Flapper mod? - Wrist Twisters
 
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post #1 of 17 Old 09-08-2006, 06:34 PM Thread Starter
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Flapper mod?

Does this really increase performance? By the way I'm talking about the flapper mod on 919.org.

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post #2 of 17 Old 09-08-2006, 07:18 PM
 
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i noticed a little more midrange punchiness. hard to say without a dyno whether its in my head or not though.


I did have a verifiable change in fuel mileage, for the better ... I ran three tanks full before I did the flapper mod and three tanks after, using the bike the same way and about the same temperature, not super scientific but I figured with three tanks full It would average pretty close.

after all said and done 18 m/tank more after the mod.

like i said not the most scientific experiment but in my mind its pretty solid.

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post #3 of 17 Old 09-08-2006, 08:42 PM Thread Starter
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Is there any difference in the sound the bike produces?

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post #4 of 17 Old 09-08-2006, 08:45 PM
 
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noticed a little throaty howl commin from the air box... but that also could be the k+n filter

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post #5 of 17 Old 09-08-2006, 08:49 PM Thread Starter
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Thanks for the quick replies!

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post #6 of 17 Old 09-08-2006, 09:07 PM
 
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when i did it on my bike, it seemed to decrease that little bit of hesitation of at low idle to full-throttle whacks. however, it did not make as much of a difference (perceived) as the power commander with the accelerator pump mod.

Btw, nice name.

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post #7 of 17 Old 09-08-2006, 09:14 PM
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Btw, nice name.
Ha! That was funny.

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post #8 of 17 Old 09-08-2006, 09:46 PM
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Ha! That was funny.
what he said...

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post #9 of 17 Old 09-09-2006, 07:01 PM Thread Starter
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Today I had time to take a look at the flapper door on the air inlet of the airbox. At first glance it looked like a set up you would see on a car(dual intake runners), I then took it for a ride and using my hand I was able to feel the way it worked. The valve closes the door when ever the throttle is pulled half way back under load. This is very confusing to me, being a car mechanic for audi the way this should work is as follows, when the vehicle is at idle the door to the large straight tube should be shut improving low end torgue and then at wide open throttle(or a predetermined rpm) the valve should open giving the air a quicker path to the engine for high end horse power. So in my opinion this valve does nothing but hender performance, if it worked just opposite of the way it does I could very well see it improving performance, but it doesn't so I say disconnect it.

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post #10 of 17 Old 09-09-2006, 07:08 PM
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I thought the flapper was originally put there to reduce noise emissions or something, some damn test that Honda had to pass. I disconnected mine and never even thought about hooking it back up...

-Joe
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post #11 of 17 Old 09-09-2006, 07:25 PM Thread Starter
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That may be the case, but I can't see it make that much of a difference in noise when the epa doesn't use wide open throttle for their tests.

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post #12 of 17 Old 09-09-2006, 07:26 PM
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So, what's the consensus on the flapper mod? It's easy enough to do. It increases the noise levels. But are the benefits worth the increase in dB's?

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post #13 of 17 Old 09-09-2006, 07:35 PM Thread Starter
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It doesn't increase the noise much at all and about the gains, you just can't be sure there are any with out a dyno.

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post #14 of 17 Old 09-09-2006, 10:25 PM
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Ive gone back and forth with the flapper mod, and finally have had it off for quite a while,, almost forgot about it..

If you play with it and ride enough, (everyday here) you will notice more simply,, a smoother power curve, or roll-on power.... the stock noticeable lurches and dead-pans in power, (on a very steady roll on acceleration) will even out much more smoothly with the flapper removed, regardless how or why it isin there, it makes sense that something that doesnt change in the intake at different RPM's would equal to a more steady curve... as far as power gains or losses, it shouldn't really make any change, as at WOT the flapper is open, and even down low.. its more in the midrange, it just might make a loss in power at certain power bands... but not that it's loosing power, but it is spread out more evenly, which in my opinion is a more desireable thing...
Of course, if you've ever ridden a V-max, when that v boost thing kicks in, its kinda a cool feeling but that is a large dump of power...

I still haven't heard anything about an "official" reason this thing is in the bikes, or the RC, Lord Duck has had by far the best info on this that i've seen...

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post #15 of 17 Old 09-09-2006, 11:34 PM Thread Starter
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Quote:
Originally Posted by Caleb_I View Post
Ive gone back and forth with the flapper mod, and finally have had it off for quite a while,, almost forgot about it..

If you play with it and ride enough, (everyday here) you will notice more simply,, a smoother power curve, or roll-on power.... the stock noticeable lurches and dead-pans in power, (on a very steady roll on acceleration) will even out much more smoothly with the flapper removed, regardless how or why it isin there, it makes sense that something that doesnt change in the intake at different RPM's would equal to a more steady curve... as far as power gains or losses, it shouldn't really make any change, as at WOT the flapper is open, and even down low.. its more in the midrange, it just might make a loss in power at certain power bands... but not that it's loosing power, but it is spread out more evenly, which in my opinion is a more desireable thing...
Of course, if you've ever ridden a V-max, when that v boost thing kicks in, its kinda a cool feeling but that is a large dump of power...

I still haven't heard anything about an "official" reason this thing is in the bikes, or the RC, Lord Duck has had by far the best info on this that i've seen...

The door is actually closed during WOT.

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post #16 of 17 Old 09-10-2006, 03:36 AM
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Instead of going through a long drawn out explanation, read this recent thread posted on the Hornet's nest. LDH sums it up perfectly.
http://p196.ezboard.com/fhornetsnest...cID=3403.topic

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post #17 of 17 Old 09-10-2006, 04:41 AM
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Hmm, yea, thats a good thread over there...

I did do a rather un-scientific approach, using some spiderwire, a small flexible pvc sleeve, and attatched it to the flap, and drove around,, now,, while trying to judge, with one hand on the bike, and one holding the sleeve, and watching 2 pieces of tape move(for marking purposes) It is not closed during wot, as far as closing upon launching,, perhaps, that was the time i was clinging to the bike, one handed... LOL but it did close shortly there after, as i mentioned above, i don't have any rpm numbers to say,, but,, it went like...

open,,,, brrrrrr closed.... brrrrrrrrrrrr open.....

How's that for a in field test Hahaaaa

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