Filthy PAIR valves

First thing pretty much every Honda VTX1800 owner does is block these off and remove the rest of the poll control stuff - not so much in the st crowd and I wonder why?

no hijack intended - just putting this out there as I doubt the cleanliness even has any effect??
 
I also cannot remember what the inside of the PAIR valves look like but if you are not experiencing driveability issues and/or popping and backfiring then the PAIR valves are not causing any issue worth worrying about IMO.
 
Not exactly sure how the ones on the ST work but in other applications it could be a sign of high crankcase pressure. Nothing critical. But is there a crankcase breather/pressure valve on the 1300?
 
Pair valves on my 90,000km VFR800 looked exactly as you describe. These are reed valves and so close with exhaust pressure and open with exhaust vacuum. If there was only ever vacuum, then you wouldn't need a reed valve. Quit worrying.
 
The PAIR solenoid opens on deceleration to allow air to passively flow into the exhaust to help with unburned gasses. You may hear popping in the exhaust occasionally as a result. At other times the reeds close with exhaust pressure to prevent backflow. Completely normal to carbon up, gently clean and reinstall or as some do, remove the PAIR system and replace with block-off plates.
 
RaYzerman said:
The PAIR solenoid opens on deceleration to allow air to passively flow into the exhaust to help with unburned gasses. You may hear popping in the exhaust occasionally as a result.
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I can’t let this commonly held but erroneous idea go. Pet peeve of mine.

Honda PAIR valves are open during normal operation, adding filtered air continuously to the exhaust manifold to help burn hydrocarbons in the exhaust, reducing pollution.

BUT — during high intake manifold vacuum like when quick rolling off the throttle/engine braking/deceleration, large amounts of unburned hydrocarbons are dumped into the exhaust manifold. At that time the PAIR valves are CLOSED to stop the filtered air from being added to the exhaust manifold so that AFTERBURN (“backfire” occurs in the intake manifold) is prevented.

Edit: to be clear - during decel the PAIRS cut off air so there’s no big damaging bangs, but you’re polluting.

Check the Service Manual for other causes other than a properly functioning PAIR system if you experience genuine afterburn. “Decel burble” is normal, even on non-PAIR equipped engines.

Please do not perpetuate this errorneous operational concept. Read the description of your engine’s exhaust emission control system in the service manual.

John
 
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I have read a couple of posts and articles about disabling the honda (and other makes) PAIR system. It usually involves a couple of marbles and/or some block off plates. Last time I had my head covers off, I looked at the dirty reed valves,,, but then decided to just leave them alone. I also noticed that I had some oil mist in the intake box,, surrounding the pair hose inlet. All that made me wonder if it was functioning as intended. BlueSTar is running great, at 196,000kms, btw. Performance minded wrenchers seem to just disable the pair system without much thought,,, because they believe that doing so improves performance. What say you who understand the setup ?? cheers, CAt'
 
Catmandu2 said:
Performance minded wrenchers seem to just disable the pair system without much thought,,, because they believe that doing so improves performance. What say you who understand the setup ??
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The PAIRs on STs are a passive system and have no effect on performance, other than the additional weight of the components. Please read the service manual’s description.

John
 
That’s about right, John. I don’t have an ST1300 manual so am not fully conversant on its emissions control system other than it operates similarly to the ST1100’s - filtered air ceases to enter the exhaust manifold during decel/engine braking. The ST1100 is vacuum operated and as I understand it the ST1300 is solenoid operated.

Don’t claim your PAIR valve(s) have failed and are somehow causing problems on your ST until you’ve done the inspection detailed in the service manual. The check for ST1100s is dead simple, the short-cut method only takes a couple of minutes.

John
 
Its a fairly common modification for bike owners to strip out the PAIR valve system. It has no effect on performance, eliminates the pop pop on decel and cleans up the internal engine compartment.
I have done the job both on the VFR and Valkyrie... (I make block off plates for the VFR) -- The ST1300 looks like it would be simple to do too with block off plates.
I could make those if people wanted them... The job entails, pull reed valves, clean it up, bolt on cover, and then pull the pump off the bike and plug any open vacumn ports.

VFR cover looks like...
1574923926191.png


btw - where is the thing in the fische?
 
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mello dude said:
It has no effect on performance, eliminates the pop pop on decel ……..
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John OoSTerhuis said:
Sorry, it does not. But if you really think it does, please try and explain how...

Respectfully, John
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Gotta agree with mellow dude. When I put 2 Brothers cans on my 1300 I heard the popping that I didn't hear with the stockers. I removed the PAIR system and popping is 90% gone.
 
Whooshka said:
I removed the PAIR system and popping is 90% gone.
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And how exactly did removing the PAIR valves do that?

Consider that during deceleration with PAIRs installed there is no air entering the exhaust manifold. And with the PAIRs removed there also is no air entering the exhaust manifold. No large bangs (afterburn) either way. And if there was some decel burble before the PAIRectomy there will be some after... nothing has changed in the exhaust manifold.

On the ST1100 the next suspect for afterburn would be the air cut-off valves.

Sorry... if you want to remove the PAIR valves and pollute all the time instead of just during engine braking, just do it! Please don’t rationalize your actions and perpetuate erroneous info.

Again... respectfully, John
 
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mello dude said:
Its a fairly common modification for bike owners to strip out the PAIR valve system. It has no effect on performance, eliminates the pop pop on decel and cleans up the internal engine compartment.
I have done the job both on the VFR and Valkyrie... (I make block off plates for the VFR) -- The ST1300 looks like it would be simple to do too with block off plates.
I could make those if people wanted them... The job entails, pull reed valves, clean it up, bolt on cover, and then pull the pump off the bike and plug any open vacumn ports.

VFR cover looks like...
1574923926191.png


btw - where is the thing in the fische?
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correct in that when you remove the cats from a bike ( assuming there is no down stream O2 ) with an air system the air system becomes redundant. on a bike with cats the air system adds air to help reignite unburned hydrocarbons which also keeps the cats hot which helps with cat efficiency. on the ST this is a HUGE creator of heat on a bike that already has heat problems :( if you take out the cats the pop pop noise your hearing is the igniting of the unburned hydrocarbons so when you remove the air system the unburned hydrocarbons do not reignite but just leave making the bike smell "sweeter" LOL
I should note that bikes with cats NEED the extra air to keep the cats hot or they will eventually clog

there are lots of ways to disable the air systems. On my ST I just took off the valve and hose then installed caps in the reed valve covers. This was the free option :D
 
jfheath said:
I'll probably take out the lower [fuel] tank, see if I can get to the gear pedal linkage on the left side of the bike.
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Wow, that is the ultimate ST 1300 disassembly job. My understanding is that when Honda begins to build a ST 1300 on the assembly line in Japan, the first thing they do is place the lower fuel tank on the jig. The workers then wrap all the other stuff - frame, engine, wheels, other useful parts- around the lower fuel tank. :)

Do take pictures of the process for all of us if you decide to go after that elusive lower fuel tank.

Michael
 
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