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PAIR Valve Mod
Author Message
Joola Offline
Running Like a Top

Los Angeles
Posts: 267
Joined: Jun 2013
Post: #1
PAIR Valve Mod
Big thanks to Deanohh and HondaJon for this mod. I'm running a Staintune, PCV and a K&N Filter. The decel popping got worse after I installed the PCV so I decided to try this mod out. It was super simple, took less than 5 minutes and worked flawlessly.

Background:
Here is a page from the official service manual explaining what the PAIR Valve does. It's only an emmission control device.

Cost:
< $1.00

Tools Needed:
  • (1) 3/8" or M10 Cap Screw
  • Hands
İmage

Process:
Locate where the PAIR air supply hose connects to the PAIR valve. It's the forwardmost hose under the gas tank. Slide back the hose clamp and pull the hose off the valve. I was able to release the clamp and remove the hose with my fingers.The tank does not need to be removed to complete this mod but it would make it easier.
İmage

Jamb the cap screw into the hose (it's a tight fit) and push it in so a small portion of the bolt is protruding from the hose. This will allow you to remove it easier later if needed. I pushed the screw in farther than in shown in the picture below.
İmage

Reattach the PAIR air supply hose the the valve and slide the hose clamp back on. That's it!

Conculusion:
I tested the mod briefly by riding around the block, revving to ~6000RPMs and decelling. I did this in both 1st and 2nd gear. The popping was gone COMPLETELY. I should mention that you will notice your exhaust emissions when you're idling. I was able to smell carbon monoxide while idling in a parking lot. I'd never smelled that from my bike before. So there is a small drawback to this mod.

Beer

[size=x-small]719 Gel Grips, Tandem Grip, Chrome Chain Guard and Meter Covers, K&H Hi Seat, Lucas Taillight, ViziTec Modulator, Painted Headlight Bucket[/size]
(This post was last modified: 12-21-2013 03:10 PM by Joola.)
12-21-2013 03:10 PM
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SUPERCRUZ Offline
1st Service Completed

NOVA
Posts: 194
Joined: May 2013
Post: #2
RE: PAIR Valve Mod
Joola - Nice write up. Very informative. In the Triumph circles, I know guys there would use a marble in the inlet air hose to block off the air system on the Bonnevilles. Just another option those performing this mod might consider to block off the inlet air hose.

Triumph - 2011 Bonneville SE, Honda - 1968 Mini Trail Z50A, 2013 CB1100
12-21-2013 05:38 PM
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Deanohh Offline
Running Like a Top

Redmond, Wa
Posts: 563
Joined: May 2013
Post: #3
RE: PAIR Valve Mod
The other caveat is that this is definitely tampering with the emission control system and could land you in the Federal Pen, as well as causing acid rain, melting of the north pole, dead polar bears, dead whales, rain forest depletion, rising sea level, increased cancer, and shortened life expectancy, and increase in Al Gore's bank account. Therefore this mod is certainly not recommended by this forum or anyone else using the interwebs at this time.

Even though if this was done to every Honda motorcycle ever built and the difference in emissions was added up for all of them for the lifetime of the bikes, the total would be less than what comes out of one 747 flying for 10 seconds.

Also a socket head capscrew of the same size has a cylindrical round 16mm head which works very well.

2011 Triumph Street Triple R
2014 Yamaha FJR1300A
(This post was last modified: 12-21-2013 06:43 PM by Deanohh.)
12-21-2013 06:29 PM
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The ferret Offline
Forum Moderator

Ohio
Posts: 31,283
Joined: Apr 2013
Post: #4
RE: PAIR Valve Mod
Well, I certainly don't want to add to Al Gores bank acct. he already has a big enough footprint on this planet.

.
Defender of the Realm
2014 DLX (the pleasure horse)
2021 NC750X DCT (Angry Bird)
12-21-2013 08:22 PM
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HikerToo Offline
Road Warrior

Delaware
Posts: 1,519
Joined: May 2013
Post: #5
RE: PAIR Valve Mod
So the hose will go back on to the same place even though the bolt threads are near or at the hoses opening?
And.......there is no risk of this bolt getting "into" the engine somehow?
06-09-2014 04:14 PM
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Ridem32 Offline
Road Warrior

Mississippi
Posts: 1,573
Joined: Apr 2014
Post: #6
PAIR Valve Mod
I will have to do some research on this. I have never looked at the hose! So I'm not sure if it's a crankcase breather hose. But I'm sure it's been checked out before. If not it could build psi and blow engine seals and cause oil leaks.
06-09-2014 09:02 PM
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Joola Offline
Running Like a Top

Los Angeles
Posts: 267
Joined: Jun 2013
Post: #7
RE: PAIR Valve Mod
(06-09-2014 04:14 PM)HikerToo Wrote:  So the hose will go back on to the same place even though the bolt threads are near or at the hoses opening?
And.......there is no risk of this bolt getting "into" the engine somehow?

Hose goes back on the same place. Threads fit inside but the bolt head is larger than the port so it's not possible for it to get sucked in.

I've ridden a few thousand miles with this mod and have experience no ill side effects. The hose only adds air at the exhaust port. It's not an essential engine fuction. It's only for emission control.

[size=x-small]719 Gel Grips, Tandem Grip, Chrome Chain Guard and Meter Covers, K&H Hi Seat, Lucas Taillight, ViziTec Modulator, Painted Headlight Bucket[/size]
06-09-2014 09:33 PM
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CIP57 Offline
High Mileage

NY & NC
Posts: 1,410
Joined: May 2013
Post: #8
RE: PAIR Valve Mod
(06-09-2014 04:14 PM)HikerToo Wrote:  So the hose will go back on to the same place even though the bolt threads are near or at the hoses opening?
And.......there is no risk of this bolt getting "into" the engine somehow?

Pair systems are not put on bikes in certain markets. The function is to cool gases before the get into the Cat for better burn rates to pass emissions. Pair systems get filled with carbon over the years of service and don't even function. Pair's only function is on decel and does not increase HP gains nor does it hurt performance. The one benefit is the decrease in back pressure and popping. Some people say there's a decrease in engine breaking, myth not sure. When i put my full exhaust it eliminated all popping.

As far as the bolt, i installed mine with just enough exposed to pull it out. It's not going to go anywhere or cause damage.

1982 Suzuki GS1100EZ
06-10-2014 05:52 AM
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Dengie Boy Offline
1st Service Completed

UK
Posts: 59
Joined: May 2014
Post: #9
Re: PAIR Valve Mod
...I have a question - the air leaves the air filter and travels to the PAIR valve, it then either goes to the exhaust ports and or doubles back to? Does this other hose connect to the crankcase as part of that emission control as mentioned in the manual or?...
(This post was last modified: 06-10-2014 12:29 PM by Dengie Boy.)
06-10-2014 09:20 AM
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Gumby 1100 Offline
Running Like a Top

Cambridge, Ontario, Canada
Posts: 489
Joined: May 2014
Post: #10
RE: PAIR Valve Mod
(06-10-2014 05:52 AM)CIP57 Wrote:  The function is to cool gases before the get into the Cat for better burn rates to pass emissions. Pair systems get filled with carbon over the years of service and don't even function.

Actually, the PAIR system is designed to detonate unburned gasses and reduce polutants in the exhaust. It injects filtered, fresh air after the exhaust valves which mixes with any unburnt gasses and is ignited by the heat of the exhaust system (or headers). This would tend to make the headers and any gasses reaching the catalytic converter hotter, not cooler. The benefit is that there would then be fewer unburnt gasses to precipitate onto the catalytic. The catalytic convertor needs to be hot to function and to keep unclogged, but ordinary exhaust gasses are generally hot enough to take care of that.

One thing that is hard on catalytic convertors is the use of Premium fuel in an engine designed for regular (like our CB1100). Higher octane inhibits combustion and more unburned fuel will pass over the catalytic, potentially clogging it, as well as fouling the spark plugs.

It is also very unlikely that the PAIR System will get carboned up as it is only receiving filtered air. The PAIR valves and REED valves are all ONE-WAY and on the fresh air side of the system. There is no way for combustion gasses to revert into the PAIR system to contaminate it and prevent it from functioning. Unless you bypass it, the PAIR system will likely continue to function for the life of the bike. In fact, certain methods of bypassing the PAIR valves, like "Marbling" or simply plugging the inlet to the PAIR valve in the air box can contribute to condensation forming in the system. This condensation can occasionaly get sucked thru the REED valves and you may see a puff of white smoke exiting the exhaust. This generally will not cause any issues and is a similar effect to "water injection", but the moisture may eventually cause corrosion in the PAIR system and could potentially make the REED valves swell and stick open.

An interesting point brought up by Dengie Boy:
Blocking the PAIR system may help to prevent header discolouration as they should run cooler without the PAIR system.

2014 CB1100A (Canadian) #068 (Sold)
2018 Harley-Davidson Road King
(This post was last modified: 06-10-2014 10:21 AM by Gumby 1100.)
06-10-2014 10:02 AM
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