PAIR and Flapper removal

Hi Guys.

Looking for people to share their experience and opinions about removing the PAIR valve and air box flapper. I've done some searching on this forum and there doesn't seem to be much consensus. It seems like it does make good sense to remove the PAIR valve on a gen 6 bike if the PAIR conflicts with the oxygen sensors but maybe it's not necessary on gen 5 bikes? The air box flapper is part of the PAIR system, right? So if the PAIR is disabled why not get rid of the flapper. It does not make sense to me to remove the air box snorkel.

The reason this is coming up for me is that I've installed an Power Commander III usb with a generic fuel map and I'm thinking about having a local shop check valve clearance and create a custom map. If I go with a custom dyno tune I'd like to do all the work necessary going into this. I've got a 1998 VFR 800 non California model with a K&N air filter and a micron high mount slip on silencer. 16,000 miles - Just got it a few weeks ago.

The bike's performance seems fine, so I don't know how crazy I need to get here. There is some popping on deceleration which seems worse now that the Power commander is installed but I've heard that removing the PAIR valve helps this. I did also notice that the Power Commander smoothed out the power in first gear.

I know this topic has been discussed already but anyone have something to say?

 

This is always one touchy subject as there are many different opinions and comments to be sure. The one thing I am sure about is that you do have to remove or disable the PAIR valve system in order to get a proper Dynotune, this was confirmed by several Dyno tuners and Dynojet themselves, so if that's the direction you are heading you're on the right path. I would just move forward with the Dynotune and see how she purrs after that.

Cheers!

 

I removed my flapper valve first just for a little more intake noise. I then removed the pair valve nearly 3 years later and could notice a smoother idle and helped with the abruptness right off idle. It was nothing huge but I could definitely tell a difference. I have a 98 with a k&n filter and stock exhaust. To me all that stuff is just there to please the epa and I'm not to worried about them.

 

Total newbie queston here, How do I remove the pair valves and the flapper, I have an 01 vfr800 fi, thanks

 

The flapper is the easy one but the PAIR is a little more involved. To get to the flapper, unbolt the front of the gas tank and tilt it back, remove the top of the air box, Note: the hose that you have to disconnect to remove the top of the airbox is the vacuum line that controls the flapper valve. Once you have the top of the airbox off, remove the vacuum actuator and tape the hole up and either tape the flapper open or remove it completely. Now you can put the airbox back on but be sure to plug that vacuum line that you disconnected earlier. Put a small screw in the line and zip tie it. Flapper is done!

The PAIR valve is much more complex and there should be a very thorough post on it here...http://vfrworld.com/forums/5th-generation-1998-2001/35929-how-pair-removal-5th-generation.html
Note that if you are going to remove all of the bits and pieces of the PAIR valve you might want to look at getting "block off" plates before you head down that road, anyway, follow the link above and good luck!

Cheers!

 

Thanks, so now I don't know what the 'vacuum actuator is' and where the flapper is, I presume they are in the airbox cover, there is a thing looks a bit like a thermostat where that vacuum pipe attaches, is that the flapper?

What are the advantages of removing the flapper valve and the snorkel? I already have the snorkel out.

I will leave the pair valves go till I figure this out first.

 

Maybe that is not the best name for it, but yes it looks like a thermostat, basically the device (acutator as I called it) lifts and lowers the flap via the vacuum line. Removing it essentially "opens up" the airbox more and increases the intake growl, for top end it should allow for more airflow but for low/mid range you will lose what it was intended for.

 

Thanks, I think I 'half' understand what you are saying,i will have a look at her and see what I can figure out. I was thinking if I have to do a valve check wouldn't it be a good time to replace the real thermostat? preventative maintainance ?
does the throttle body have to come out to check the vale clearances, you can tell I haven't much of a clue,but I am willing to learn,the hard way probably,thanks again.

 

Once you look under the tank and see the top of the airbox, it'll all make sense. As far as the "real" thermostat, you will need to take off the throttle bodies to replace it, so if you're going to do a valve check, it might be worthwhile looking into.

 

I hear ya, don't think I'll mess with it, must get the starter valves synched and the valves checked, from what I have read the starter valve synch is easy done,the vacuum pipes being up at the side of the air box.
One thing that is annoying me the vibration in the footpegs.left one is very bad, anyone ever tried putting rubber washers etc around the mounting bolt,it is bloody annoying.

 

I don't recomend getting rid of the flapper valve.
Inside the air box, you have the velocity stacks that feed air into your cylinders, these optimise the air flow so that it flows in smoothly and at an even rate, and all cylinders get the same amount.
At high engine revs, the air flow changes so that it is no longer optimised to flow into the velocity stack in the same way as at slow revs.
The flapper opens to change the way the air flows in, and to again optimise the air flow into the velocity stacks.
In theory, you will lose some low down grunt if you get rid of it and keep it open all the time, but you might not notice it.
Great engine designers like BMW, Mercedes, Porsche and so on, have been using this type of technology for years, sometimes in a much more complicated way but all for the same purpose.
Optimising air flow at changing engine speeds.
They are not there as noise or polution control.
Pair valves are a different story, messy and of no performance help whatsoever, only there for polution control.
I got rid of mine just to clear up some space and get rid of popping during decel.
It sounds better now but has made no change to performance.
Hope I was some help.