Where is the "flapper"? - Wrist Twisters
 
Thread Tools Display Modes
post #1 of 14 Old 09-23-2006, 06:22 PM Thread Starter
Unbannable
 
Super Sneaky Steve's Avatar
 
Join Date: Sep 2006
Location: Michigan
Posts: 3,184
Rep Power: 1
 
Where is the "flapper"?

I opened up my air box and removed the airfilter looking for this flapper that eveyone says that I should remove. Didn't see it in there. So, just where is the little bugger and how do I remove it?


As a side note, not to waste space with another thread. Mother's Alluminum & Mag pollish is awsome! It works most metals, stainless 919 headers being one of them. It's raining and I have no friends so I decided to pollish up my bike. I thought my heat shileds and headers were nice as they were, but after some of this stuff and some elbow grease they look even better.

What the hell, I'll tack on another one. Has anyone tried cutting slots in the side pannel to let more air into the snorkle thingy? I heard about some guy making a velocity stack but can't remember wether it did anything, negative or positive.

Super Sneaky Steve is offline  
Sponsored Links
Advertisement
 
post #2 of 14 Old 09-23-2006, 06:33 PM
 
Join Date: Aug 2006
Posts: 126
Rep Power: 0
 

Awards Showcase
Veteran Extraordinary Ride 
Total Awards: 2

the flapper is on that "snorkle thingy", its round and the vaccum hose is connected to it on the outside of the intake

ad919 is offline  
post #3 of 14 Old 09-23-2006, 06:35 PM Thread Starter
Unbannable
 
Super Sneaky Steve's Avatar
 
Join Date: Sep 2006
Location: Michigan
Posts: 3,184
Rep Power: 1
 
Oh, I figured it was a sensor. I don't see how that could restrict airflow.

What do you do with it? Just pull the round metal thing off? What about the hose? Where do you connect it? Or would you just let it hang?

Super Sneaky Steve is offline  
post #4 of 14 Old 09-23-2006, 06:36 PM
 
Join Date: Aug 2006
Posts: 46
Rep Power: 0
 
The Air flapper is in the cover that you took off to get to the air filter. All you need to do is unplug the vacuum hose from the flapper valve and plug the hose off with a bolt. I unplugged mine and I couldn't tell any difference.

Mountain Road Madness is offline  
post #5 of 14 Old 09-23-2006, 06:38 PM Thread Starter
Unbannable
 
Super Sneaky Steve's Avatar
 
Join Date: Sep 2006
Location: Michigan
Posts: 3,184
Rep Power: 1
 
Thanks guys. I'll try it with my stock exhaust. Then I'll try it with my shiney new Staintune exhausts when the brown truck brings it to me.

I've heard people say it both ways. Some say it does nothing and others swear it adds 2hp. We'll see.

Super Sneaky Steve is offline  
post #6 of 14 Old 09-23-2006, 06:42 PM
Heavy Metal
 
ratdog's Avatar
 
Join Date: Jan 2006
Location: swamp in the wood
Posts: 4,304
Rep Power: 1
 

Awards Showcase
Donation Extraordinary Ride Donation Wrist Twisters Event Attendance 
Total Awards: 5

honda919rider's yahoo site

Honda919rider's Main Site

honda919rider did all kinds of stuff w/ the flapper/vstack

flapper mod info from 919.org


-------------snip from review section on project919 site------------
Honda919rider's Velocity Stack


A great mod pioneered on the 919 by Steve aka Honda919Rider.

Installation involved still more dremel work. You must sacrifice a stock air intake for the project. Optionally you can track down a used/salvage part. Fitting the actual velocity stack (same sized trumpet as used by small block chevy's) was a two step effort. Two steps because the first dremel effort didn't seat the stack flush with the rest of the box. This in turn prevented installation of the stock side cover. NOTE: make sure you mount the top of the stack flush with the air intake outer edge. The stack is secured in place with some silicone. All that remains is to plug the vacuum line.

First thing I noticed was the sound, I love the sound, especially when matched with Moriwakis or Gen I Satos. The bike growls down low and wails up top. Pinning the throttle to the stop rewards the pilot with the screaming Inline 4 sound that is only a dream to stock 9'r owners.

There is an actual effect on performance, low end throttle response seems more crisp, an instant and aggressive response, probably could benefit from some fine-tuning on the dyno. Folks considering this mod should probably consider purchasing a PC3, especially if mated with slip-ons.

On the Hooligan side, managing the balance point becomes a bit trickier, is actually easier to do with the stock airbox and vac line in place as you can be a bit lazy when managing the throttle, with the VStack in place, the bike is less forgiving at the balance point.

It would seem the open intake allows the engine to breathe more easily and low end performance improves. I will admit that the additional sound is intoxicating and my perceptions may be impaired, again the dyno will out.

definite poser points ;p

Admin: [ Edit | Delete ]
Added: July 18th 2004
Reviewer: ratdog
Score:
Hits: 1058
Language: english



[ Back to Reviews Index | Post Comment ]


Honda919rider's Velocity Stack
Posted by wockman on 2006-02-24 14:28:32
My Score:
Admin: [ Delete ]
--------------------------------------------------------------------------------


Has anyone else tried this mod?
When riding in the rain is there a problem with water getting in to the airbox?

ratdog is offline  
post #7 of 14 Old 09-23-2006, 06:45 PM
 
Join Date: Aug 2006
Posts: 126
Rep Power: 0
 

Awards Showcase
Veteran Extraordinary Ride 
Total Awards: 2

I did the mod (took around 5 mins) and I noticed an increase in intake noise but not anything in power but Im not the most experienced rider, Im sure some guys could tell a difference where the vavle opens and closes

ad919 is offline  
post #8 of 14 Old 09-23-2006, 07:00 PM Thread Starter
Unbannable
 
Super Sneaky Steve's Avatar
 
Join Date: Sep 2006
Location: Michigan
Posts: 3,184
Rep Power: 1
 
Hmm, I understand how to do it, but something doesn't make sense to me. If you are plugging the line, how does that increase airflow?

Wouldn't it also mess with the airflow sensor?

Super Sneaky Steve is offline  
post #9 of 14 Old 09-23-2006, 07:09 PM
Aquilifer
 
hooker_47's Avatar
 
Join Date: Jun 2006
Location: Fairbanks, AK
Posts: 1,250
Rep Power: 1
 

Awards Showcase
Donation Donation Veteran 
Total Awards: 3

I think the idea was the flapper works backwards of how it should. If I remember right, it cuts down airflow at higher RPM's to lessen noise. It's something Honda did to pass EPA noise level tests. I noticed a smoother acceleration and power band when I disconnected it. Instead of a power take-off at about 4500, it accelerates smoothly now.

Some of the more knowledgeable people on here can probably tell you more. Also, check out LDH's page (919.org). He explains it there too.

-Joe
hooker_47 is offline  
post #10 of 14 Old 09-23-2006, 07:33 PM
Corner speed sets u free
 
streakin919's Avatar
 
Join Date: Sep 2006
Location: Pacific NW
Posts: 1,115
Rep Power: 1
 
Garage

Awards Showcase
Trackday Recognition Donation Veteran 
Total Awards: 3

you'll notice the difference at the track for sure... like hooker says, accel is smoother that's about all you get... i don't think you gain any horses from it.

streakin919 is offline  
post #11 of 14 Old 09-23-2006, 07:39 PM
Milites Gregarius
 
Join Date: Aug 2006
Location: Shreveport, LA
Posts: 169
Rep Power: 1
 
Make sure to plug the line with an old srew or something, the dowel pins from cheap bookshelfs work perfectly.

mrjason is offline  
post #12 of 14 Old 09-23-2006, 08:29 PM
Tirone
 
Join Date: May 2006
Location: up north
Posts: 99
Rep Power: 1
 
Honda did it for noise emissions as on the RC51. I do know that on a 100hp bike you're hard pressed to feel one or two extra ponies with the butt dyno.

RxRC is offline  
post #13 of 14 Old 09-24-2006, 12:31 AM
Sweepuk
Guest
 
Posts: n/a
This has just been discussed at length at the hornets nest as I asked if anyone felt it was better leaving it as standard as I found little difference.

The pipe that you plug is not plugging the air supply to the engine, it is plugging the air to the valve that actuates the flapper door in the entrance to the airbox. This is not shut at high rpms but at lower rpms (up to just over 5000 revs) this is done by Honda to reduce intake noise to pass regulations for noise polution.

I am running with the mod done again - trying to see if it does make a difference to me in my riding of the bike - the jury is out - still not sure I can feel much benefit.

post #14 of 14 Old 09-24-2006, 12:33 AM
Sweepuk
Guest
 
Posts: n/a
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Wrist Twisters forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome