roadrun_fr

what do you think about it ?
http://www.burniemorgan.com/firestorm/airfilter.html

modifying stock air filter by "cutting the sideways ridge off the air filter "

Any experience ? dyno results ?

What happens with a KN filter that don't have this "sideways ridge" ?

Has the airbox to be modified to gain something ? enlarge ? restrict ?
re-jetting required ?

jschmidt

It'll be interesting to hear theories. I don't think there is anything to gain there, at least on a stock bike.

RymerC

I remember reading that it was there to smooth out the airflow or something to that effect... reduce turbelence.
I cut the ridge on the filter part down, and really can't feel any difference.

VTRBeefa

I did this mod as soon as I got the bike so cant comment on before... however just picked it up after its 600k service and they have replaced it I believe, so I will do some tests..
A lot of the feedback i have read is the bike runs a little smoother and backfires/coughs less. I have to say i noticed my bike backfiring a bit more than usual today under brakes when giving it a blip. Will cut the lip off again and see if this cures it. : )


As for the questions about the air box, you do nothing, this is a very tiny mod and gives very tiny gain... but its cheap and easy.

As for the K&N question... Im not sure what you are actually asking. All the aftermarket filters do not have this ridge. You would have to ask then why does the standard one have it.... it could very well be that none of us are Honda design engineers so you would expect they know better than we do... however if it really was beneficial then you would think the aftermarket filters would also have it.

Will cut the lip off tomorrow and see how it goes..

roadrun_fr

I agree. I think honda engineers have designed this ridge for a good reason ... reduce intake noise ? resonance problems ?

I'm thinking about problems that some people noticed using a KN without jetting.
They loss power on the low and mid range.
But is it because of ridge loss or by the improve airflow or both ?

see http://www.dynamohumm.com/HONDA/VTR%201000/vtrk&n1.jpg
and
http://hirle.free.fr/courbes_VTR.html
to compare stock and KN dyno tests.
The last dyno shows lean mixture with KN and eratic torque.

Do you know the right air mixture for superhawk for low/mid/high rev band ?

In fact, I do have a KN filter.
Do i have to buy a new stock one or just modify my KN ?
I mean builind a ridge on it (without thinking about KN airflow improvement...) or adding a car paper filter above it or both ?

I have no need of power in high rev band but need power on low/mid range power and would enjoy smooth road ride at low speeds/rev...

Sorry about my poor english ...

VTRBeefa

The K&N (and any aftermarket filter) is designed to let more air flow in, which really helps as a motor starts reving and wanting to take in a larger volume of air.. As you increase the air intake you MUST increase the fuel delivery... otherwise you will get the problem you describe of lean running and eratic torque. For this reason K&N must be used with jet kit to allow more fuel and to re balance the air fuel mix which the standard needles cannot do.

If you prefer to have better low down torque for highway riding and cruising (not that it wont still go hard) get a standard Honda filter and install it... they are very cheap.
If you were to make a ridge for the K&N it would make very little difference to the torque of the bike and would be better off with Honda filter.

: )

roadrun_fr

yep ... do you really think that Honda filter is cheap ?

jschmidt

There are several possibilities
1. It could be there to route airflow to increase the radius of the flow turn over the velocity stacks. But if that were the case, it'd be better as a radiused shape.

2. It could be to stop the intake of moisture. but if that were the case there would be a drain system.

3. My vote goes for intake noise control. Is intake roar louder with it cut out?

inderocker

exactly. this ridge helps direct the airflow directly into the filter. cutting that ridge off would only cause an air flow disturbance. making more room for air to enter wll do nothing if it does not know where to go.

Mithrandir

I did that to mine and yes it makes a difference to throttle response and also got significantly better mileage - about 20Km a tank more in mostly high-speed freeway commuting. Much smoother. Combine this mod with the ignition advance and the bike becomes quite a nice monster.

macd218

I would have to agree. I did this also and the bike feels much smoother.
Less Back fire through carbs. I have slip-ons and its not jetted.

VTRBeefa

Ok after having ridden for a few days with the standard airfilter back in (and yes here in aus they are cheap !!! think it cost $22AUD)
I can confirm that the bike doesnt feel like it is responding as quick to throttle input, and feels like it is not pulling as good as it was with the modded air filter. The noise may be an issue, but i ride with ear plugs so its hard to tell.

As soon as I get a chance I shall be cutting the ridge off again as with my bike and pipes (Remus GP1's) there is a definite difference in cutting the ridge off.

Someone mentioned only taking it part off... Do the whole thing.

Here is my 2 cents: (and i discount noise straight off the bat, it has to be for airflow)

The ridge will create a low pressure on the downwind side of the ridge, thus causeing the air to get sucked down onto the airfilter... however (and this comes from building and flying gliders off slopes and cliffs for a number of years) directly behind that ridge, as air flows over it, will be a rotor or an area of almost still air that is rolling around on itself. Above this is a separation layer where the rest of the air will roll over the rotor and then onto the filter. (Test this for yourself by sweeping your hand through dirty or sandy water and you will see at the back of your hand, the particles follow your hand as they get stuck in the rotor)

As airspeed increases so will the length and size of the rotor hence the turbulence of the air in the airbox.
If we ignored this, then we could safely say that the air is drawn up and over the ridge, then down onto the filter feeding front cyl first... It may be that this turbulence is what the design brief was for the ridge. Given that the filter is the bottle neck in this process, the turbulence may help to distribute the air over a wider part of the filter for it to be drawn through.

Just some food for thought... whatever the case may be, it runs better without it

roadrun_fr

Thanx a lot for your answers !
In France, Honda genuine filter cost is about 53€ (about 75$ US), this filter is made with "gold" in Europe !
I've a KN, so I can't test easily the two stock filter configurations ...
I've stock pipes ans stock jetting.

I've bought a genuine filter and the bike is running better.
Smoother at 3000/4000 rpm, pulling harder at 5000/6000 rpm.
Idle more stable.
I've not yet tested (really) higher RPMs.
The air mixture seems to be richer. I can smell it at idle.
the fuel consumption may be increased.....?

The weather was warmer than usual (+30°C vs 20°C last week), so it is not a "perfect" comparaison ...

Do you think I will benefit "cutting' the ridge of this new air filter with my "stock" configuration ?

mikstr

I had cut the ridge on my VTR three years ago when it was totally stock (engine-wise) and it seemed to make a (positive) difference.

Storm

I just did this mod today. The bike has bafflectomy and cit the air filter ridge and removed the plastic piece with 2 Philips screws. The bike feels more responsive on the first snap of the throttle, but also backfire a lot more on deceleration. Don't mind the noise really.