Vacuum Line to Flapper Valve

the Honda dealer called and said they found a disconnected and Plugged Vacuum line to the flapper valve?
I have NO CLUE the past history of this machine
will it hurt me if they reconnect it?

I have seen conversations about modding the air box but not about disconnect a vacuum line
please advise and THANK YOU

 

I just plugged mine last night with a golf tee and stuck a marble in the pair hose. This mornings commute was much less twitchy and jerky.

 

Excellent
I confirmed that the snorkel is also MIA so I told them to NOT re hook it up
this site ROCKS thanks for all the info I am able to find here searching the forum

 

Totally common mod. Snorkle, flapper, and PAIR.

Take out the snorkle, plug the flapper, and disable pair. It's up to you if you want them to reconnect it.

 

I think I will leave them out It rode pretty damn good on the way home VERY smooth throttle response all the way thru the tach.

 

The flapper helps keep air speed into the airbox at about the same. At low rpms its closed and air can only get in by a 4.5" by 2" hole. At high rpms the flapper is open and doubles the inlet size. As for twitchiness, having the flapper disconnected or not has mad no difference in how my bike handles at any rpm range. Having the pair system disconnected made a difference, mostly in low speed throttle handling. Most noticable change has been the snorkel removal and gutting the stock exhaust cans.

 

The surging that I used to have at low speed low rpm was in perfect time with a sound from the air-box that sounded like the flapper opening and closing. I disabled it and plugged the pair hose with a marble at the same time. now the surging is gone as well as the sound from the air box. Don't know if it is from one or both of the mods but it is gone so it doesn't' matter to me. I know that different people with different bikes in different climates have different results. You can always hook it back up and see for your self if it makes any difference on your bike.

 

nope its modded and I loved it!!
and its not throwing any codes so I'm good!!
don't want to mess with it other than making it safe and ride able

 

If the line is disconnected and plugged that means the flapper never opens, right? Shouldn't the flapper itself be removed from the box?

 

The flapper is held open by a spring, and pulled shut by a vacuum diaphragm. Vacuum from the manifold is used to suck the flapper shut, and an electric solenoid valve controlled by the ECU turns the vacuum on or off. This means a disconnected vacuum pipe will leave the flapper always open. The ECU has no way of knowing whether the vacuum is connected or not so won't throw it's toys out of the cot if you disconnect it. The vacuum hose should be plugged as you would not want a stray air leak into the manifold (although I think there might be a one-way valve in there to stop that).

 

Ahh... OK. I think that means the flapper was broken on my bike. It was closed with the hose disconnected, so I just removed the actual "flapper" piece. I left the hose connected to the actuator to avoid a vacuum leak and everything seems fine.

Thanks for the explanation.

 

all I know is this bike is super smooth thru the whole tach!!!
I get some occasional Popping during shifting or deceleration but it rides and sounds AMAZING

 

I just blocked off the PAIR on mine & it made a HUGE difference in power & smoothness below 3000 rpm.

 

Is there a pair valve on my 99 5th gen? I think my bike doesn't have 02 sensors in the exhaust, my model has the 'choke' or fast idle control on the handlebar,
I have a scorpion end can and it pops on deceleration, not really a problem, but anyway sitting around now and can't ride in the evenings because of lockdown so looking at doing some mods, I might pull the snorkel out and block the vacuum line to the flapper, just not sure if my bike even has a pair valve, thanks.