[ConqSoft]

Submitted by: abtech

We ran the following tests regarding air filters on a stock 929 with OEM exhaust, Hindle bolt on and Hindle full system:

OEM filter 3 runs:

OEM Exhaust best run: 121.5
Hindle bolt on best run: 124.0
Hindle full system best run: 133.5

K&N 929 replacement filter:

OEM Exhaust best run: 119.0
Hindle bolt on best run: 121.0
Hindle full system best run: 129.5

"Whacked" filter (all paper removed, both screens remained)

OEM Exhaust best run: 124.5
Hindle bolt on best run: 127.5
Hindle full system best run: 137.0

These test were run on 108 Octane Sunoco "pump" race gas on a DJ 250 and were made without any third party fuel management system (i.e. PC111 etc.) The test site is 530 ft above sea level and all readings are SAE sea level temp and pressure corrected from "actual" 80 degrees ambient temp and 74% relative humidity.

The same set of tests run on Torco Stealth 14 followed almost identical curves, but yielded an average of 3 additional HP except for the full system with the "modified" OEM filter which produced 144 to 146 HP in 12 consecutive runs.

Pair system was removed (and sealed) while the flapper was IN during all tests.

[Leistung Elektr]

Hi, i´m new on the forum. I have a 919 1996 with a few modifications..ported head, more compression...and i have a fuel injector throttle bodies with a (ECU that i sell..now only for drag cars...soon for bikes...) to add so i can play with fuel. I had to rebuilt the motor because a crankshaf bearing problem (twice).

Mi question is that you change fuel curves o jets in diferent test or fuel remains original for all?

Thanks

Miky......from Argentina

[abtech]

Originally Posted by Leistung Elektr

Hi, i´m new on the forum. I have a 919 1996 with a few modifications..ported head, more compression...and i have a fuel injector throttle bodies with a (ECU that i sell..now only for drag cars...soon for bikes...) to add so i can play with fuel. I had to rebuilt the motor because a crankshaf bearing problem (twice).

Mi question is that you change fuel curves o jets in diferent test or fuel remains original for all?

Thanks

Miky......from Argentina

Miky. At the time of the testing documented in this article, no one had any mapping device available for the new (at the time) 929 engine. DynoJet did make their PowerCommander series available by late June of 2000, but all of this testing was done prior to the beginning of the racing season (March, 2000).

Subsequent testing with both the 929 and 954 has shown this information holds up very well even after hours of custom fuel mapping time on a DynoJet 250 with their Tuning Link software and on a water brake engine only dyno that was performed in late 2003. We also found that with a totally modified airbox (all internals removed, fire screen only) and VP Racing's U4 race fuel, the engine picked up an additional 6 HP over 93 octane unleaded pump gas. After mapping, we saw nearly 10 additional HP with the U4 on the 954 with the modified airbox.

These gains were entirely due to the fuel, as everything else stayed the same throughout the testing.

[929RRider]

I'd like to see someone dyno a Pipercross filter.

[johnx144]

some interesting figures there. i'd heard k&n were'nt that good as people originally thought..

[Twincam]

Originally Posted by johnx144

some interesting figures there. i'd heard k&n were'nt that good as people originally thought..

Regarding the 954RR, K&N filters actually restrict air flow therefore reducing power... On other bikes they may increase air flow.

[denzee]

Great stuff! However I do worry about everyone yanking out their filter paper in search of a few more ponies.

Also when you spray the oil on the K&N after a bath, one would think it would reduce flow if too much oil was sprayed on. Likewise more flow with none or very liitle oil. Comments please.

[Twincam]

Originally Posted by denzee

Great stuff! However I do worry about everyone yanking out their filter paper in search of a few more ponies.

Also when you spray the oil on the K&N after a bath, one would think it would reduce flow if too much oil was sprayed on. Likewise more flow with none or very liitle oil. Comments please.

Ive always wondered what the oil actually does? Oil would attract dust/dirt particles - so wouldn't that be what the filter should be doing?

[denzee]

Originally Posted by Twincam

Ive always wondered what the oil actually does? Oil would attract dust/dirt particles - so wouldn't that be what the filter should be doing?

That's exactly what the filter oil does Twin, however it impeads airflow somewhat while doing it. Question is, how much?

[Twincam]

But why would a state of the art filter need oil to do what its supposed to do already? You also can't use petrol on the filters either (K&N's as it somehow spoils them...)

Hmmm, we need someone with a 954 and a few filters to test it out.

[denzee]

Originally Posted by Twincam

But why would a state of the art filter need oil to do what its supposed to do already? You also can't use petrol on the filters either (K&N's as it somehow spoils them...)

Hmmm, we need someone with a 954 and a few filters to test it out.

It's all because they are wasable and reusable. They only contain a fine steel mesh that works well but can't filter air like a paper media. When the special filter oil is sprayed on, it is now able to filter out smaller microns of dirt much like paper media.

[Twincam]

Originally Posted by denzee

It's all because they are wasable and reusable. They only contain a fine steel mesh that works well but can't filter air like a paper media. When the special filter oil is sprayed on, it is now able to filter out smaller microns of dirt much like paper media.

Thanks for clearing that up for me

I wonder if it would restrict air flow if the users would not add the oil (when compared to OEM)

[denzee]

Originally Posted by Twincam

Thanks for clearing that up for me

I wonder if it would restrict air flow if the users would not add the oil (when compared to OEM)

My guess is that it would flow better than OEM but would be unable to filter damaging dirt out of the engine. I ran a cb750 with only velocity stacks for a time when I was 17 and literally destroyed the engine. I first started getting a lot of blowby out of the crankcase and when I tore it down, the piston rings fell off in little pieces about a 1/4"long. What a mess. Huge lesson learned. One of many lessons learned at that time.

[FireBlue]

Awesome effort with the comparisons mate!

I assume it is inadvisable to run a whacked filter on the open road?

[bladeracer]

Originally Posted by FireBlue

Awesome effort with the comparisons mate!

I assume it is inadvisable to run a whacked filter on the open road?

It is not advised to run a "whacked" filter at all - not even on the racetrack. Stick with OEM if you want your engine to last a while or BMC if you really must have a reusable filter.

[FireBlue]

CHeers man, is a BMC better than oem or would it decrease power like the K&N does?

[bladeracer]

Originally Posted by FireBlue

CHeers man, is a BMC better than oem or would it decrease power like the K&N does?

If by better you mean "does it let more air and debris through" then yes it's better. Personally I prefer a better filter and I'll make up the marginal horsepower deficit with skill :-)

[madmatt01]

I've always been a believer in K&N filters for all of my bikes, cars, trucks, etc. This thread has opened my eyes. I'll have to rethink things a little. I wonder why I've typically experienced better fuel economy when running the k&n filter than stock or paper filters when they are actually not flowing as much air. I'd think (I know, I know, that's dangerous) that the decreased power would result in a heavier foot (or wrist) causing me to lose fuel mileage. Any ideas or suggestions? I'm not familiar with the BMC filters, how do they rate for longevity and price?
Thanks in advance

[bladeracer]

Originally Posted by madmatt01

I've always been a believer in K&N filters for all of my bikes, cars, trucks, etc. This thread has opened my eyes. I'll have to rethink things a little. I wonder why I've typically experienced better fuel economy when running the k&n filter than stock or paper filters when they are actually not flowing as much air. I'd think (I know, I know, that's dangerous) that the decreased power would result in a heavier foot (or wrist) causing me to lose fuel mileage. Any ideas or suggestions? I'm not familiar with the BMC filters, how do they rate for longevity and price?
Thanks in advance

If they flow less air, than the carbs are also flowing less fuel since air velocity is what determines how much fuel is siphoned from the float bowls.

[SoliceDreamer]

i thought K&N slugged down the engine...from what i've read on here...are the results because the exhaust?

[madmatt01]

BladeRacer,
Wouldn't a decrease in air/fuel flow resulting in less power then lead me to be harder on the throttle, thus worsening fuel economy? The fuel economy is always what has lead me to believe that the K&N was flowing air more freely.

[bladeracer]

Originally Posted by madmatt01

BladeRacer,
Wouldn't a decrease in air/fuel flow resulting in less power then lead me to be harder on the throttle, thus worsening fuel economy? The fuel economy is always what has lead me to believe that the K&N was flowing air more freely.

Depends on how you use the throttle.
If you're using full throttle everywhere then I guess it might make a difference. Otherwise, probably not.
If the filter were flowing more air I'd expect the carbs to suck more fuel.
The carbs are simply a stream of air. The piston goes down the cylinder creating vacuum and drawing air through the carb throat.
The air flows across the top of the jet creating vacuum and causing fuel to be sucked up out of the jet in proportion to that air flow. Close the throttle plate or reduce the RPM and you will suck less air and less fuel.
The float level keeps the fuel at the same height so the amount of fuel being siphoned doesn't decrease as the fuel level drops.
Twenty years ago everybody believed K&N's were better filters but the advent of cheaper dynos has proved different, although I'm sure there are still older engines that are stifled enough that a K&N could be an improvement.
Personally I doubt very many riders derive any benefit from a more open filter anyway and certainly not enough to warrent the increased engine wear. Stick with OEM.

[madmatt01]

I certainly agree with your last comment about benefit. I think that most "benefit" from mods is perceived because the vast majority of bikes aren't ridden anywhere near their potential, making it a moot point. I'm just happy to know that on this bike I can save the extra cash and just go with a normal filter.

[wild_r1]

good topic! found similar results with my 00 R1. with a D&D exhaust stage 2 jetting 150 mans. k&n filter yielded an avg of 136 to 138 on the dyno, i swapped out the k&n for a stock filter and saw a 4 to 5 hp in increase and a cleaner fuel air curve with the bike, same dyno same day. bike pulled 142 avg with a best of 144. for me this was a huge eye opener! now both my bikes ( 929, R1 ) run stock filters. i still believe cold air kits work well, my truck seems to have benifited from it. i have also seen individual filters give great results on some carbed bikes. but we wont get into the tuning times with those set ups! but stock box means stock filter.

Rubber Side Down!!!

[tarenson]

How about DNA filters? Are they like a K & N?