them with a single finger pressure, and get no difference in mileage between winter and summer

Could this be that your winter driving is different,slower, softer acceleration, due to ice ect. And so that compensates for the extra fuel the winter tyres take, also do you have air con in the summer and then not in the winter. 

[richfzs]

Never switch the aircon on, so not that. Suppose driving style may change slightly - but the winter tyres are on from (roughly) mid Nov  to mid march, and there's only ice as such on a fraction of that time. Roads are of course generally greasier though, so maybe. (and when it is properly icy/snowy, I am often guilty of enjoyment - rear wheel drive is great fun, at the expense of fuel :-))

[darrsi]

There's less bike tyre touching the road when new than when squared off so they should be more efficient when new if inflated correctly!

[dcurzon]

People on here say that the fazer runs rich so putting in a more free flowing k&N sorts that out, which you have shown in your MPG
What I want to know is why did they tune it to run rich, there must of been a good reason, so by fitting a K&N are you not "braking" what the factory made.
Ive only just changed my filter at 16,000 miles to another OEM one, and didnt notice any difference in performance, do not know if the MPG was affected or not, as have not checked.
Not sure wher you got the 6000 change filter from I always thought it was 12000

i was guessing the filter change service life... i have no idea what it should be

[Fazerider]

Does everyone who has fitted a K&N filter notice an improvement in long-term fuel economy?
It may be freer-flowing, but should that make a difference?
The mixture is regulated by the carbs themselves according to the velocity and density of the air passing through, the throttle doesn't spit in a set quantity of fuel dependent on how far you twist the grip.
MPG is dependent on so many things: rider behaviour, road conditions, how fresh the oil is, temperature, tyres etc., that it is hard to point a finger at a particular item and say it's responsible for an increase in economy unless all the other factors can be eliminated.

[darrsi]

Does everyone who has fitted a K&N filter notice an improvement in long-term fuel economy?
It may be freer-flowing, but should that make a difference?
The mixture is regulated by the carbs themselves according to the velocity and density of the air passing through, the throttle doesn't spit in a set quantity of fuel dependent on how far you twist the grip.
MPG is dependent on so many things: rider behaviour, road conditions, how fresh the oil is, temperature, tyres etc., that it is hard to point a finger at a particular item and say it's responsible for an increase in economy unless all the other factors can be eliminated.

Just a general breathing difference i reckon, with much better throttle response, which to me is a huge improvement in itself.

[His Dudeness]

Have to say I don't buy mgp numbers in general. Can you really measure mileage and fuel consumption accurately enough see a 3mpg difference?

[His Dudeness]

posted twice

[dcurzon]

Well I've been putting the figures into the spreadsheet since September so I'd say yes.

[mtread]

I haven't measured mine before and after exactly, but my mpg seems to have gotten better since the K&N went in. My mainly town regular commute is turning out about 55mpg. And performance is notably better. Haven't looked at the plugs.

[stevierst]

Have to say I don't buy mgp numbers in general. Can you really measure mileage and fuel consumption accurately enough see a 3mpg difference?

I've been using the fuelly app to help with my last 3 bikes, it's quite accurate tbh.

[darrsi]

Have to say I don't buy mgp numbers in general. Can you really measure mileage and fuel consumption accurately enough see a 3mpg difference?

No, it means nothing to me at all, which is why i have no idea what fuel my bike uses,'cos if you have daily traffic compared to a motorway run there's no comparison at all.
I fill up when needed, money isn't an issue with an empty tank!

[midden]

Why would new tyres decrease mpg?

scroll half way down
http://www.bridgestonetrucktires.com/us_eng/real/magazines/ra_special-edit_4/ra_special4_fuel-tires.asp
Seems a good reason to buy part worn tyres and and not to change tyres until legal min tread limit reached

[richfzs]

Interesting read, thanks midden. I think the engineering within, and forces on, the tyre, are somewhat different from the truck tyres discussed to ours though! A touch tyre starts out with a huge tread depth for starters (sure someone will know how deep), so a very different thing.

[darrsi]

Interesting read, thanks midden. I think the engineering within, and forces on, the tyre, are somewhat different from the truck tyres discussed to ours though! A touch tyre starts out with a huge tread depth for starters (sure someone will know how deep), so a very different thing.

There's no way you can compare car/truck tyres against a bike tyre as bike tyres barely touch the ground so have much less drag, hence the reason cars are so much better around corners, the reason they benefit is because they have the bigger engine to compensate, and also why fitting larger tyres to your bike is not necessarily such a good thing.

[fazersharp]

From my first post I still a question.
 What I want to know is why did they tune the fazer to run rich, there must of been a good reason, so by fitting a K&N are you not "braking" the tuning the factory made.
I've only just changed my filter at 16,000 miles to another OEM one, and didn't notice any difference in performance,
So far I only read darrsi has seen a difference in performance with the K&N filter has anyone else seen a difference?.
My brain cogs are thinking if I saw no difference from a 16000k - 15 year old one to new oem then why would I expect to see a difference from an original to a K&N, I fear that any difference felt is physiological.

[darrsi]

From my first post I still a question.
 What I want to know is why did they tune the fazer to run rich, there must of been a good reason, so by fitting a K&N are you not "braking" the tuning the factory made.
I've only just changed my filter at 16,000 miles to another OEM one, and didn't notice any difference in performance,
So far I only read darrsi has seen a difference in performance with the K&N filter has anyone else seen a difference?.
My brain cogs are thinking if I saw no difference from a 16000k - 15 year old one to new oem then why would I expect to see a difference from an original to a K&N, I fear that any difference felt is physiological.

The K&N isn't as filtered as other brands, it literally lets more air in and these bikes seem to love it.
As to why they were originally rich, who knows, but the fact is they work really well with only positive side effects.

[fazersharp]

Yep I hear you.
But is there anyone else on this forum who has fitted one (on a fzs 600 ) and seen a difference.
You see I am biased because I have just fitted an OEM one and dont want to feel ive made ---- not a mistake, but missed a trick by not fitting a K&N one, And so far there is only one person saying they saw a difference.

[Fazerider]

From my first post I still a question.
 What I want to know is why did they tune the fazer to run rich, there must of been a good reason, so by fitting a K&N are you not "braking" the tuning the factory made.
I've only just changed my filter at 16,000 miles to another OEM one, and didn't notice any difference in performance,
So far I only read darrsi has seen a difference in performance with the K&N filter has anyone else seen a difference?.
My brain cogs are thinking if I saw no difference from a 16000k - 15 year old one to new oem then why would I expect to see a difference from an original to a K&N, I fear that any difference felt is physiological.

I agree, it's psychological (assuming that's what you meant). A filter that is less restrictive won't alter the fuel/air ratio and the amount of work the engine has to do to pull air through the filter is trivial. It will make a difference at the top end of the engine's performance where it will make a couple of extra horsepower available (with a corresponding increase in fuel consumption).
I neglected the air filter on my bike for many years, it probably did about 80,000 miles in that time. There was no detectable change in mpg when I put the new one in.