K&N Air Filters
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The O2 sensor in the exhaust and the ECM make sure your air to fuel ratio (AFR, or stoichiometric mixture) is maintained at the EPA mandated 14.7 to 1 ratio with all fuel blends, and in all conditions when the fuel system is operating in the 'closed loop' configuration.
This is pretty much all the time ....... except when at idle or wide open throttle (WOT).
At these times you are running 'open loop' and the fuel mixture is controlled by a programmed map in the ECM that looks at throttle position and engine RPM and controls the AFR based on preprogrammed parameters ..... "the map", which allow it to go a bit more rich and prevent a situation that might cause the engine to overheat, as the mandated 14.7:1 is a pretty lean mixture (that while forcing the engine to completely burn the fuel and not pollute) is the main reason for hotter running engines.
So ..... when you change the exhaust or intake for better breathing, the mileage will only change as a result of the change that can be effected at WOT or idle (in open loop) because the AFR will not change at all when in closed loop .... where the lions share of the fuel is consumed.
IOW: Although it 'can' change mileage and performance, it will only be 'modestly' noticed if you do a lot of drag racing.
Aftermarket ECM add-ons allow you to intercept the the O2 sensor's signal and provide an offset based on a map that you can modify with a program running on a PC, 'or' is automatically modified in some aftermarket models (like DynoJet's auto-tune) that tricks the ECM into running different AFR based on maps you modify to accomplish an AFR that is performance based as opposed to just pollution control.
Some of these systems will allow you to preprogram a number of maps for different riding conditions (like richer for a parade mode to prevent overheating, lean for hiway cruising or a performance mix and etc.).
Unfortunately (or fortunately is you are on the side of the EPA) nobody makes a plug and play system (like DynoJet) for the GL1800, so we are stuck with the mandated 14.7:1 and the fixed performance, heat and arguably lessened engine life as a result of running such a lean mixture.
In some cases this is a good thing because to get better mileage you have to run an even leaner AFR ...... and that would not be good.
To get more power the old adage of "cubic inches make HP" has never been more correct.
No longer can you do a plug chop and tweak the intake and exhaust to get more power or mileage. It just doesn't work when the the closed loop system rats you out every time, and automatically makes the adjustments to force you to 14.7:1.
This is pretty much all the time ....... except when at idle or wide open throttle (WOT).
At these times you are running 'open loop' and the fuel mixture is controlled by a programmed map in the ECM that looks at throttle position and engine RPM and controls the AFR based on preprogrammed parameters ..... "the map", which allow it to go a bit more rich and prevent a situation that might cause the engine to overheat, as the mandated 14.7:1 is a pretty lean mixture (that while forcing the engine to completely burn the fuel and not pollute) is the main reason for hotter running engines.
So ..... when you change the exhaust or intake for better breathing, the mileage will only change as a result of the change that can be effected at WOT or idle (in open loop) because the AFR will not change at all when in closed loop .... where the lions share of the fuel is consumed.
IOW: Although it 'can' change mileage and performance, it will only be 'modestly' noticed if you do a lot of drag racing.
Aftermarket ECM add-ons allow you to intercept the the O2 sensor's signal and provide an offset based on a map that you can modify with a program running on a PC, 'or' is automatically modified in some aftermarket models (like DynoJet's auto-tune) that tricks the ECM into running different AFR based on maps you modify to accomplish an AFR that is performance based as opposed to just pollution control.
Some of these systems will allow you to preprogram a number of maps for different riding conditions (like richer for a parade mode to prevent overheating, lean for hiway cruising or a performance mix and etc.).
Unfortunately (or fortunately is you are on the side of the EPA) nobody makes a plug and play system (like DynoJet) for the GL1800, so we are stuck with the mandated 14.7:1 and the fixed performance, heat and arguably lessened engine life as a result of running such a lean mixture.
In some cases this is a good thing because to get better mileage you have to run an even leaner AFR ...... and that would not be good.
To get more power the old adage of "cubic inches make HP" has never been more correct.
No longer can you do a plug chop and tweak the intake and exhaust to get more power or mileage. It just doesn't work when the the closed loop system rats you out every time, and automatically makes the adjustments to force you to 14.7:1.
Why do you install K&N filters on your motorcycles?
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250 Posts
If more 'dirt' is passed, it is as easily consumed as any passed by the stock filter.
IMO it comes down to whether you will leave the K&N in significantly longer between services than the OEM. Whether you will have the bike long enough to make it 'cheaper' than buying the alternative paper filters is hardly an issue if you've added a single farkle.
IMO it comes down to whether you will leave the K&N in significantly longer between services than the OEM. Whether you will have the bike long enough to make it 'cheaper' than buying the alternative paper filters is hardly an issue if you've added a single farkle.
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3,537 Posts
In my humble opinion from fooling with Race Cars for many years, they ain't worth the money.
A quality stock filter will serve all your needs.
They Do Not increase Performance.
All any air filter does, is filter incoming air.
A quality stock filter will serve all your needs.
They Do Not increase Performance.
All any air filter does, is filter incoming air.
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82 Posts
Where is your proof ?
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1,853 Posts
I get OEM filters from my dealer for $20. change every 25k. I don't have to buy a cleaning kit for it and get all grungy cleaning a filter and oiling it up again. OEM is much easier
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3,716 Posts
i recently put one in and there no difference in power or fuel economy same as the stock filter IMO the stock one i used to change every 30K or so and was relatively clean i am thinking i will recharge the K&N every 40 to 50 K and see how dirty it is and check out the air box for any excessive dirt or oil if normal i stick with the K&N
Board member digger has one in hes 1800 for a long time maybe he can comment i think he took some pictures of the filter at 50k
Cheers :thumbup:
Board member digger has one in hes 1800 for a long time maybe he can comment i think he took some pictures of the filter at 50k
Cheers :thumbup:
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1,124 Posts
I used to own a DynoJet chassis dyno, and sold K&N Filters. I know that on most vehicles (I only tested cars) the K&N did make power, from 1-2 hp to 6-8. ON one dirt track car, we made almost 10 hp over a clean stock filter. But this is ONLY at wide open throttle. At anything less than that, you don't flow enough air to tax a good, reasonably clean stock filter.
As for MPG, I don't agree with K&N, they do NOT make any more MPG, because you care about that at very little throttle opening, and as stated above, not enough air is flowing to use the K&N's flow advantage.
I Have also done white glove tests on bikes and cars that I have put K&N filters on, and never found any dirt past the filter. I have also done oil analysis. Any air filter that lets dirt through in any significant amount will show up immediately in oil analysis as increased silicon (basically sand from the highway/dirt etc) will be easy to spot. The only time I found the slicon number going up, I was able to catch that my aftermarket cone K&N filter had been rubbing up against a bracket, not the filters fault, MY fault. A hole had rubbed in (very small) and the silicon numbers went way up. A bit of Silicone sealant solved the problem, I still run that filter years later!
If you don't care about that maybe 1-2 hp at WOT, and you don't plan on keeping the vehicle for 100,000 miles or so, then the stock filter will probably be the way to go. K&N is a good filter, has one advantage, and no real disadvantage other than cost, and cleaning it isn't any big deal, the kit is about $10 and will clean the filter 5-10 times.
As for MPG, I don't agree with K&N, they do NOT make any more MPG, because you care about that at very little throttle opening, and as stated above, not enough air is flowing to use the K&N's flow advantage.
I Have also done white glove tests on bikes and cars that I have put K&N filters on, and never found any dirt past the filter. I have also done oil analysis. Any air filter that lets dirt through in any significant amount will show up immediately in oil analysis as increased silicon (basically sand from the highway/dirt etc) will be easy to spot. The only time I found the slicon number going up, I was able to catch that my aftermarket cone K&N filter had been rubbing up against a bracket, not the filters fault, MY fault. A hole had rubbed in (very small) and the silicon numbers went way up. A bit of Silicone sealant solved the problem, I still run that filter years later!
If you don't care about that maybe 1-2 hp at WOT, and you don't plan on keeping the vehicle for 100,000 miles or so, then the stock filter will probably be the way to go. K&N is a good filter, has one advantage, and no real disadvantage other than cost, and cleaning it isn't any big deal, the kit is about $10 and will clean the filter 5-10 times.
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