pair valve





#3
The PAIR valve is part of the emissions equipment on the Busa and other Suzuki bikes. It is does not affect the performance of the bike, since the effects it has are in the exhaust headers, not the power producing engine. It introduces fresh air into the exhaust to burn off any remaining fuel -- thereby making the exhaust "cleaner".

Having written that... Once an aftermarket full system exhaust is put on the bike, it is best to remove the PAIR valve. Since the fresh air put into those pipes by the PAIR will cause back-firing which could damage the engine.

So, removing with PAIR will improve HP insofar as having a new exhaust system will improve HP and removing the PAIR is usually done at the same time.
 

monsterspeedfreak

Donating Member
Registered
#4
This is what sleeper busa has seen with the pair valve:
The pair valve removed is just taken off and the holes blocked.
It doesn't do much excpet get it out of the way and keep the bike from backfiring during decelleration.
The Pair MOD is when you route one of the hoses to the crank case vent and cause a vacuum within the crank case. That helps the rings seal better on the cylinder wall.
It's been used in drag racing for years.
If those pros do it, you can bet it helps.
I have it done on my bike, but thats just me. I want every 1 hp that I can get!

Is it worth taking the bike down to do? NO.
If your body is already off?
Sure, why not?

If the motor is fresh, you might see 1-2 hp.
My Buddy has like 16,000 hard miles and it made 3 hp on his.
Back to back, removing and reinstalling it, 3 times with dyno pulls to back up his findings.

It might be because his rings are a little loose and they could use the help that the vacuum offers??

Hope this helps.
 

Narcissus

Hayabusa Immortal
Moderator
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#5
It screws with the the A/F measurements when dyno tuning. Just be sure to block it off when making maps.
 

rubbersidedown

BUSA-RIDIN'-BASTID
Donating Member
Registered
#6
The Pair MOD is when you route one of the hoses to the crank case vent and cause a vacuum within the crank case. That helps the rings seal better on the cylinder wall.
It's been used in drag racing for years.
If those pros do it, you can bet it helps.

My Buddy has like 16,000 hard miles and it made 3 hp on his.
Back to back, removing and reinstalling it, 3 times with dyno pulls to back up his findings.

It might be because his rings are a little loose and they could use the help that the vacuum offers??
I have real trouble with this one . A little bit of vacuum(less than yer average 60 dollar vacuum) is gonna get up a cylinder wall past a CYLINDER TO PISTON CLEARANCE of like , (I'm gonna guess here , instead of getting out my manual) a clearance of around 0.0015-0.0020 in. somewhere around there . .040-050 for u metric dudes . Vacuum is gonna get up there an actually pull a ring closer to the cylinder wall that it is already scrapping . I dunno .
I have trouble with this . Vacuum effect on a moving object , lets say yer just cruising , at...5000 RPM.
The rings are travelling thru this vacuum ( a 3 dollar hoar could suck more) . Wouldnt the rapid up/down motion of the piston cancell out any tiny bit of vacuum?
I personally think whats taking place is that there are less blow-by gases in the crankcase , because of the vacuum , and with the reduced gases,there is less force on the bottom of the piston as it comes down to BDC . It's blo-by that makes yer oil dirty right? There's only a couple ways into yer motor right? It comes in as fuel , or it comes in as air . I can see vacuum helping to remove these blo-by gases , but I cant see them helping the sealing between rings an' wall . It's the pressure of the piston coming up to TDC compressing the F/A mix that actually does the sealing . Whats a busa compression ratio ...I forget...12 to 1 or something....maybe 13 to 1 . Thats gonna give you compression pressure in the neibourhood of something like 150-225 PSI . Thats a pretty respectable neibourhood .
Some of the F/A mix gets behind the rings forcing them to the wall . It's this pressure that causes them to seal . I dont think a couple of hundred pounds per square inch of pressure is in need of , or is going to be able to obtain any benefit from, some miniscule amount of vacuum in the crank case.

Drag racers have been doing this for years . Maybe HUGE amounts of vacuum can have the pulling effect on the rings,that might help , maybe a Keith Black or Reher/Morrison 500 cubic inch can provide the vacuum nessesary to do this.I doubt it .

Vacuum requires space to be effective doesn't it ? How is it going to get thru a space thats only 15,000 of an inch ?

More research into this might be required , on my part for sure.....I'm dyin to know the real answer .
 

rubbersidedown

BUSA-RIDIN'-BASTID
Donating Member
Registered
#7
The Pair MOD is when you route one of the hoses to the crank case vent and cause a vacuum within the crank case. That helps the rings seal better on the cylinder wall.
It's been used in drag racing for years.
If those pros do it, you can bet it helps.

My Buddy has like 16,000 hard miles and it made 3 hp on his.
Back to back, removing and reinstalling it, 3 times with dyno pulls to back up his findings.

It might be because his rings are a little loose and they could use the help that the vacuum offers??
I have real trouble with this one .  A little bit of vacuum(less than yer average 60 dollar vacuum) is gonna get up a cylinder wall past a CYLINDER TO PISTON CLEARANCE of like , (I'm gonna guess here , instead of getting out my manual) a clearance of around 0.0015-0.0020 in. somewhere around there .    .040-050 for u metric dudes .  Vacuum is gonna get up there an actually pull a ring closer to the  cylinder wall that it is already scrapping . I dunno .
   I have trouble with this .  Vacuum effect on a moving object , lets say yer just cruising , at...5000 RPM.
The rings are travelling thru this vacuum ( a 3 dollar hoar could suck more) .  Wouldnt the rapid up/down motion of the piston cancell out any tiny bit of vacuum?
 I personally think whats taking place is that there are less blow-by gases in the crankcase , because of the vacuum , and with the reduced gases,there is less force on the bottom of the piston as it comes down to BDC . It's blo-by that makes yer oil dirty right?  There's only a couple ways into yer motor right?  It comes in as fuel , or it comes in as air . I can see vacuum helping to remove these blo-by gases , but I cant see them helping the sealing between rings an' wall .   It's the pressure of the piston coming up to TDC compressing the F/A mix that actually does the sealing . Whats a busa compression ratio ...I forget...12 to 1 or something....maybe 13 to 1 .    Thats gonna give you compression pressure in the neibourhood of something like 150-225 PSI .  Thats a pretty respectable neibourhood .
Some of the F/A mix gets behind the rings forcing them to the wall . It's this pressure that causes them to seal . I dont think a couple of hundred pounds per square inch of pressure is in need of , or is going to be able to obtain any benefit from,  some miniscule amount of vacuum in the crank case.

 Drag racers have been doing this for years .  Maybe HUGE amounts of vacuum can have the pulling effect on the rings,that might help , maybe a Keith Black or Reher/Morrison 500 cubic inch can provide the vacuum nessesary to do this.I doubt it .  

  Vacuum requires space to be effective doesn't it ? How is it going to get thru a space thats only 15,000 of an inch ?

 More research into this might be required , on my part for sure.....I'm dyin to know the real answer .
YA.....what he said......hee hee hee...
 
#8
First of I'm no mechanic and I don't know a lot about motors. But this what I DO know!! If your one of those that are having backfiring problems...put on block off plates NOW! I can not stress how important it is...but I'm going to leave you with this little story. Oh before I get into the story "they" say you get 2-5 hp from using block off plates. But who knows... So now the story:

This is a VERY serious problem that should not be taken lightly!! I know first hand! I'm going to give you alittle history on my busa. I bought the bike in New Mexico elevation eh...about 5k feet. No problems with back fire whatsoever at this time, back in 2000. Once I moved to Okinawa Japan where I was about 10 feet above sea level I've gotten massive backfires!! The mechanic told me to becareful and not to ride it too hard cuz it going to mess your engine up...this was in Feb of 2002 or so. I was like yeah whatever that blue flame is lovely. Kept riding it...about November time frame he said he knows what the problem is...get the Block off Plates that cost about $40 bucks to solve your backfire problems. I ordered them...but didn't install them. In January of 2003...two up racing through the streets of Okinawa...one hell of a back fire happened. And I heard the strangest sound afterwards...like a nasty grinding sound. Needless to say my engine was toast! The head gasket went and so did all my oil, the crank, bearings, pistons and hell of alot of other things. I'd say around $4k of damage if I was putting all stock parts back in...but I figured might as well do it right. Everything pretty much after market being replaced. And I'm still working on this damn bike now. We about $6.2k in repairs and replacements.

So I'm going to tell you like this...get the Block Off Plates to end your backfiring! And do it quickly! Only $40 dollars can save you thousands!

That was from another post I made ealier today. But I think it applies here. You don't need that damn thing...but if your complete stock...not even slip ons, you should be alright. But if you got some slip ons and anything else done...remove the damn thing immediatly!!
 

monsterspeedfreak

Donating Member
Registered
#9
Good call on Daddy's part on this.
I am 6' above sea level and had horrendous backfiring.
Made my own plates in 20 mins installed them in an hour and no backfiring at all.........way nicer to ride!!!!
 

Revlis

Re-Recycled, Busa-Less...
Donating Member
Registered
#10
I am with rubbersidedown on the vacuum helping the rings seal...huh? But being useful to evacuate blow-by gasses and to function as a "power crankcase blower" could be real useful. Help keep your oil happy and healthy.

On another note, will removal of the pair and installation of bolt ons effect my warranty?
 
#11
pair valve removal = reduced to no chance of engine damage due to backfires

pair valve removal = LIGHTER BIKE!

surprised I was the first one to say THAT in this thread.
sneaky.gif
 
#12
I don't care how happy you think your oil is due to the pair valve. But if your backfiring, you NEED to take it off! You WILL damage your engine. There is no if, and, or buts about it! Its only a matter of time.

You are correct Cache...but I'm not sure if your the first to say it. OH darn I didn't mention the lighter bike part. *kicks self*
 
#13
What magnitude of backfire were you guys having? We are having some small little "poofs" coming out only during decelleration while in gear.
 
#14
The decell backfires is what they are refering too. Some are worse than others.
Remove the pair and block off the holes in the head and it will go away.
 
#15
OKAY, OKay, okay...... stupid ? here...

this backfire you all 'know'... describe the intensity and sound it makes... mine under decel does like a "grubb blub blib" mostly just a gurgling lean sound, nothing massive or anything... not POW! POW!..........

So what kind is it you all are talkin about?
 
#17
Mine was a major backfire for over one years time. It was cool as hell...I was blowing out 1-1½' worth of fire coming out both pipes. My nickname was Blueflame! It was so pretty. But now my engine is completly tore apart and waiting for parts to come in.

So the moral of the story is...doesn't matter if you have a little bang...or a the big boom happening...remove that pair valve and put on those block offs! It will save that engine. I can't express how important those $40 slabs of metal are.
 

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