I finally stopped riding my 919 for 10 minutes to do the flapper mod today. I looked at some threads on WT and followed the instructions on 919.org - no problems. I have a question about the flapper: what RPM is it supposed to close at? Before I disconnected the vacuum line, I started up the bike and tried to make the flapper door engage while I was looking at it, and I couldn't get it to move. Anyway, I disconnected the vacuum line and plugged it with a screw.
So, has anyone else revved the motor (before the flapper mod was performed) and checked what RPM the door opens and closes at? I thought I would be able to make the door move by revving the engine, but it wouldn't do anything. I'm not concerned because my flapper isn't working (I was disconnecting it, obviously), but why didn't it work the way I thought it would?
I'm concerned that the other end of the vacuum line is not connected or something.
I never check my self, but it is closed below 4500 rpm and open above. Doing the flapper mod allows better airflow and I think a more linear torque curve.
I got a screw protector, which is a small cap, and took the hose off there. I already had my tank lifted doing the pair block off plates. The bike definately roars now with the flapper disabled
I did the flapper mod a couple of weeks ago because I noticed a weird surging when cruising between 4500 and 5000 rpm. I remembered that I had read that this was the range where the flapper valve opened. Problem cured.
Before I disconnected the vacuum line, I started up the bike and tried to make the flapper door engage while I was looking at it, and I couldn't get it to move.
I did the same thing and got the same result... nothing. I am just guessing but maybe the vacuum isnt very strong unless the motor is under a load, therefor just reving it in neutral dosnt create enough suction to close the flap. Then again maybe thats not why, I dont know, just guessing. Like you said, it dosnt matter now because it is disconnected anyway.
It's a load thing. I was real curious about it as well, so I road it with the side cover off and sure enough, that flapper started a flapping.
If you do this yourself, please be very careful. It's not easy (or safe) trying to accelerate hard to the propper RPM while trying to look at your flapper.
The difference in function is subtle between hooked up and blocked off, but it sure sounds alot cooler. Now I ride around town thinking, hey everybody look at me, I sound cool!
in the attached pic, is the circled area the proper hose to disconnect? thanks... seems the instructions on 919.org aren't detailed enough for me i've definitely noticed the power surge and am trying to smooth things out
My question is, can the device at the other end of that be removed, and the hose back to the junction? Anyone thats done the mod and had their tank up high enough should know what I am talking about. I'm sure I could cram a resistor in there and fool the ECU into thinking it's opening the solenoid, but I have no idea of how to figure out the value of the resistor I would need, if I even need one at all.
no need to take off what is on the other side of that. Also don't unplug the electric cable to it either. I took the hose off and put a 1/8" plug over the outlet. The computer still thinks that it is opening and closing.
THe tank doesn't need to come up that far, just as far as the cable allows you. i put a piece of wood perpendicular across the frame to hold the tank up. I slipped the hose off with a pair of pliers, and slid the plug on.
So just so I understand , The bike sounds different with this mod done ,now is that at all rpms or just over 4500 when the flapper engages if you still had it hooked up?
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it affects under 4500. As it is closed below 4500 stock and open above. I don't think it makes the bike sound different other than the intake noise. What I mostly noticed is that the power is constant, linear torque curve, no jump in power all the sudden(as when it would open up normally).
did the mod today and it took 10minutes exactly. put on about 150 miles of all types of roads. nothing technical unfortunately but i did notice that the girl was a lot less jerky and way smoother than previous. 1 question though do i have to cap the nipple where the hose was connected or is it ok to keep uncovered? or did i do it wrong and am completely fos?
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No need to cap it unless your concerned about a bug crawling into the valve. I no intent of ever using the flapper again, and am curious if its possible to remove the valve and flapper.
i did the mod a couple of weeks ago, i left the vacum line and valve thing in place.
I just did a bit of careful prying with 2 screwdrivers and removed
the flapper itself.
No need to cap it unless your concerned about a bug crawling into the valve. I no intent of ever using the flapper again, and am curious if its possible to remove the valve and flapper.
I unscrewed the Plenim, removed the vacuum pump and used some chrome duct tape to seal the hole it left leaving a smooth flowing tunnel........I believe someone could design a better system to increase airflow to the filter without ramming rain and bugs into it as well.
after 4000 miles i decided to try the flapper mod....with the bike off the valve was open...when i started it it stayed open...should it be closed when the bike is off ? thanks for any info.....if its not correct what would keep it open...it moves freely my hand
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dont need a bike to ride the fast lane
after 4000 miles i decided to try the flapper mod....with the bike off the valve was open...when i started it it stayed open...should it be closed when the bike is off ? thanks for any info.....if its not correct what would keep it open...it moves freely my hand
Quote:
Originally Posted by cmurphy84
Since the flapper is vacuum operated, wouldn't it only close while decelerating?
I"ll have to confirm on mine, but i think mine is spring loaded open.
The manual says 5200 rpm or higher the flapper is open, 5200 rpm or lower the flapper is closed.
I did the the flapper when I got my 07 919, and went back a month later, I prefer the surge in power, sort of felt like a 2 strokes powerband. I didnt notice any increase in power, just sounded a touch better. It feels like it closes around the 5-5k rev range.
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I come from the land Down Under, Where the women blow and the men thunder!!
I did the the flapper when I got my 07 919, and went back a month later, I prefer the surge in power, sort of felt like a 2 strokes powerband. I didnt notice any increase in power, just sounded a touch better. It feels like it closes around the 5-5k rev range.
thats what im starting to think ....it closes not opens like everyone thinks in the higher rpm
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dont need a bike to ride the fast lane
If it would close at higher rpm then the engine would get less air and can't create more power (or the feeling of).
you can do a test:
...i worded that way to get a response ..asked a few times..seems to be a big secret ...the valve is open when starting up and..in neutral reving up motor it stays open...is that normal..
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dont need a bike to ride the fast lane
...i worded that way to get a response ..asked a few times..seems to be a big secret ...the valve is open when starting up and..in neutral reving up motor it stays open...is that normal..
don't know, but i would say so. many have reported before testing revving the bike watching with no load.
I'd also say yours functions correctly and why they state disconnect the neutral wire and then it should function. What happens when you do that?
don't know, but i would say so. many have reported before testing revving the bike watching with no load.
I'd also say yours functions correctly and why they state disconnect the neutral wire and then it should function. What happens when you do that?
thanks for that info...i have not touched neutral wire....have had it in gear clutch in and reved it up stays same position..suppose i could take it for a ride woth side panel off and take a look at the door..that would answer all my questions....i do know holding door closed and reving motor it bogs
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dont need a bike to ride the fast lane
Either my earplugs weren't seating as well as usual, or the flapper mod has an increased in intake howl. If it's louder, it must be open. Gas mileage was just over 50mpg for two tankfuls today...that's not worse than before, (it's actually better), so at least I think it didn't hurt fuel efficiency. Two tankfuls isn't enough to say it helped (even I usually only get 40-something). I like it.
just took the bike for a ride with side cover off....flapper is not working...i remember 4 months back with a snap of the throttle the front would head towards 12 oclock now it dont ..getting exhaust bracket done at same time
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dont need a bike to ride the fast lane
I'm under the idea it closed to stop the intake howl to meet Euro 3 noise rules......
well mine dont work like manual says...honda wont let the shop work on it because they say it not a drivability issue..had to call costumer service and find out why they refuse to fix it...im starting to think most dont work or dont work in the way the manual says...thinks theres a problem that they dont want to let out......mine stays open with neutral wire unpluged....with some high rpm in neutral it starts to half way close ..with a load it might close all the way.....dont know im trying to find out...they may have ecu problem with just the valve and dont want to let it out
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dont need a bike to ride the fast lane
update...honda just got back to me from california ..they said the procedure in the manual is not correct on the operation of the flapper valve....so im going to plug the line and see if i can feel or hear a difference ..like i said it did try to close with high rpm .. maybe under a load it fully closes then opens when vacuum is lost.......he did mention epa and noise,,,,,seems to me if what they say is true ,on a hard pull the valve will close knocking down the noise then reopen soon after......i hate people
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dont need a bike to ride the fast lane
so finally i did the flapper mod..after going threw honda for a few months and the tech line in california..because mine did not work like manual said it should.....there right the flapper does not work like the manual says....bike has more balls at 5000 rpm and above going buy wheel lift off the ground and the clean strong pull... flapper starts closing a bit under under a hard load..could be at any rpm mostly in the low mid rpm range...some talk a good game ..i found out for sure.....if not convinced tape your flapper closed and take it for a spin....im sure there will be no response from in crowd the know it all.s..but im sure some want the straight facts...thanks for the rep point who ever you are
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dont need a bike to ride the fast lane
I didn't notice enough of a difference after I did the mod to really even rave about it. The bike ran smooth before, and ran just as smooth after. I've also cut out the exhaust baffles, which may have had some bearing on it...
The flapper door only closes when there is a SUFFICIENT load on the motor to create enough vacuum on the hose AND the solenoid is told by the ECU to close the flapper door! It will never work just by revving the bike up etc...
I've dyno verified these results once already and posted them on the Motorush forum. One of the British magazines did the same back in 2002 what the fvck is everyone's problem?!?!
If flapper valves really worked as they are claimed then ALL Factory team racebikes in the professional race paddocks would have flapper valves installed on them, but they don't!!!!!!!!!!!
It does not take a rocket scientist to figure out why that is
It does not take a rocket scientist to figure out why that is
Well then take some tylenol or something, I did the mod, and didn't notice a change. Ok, maybe you have a dyno sheet saying it made more power and I don't, but the bike between my legs feels the same as it did before the mod. So, you can take your dyno sheets, wad them into a neat little ball and shove them right up your . Get over yourself and realize that everyone's bike isn't the same.
Actually they are the same when we are talking about positive or negative influences on the induction system what works for one bike on the assembly line will work for all of them.
I've forgotten more about tuning these bikes than you are ever going to know so
Most riders don't feel anything because they lack the experience to know what to look or feel for. Just the same the placebo effect is in place as well which is more than a proven phenomena where riders who just spent money on some sort of gimmicky performance mod and will openly attest that they now feel the benefits of that mod when in truth many times they have lost horsepower.
Most riders don't feel anything because they lack the experience to know what to look or feel for. Just the same the placebo effect is in place as well which is more than a proven phenomena where riders who just spent money on some sort of gimmicky performance mod and will openly attest that they now feel the benefits of that mod when in truth many times they have lost horsepower.
(Now I just feel like being an ass)
LET US ALL BOW TO MIGHT MIGHTY KNOWLEDGE THAT IS LORD DUCKHUNTER!!! again, I say get over yourself, in your own words, "this mod works" as to the best of my knowledge, completed the mod the same way everyone else does, I didn't notice a difference, So no, on my bike it didn't. and what I'd really like to know is where do you get off telling someone the "lack the experience" Ok, so you know more about tuning the bike then I do. Maybe I choose to ride mine instead of mess with it. So, at this point I'm done because there's no reason to try and act all hardcore on a keyboard. So, with that being said, you can go to your garage and fondle yourself to your socket wrenches because, You know more than I do about the bike, so I must be a noob...
i've definitely noticed the power surge and am trying to smooth things out
. Get over yourself and realize that everyone's bike isn't the same.
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