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Discussion Starter #1
So I've recently read about a purge valve mod you can do to lean off the fuel air mixture to eliminate back fire of unburnt fuel when throttling off.

So being me I went and blocked off the purge valve secondary air house leading to the air box then took it for a ride i didn't really notice much difference apart from it did eliminate most of the burbble. But being me I wasn't happy with just blocking off the purge valve, so instead I cut a piece of old air filter sprayed it with K&N filter oil and tie rapped it to the end of purge valve hose. Then I blocked the outlet from the air box. I didn't bother with the after market blocking plates as I wasn't bothered about weight reduction by removing the second air assemblyand associated house as the bike is already running 4kilos lighter than stock. Plus I wanted an easy fix if things didn't go as planned.

My thinking was I know have the best of both worlds.

On the test ride I noticed a considerable difference in low rev range which felt like I gained a couple of horse's. I can only speculate but I'm putting this down to the increased air pressure in the air box at lower revs, giving the bike a slightly leaner burn and making use of the excess fuel. Also by keeping the purge valve intact I didn't have to worry about throwing an f1 light or cut any wires. Also by adding an air filter I could ensure clean air is drawn into the engine.

My bike was already running slightly rich anyhow!

Are my assumptions correct? as every where I've read seem to say it makes no difference what's so ever. Apart from increasing emissions and eliminate back fire. But this doesn't translate into how the bike felt on the test?

Any thoughts or personal experience of similar gains if any?

Many thanks

Clin
 

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meh, good full system mod, as you said minimizes pops and backfire, not known to get any real HP gains I don't think?

after a certain generation you will have an ECU input to the pair system, 2010? hale I forget, ronayers microfiche should let you know if yours has an electrical lead, they make the adapter kits for em
 

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"Also by adding an air filter I could ensure clean air is drawn into the engine."
I'm lost. The PAIR system adds air to the engine exhaust to promote burning of unburnt fuel in the exhaust. The added air comes from the air box. The popping comes from the added air being turned on and off. There are two PAIR mods, the more common one just blocks off the PAIR system. The absence of added air means that the exhaust gases are slightly richer, not leaner. The other connects the PAIR system so that it draws air from the crankcase instead of the air box. This creates a vacuum in the crankcase, which reduces pumping losses and increases horsepower. The reality is that the vacuum isn't very big and the gains are minor at best. Furthermore they're going to happen at high RPM.

You seem to be doing something completely different. Air isn't drawn into the crankcase. Instead vapors associated with blowby come out. If you're seeing a boost at lower RPMs, you've either discovered a new phenomenon, you've made some other change, or it's imaginary.
 

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"Also by adding an air filter I could ensure clean air is drawn into the engine."
I'm lost. The PAIR system adds air to the engine exhaust to promote burning of unburnt fuel in the exhaust. The added air comes from the air box. The popping comes from the added air being turned on and off. There are two PAIR mods, the more common one just blocks off the PAIR system. The absence of added air means that the exhaust gasses are slightly richer, not leaner. The other connects the PAIR system so that it draws air from the crankcase instead of the air box. This creates a vacuum in the crankcase, which reduces pumping losses and increases horsepower. The reality is that the vacuum isn't very big and the gains are minor at best. Furthermore they're going to happen at high RPM.

You seem to be doing something completely different. Air isn't drawn into the crankcase. Instead vapors associated with blowby come out. If you're seeing a boost at lower RPMs, you've either discovered a new phenomenon, you've made some other change, or it's imaginary.
Very well could be imaginary It Maybe just the ambient tempiture was cooler on that puticula day but it did seem as though it had more to offer. Never thought about connecting crank case pressure.it sound interesting and worth a trying. My only thought is don't the secondary air rely on clean cool air to ignite excess fuel, surly by connecting it to the crank breather there wouldn't be that much clean air through the system hence not igniting unspent fuel? Tomorrow I'll take a pic and do another test so you have a butter idea what I've dune. If it is a new phenomenon that would be cool, but I doubt I'm that lucky lol
 

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The other connects the PAIR system so that it draws air from the crankcase instead of the air box. This creates a vacuum in the crankcase, which reduces pumping losses and increases horsepower.
The reality is that the vacuum isn't very big and the gains are minor at best. Furthermore they're going to happen at high RPM.
I was wondering about what the crankcase pairmod does to oilpressure
I would think getting too much vacuum in the crankcase would starve certain areas of lubrication?
 

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Discussion Starter #7
Ok I've manage to do another test ride and the bike still feel as though it has more to offer! I can only put this down to an increase in air box air pressure one by having the air box blocked and two by pair valve not siphoning off the air at lower revs. I think in light of this the bike would have to run rich to begin with to notice any difference which mine was running rich to begin with!

What I would like to do next is try this setup by connecting the crank case hose and T into make shift filter and pair hose!

I think the aim would be to reduce crank case pressure after gaining hp from a power commander. And i guess the increase in air box air pressure will enable the setup coup with exra fuel. But I haven't got a power commander yet so I guess I'll have to wait. But I'm not sure if re-maping the ecu is a better route to go down!

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I was wondering about what the crankcase pairmod does to oilpressure
I would think getting too much vacuum in the crankcase would starve certain areas of lubrication?
This would be a concern for me too, but I'm guessing if fitted with a power commander an a increase in hp would find an increase in oil pressure too. I assume it wouldn't be worth the risk unless increasing horse power by a considerable amount!
 

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The ram air pressure at 50 MPH is only .04 psi. You need to be above 100 MPH for it to be of any consequence. Any drawn into the PAIR system will be small relative to that consumed by the engine and of no consequence. Dust sucked into the PAIR system is just going to end up in the exhaust gas and not affect anything.

Lower pressure in the crankcase might pull oil out from the various journals and galleys but that might actually be a good thing. I've never heard of oiling problems associated with it. The good car systems with vacuum pumps run much higher vacuum levels than can be achieved with the PAIR system and I'm unaware of the need for different oiling with them.
 

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The ram air pressure at 50 MPH is only .04 psi. You need to be above 100 MPH for it to be of any consequence. Any drawn into the PAIR system will be small relative to that consumed by the engine and of no consequence. Dust sucked into the PAIR system is just going to end up in the exhaust gas and not affect anything.

Lower pressure in the crankcase might pull oil out from the various journals and galleys but that might actually be a good thing. I've never heard of oiling problems associated with it. The good car systems with vacuum pumps run much higher vacuum levels than can be achieved with the PAIR system and I'm unaware of the need for different oiling with them.
Thanks for that this is great stuff certainly a lot to think about when tying to get more for less! I wonder if on later models the introduction of air into the Pair system would eliminate the need to cut wires? Although I have to say, It is satisfying hearing a few burbble burbbles coming into those quaint little villages after the bendy bits!
 

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Ok I've manage to do another test ride and the bike still feel as though it has more to offer! I can only put this down to an increase in air box air pressure one by having the air box blocked and two by pair valve not siphoning off the air at lower revs. I think in light of this the bike would have to run rich to begin with to notice any difference which mine was running rich to begin with!

What I would like to do next is try this setup by connecting the crank case hose and T into make shift filter and pair hose!

I think the aim would be to reduce crank case pressure after gaining hp from a power commander. And i guess the increase in air box air pressure will enable the setup coup with exra fuel. But I haven't got a power commander yet so I guess I'll have to wait. But I'm not sure if re-maping the ecu is a better route to go down!

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I see what you're trying to do. However, you have not done it.
If you think you have, dyno before and after.to really see any reproducible gains. Same dyno, same day.
Did you day what year you have? Sorry, missed it.

Check out this thread I found. Seems legit. Proven HP, via a crankcase vacuum.
He connected the crankcase breather to a 'T' fitting- and to each of the Pair valves. Actually not legal/against rules in most track riding.
 

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I see what you're trying to do. However, you have not done it.
If you think you have, dyno before and after.to really see any reproducible gains. Same dyno, same day.
Did you day what year you have? Sorry, missed it.

Check out this thread I found. Seems legit. Proven HP, via a crankcase vacuum.
He connected the crankcase breather to a 'T' fitting- and to each of the Pair valves. Actually not legal/against rules in most track riding.
Thanks for that I'll have a look I am concurrently wa8ting for a dyno run once they open I have paper work from previous runs too although not completely the same test parameters as on the same day run would have sould ar least give me a benchmarke figuer. I'm looking mainly for gains in torque rather than HP but I'm not sure if they go hand in hand i.e.

Mine is the k1 so not harness to modify!
 

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"don't cut wires if you remove it"
His K1 is the earlier design that is not connected to the ECM. Instead there's a hose to the throttle body that gets blocked off.

I'm dubious of Todd's gains and have had discussions with Beairsto Racing about it. He's tried a couple variants and didn't see any gains. He "would have sold a kidney for 5hp".

The automotive systems originally had a dedicated (and expensive) vacuum pump. Nowadays there are el cheapo versions where tubes run into the headers to produce the vacuum. This is very similar to what the PAIR system does and, like it, there isn't much vacuum. A problem with them is that if the engine blows, oil will run through the system, into the headers, and out onto the track. So they've been banned from road racing just like the motorcycle systems. But I gather they're still legal in drag and land speed racing. I've wondered if drag racers might be able to use a five gallon or so tank that was pre-evacuated and connected to the crankcase immediately before launch. On the Honda MotoGP engines, there are no ventilation holes between cylinders. Instead the individual cylinders are isolated from each other and the pressure built up on the downstroke pushes the piston as it rises. Good luck modifying your engine to do that.
 

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Lower pressure in the crankcase might pull oil out from the various journals and galleys but that might actually be a good thing. I've never heard of oiling problems associated with it. The good car systems with vacuum pumps run much higher vacuum levels than can be achieved with the PAIR system and I'm unaware of the need for different oiling with them.
Bit of a Hijack, but after pulling off my airbox last time, there was a lot of moisture in the sponge and hose of the crankcase breather
Sure a lot of moisture will disappear into the intake but not all (and water is less compressible than air), I figure some is actually getting pushed IN to the breather
 

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^That's moisture in the blowby. It works it's way up the breather hose and condenses in the cooler filter. There's a drain on the underside of the airbox where it will collect.
 

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^That's moisture in the blowby. It works it's way up the breather hose and condenses in the cooler filter. There's a drain on the underside of the airbox where it will collect.
With that doing the crank case breather mod could potentially put excessive amount of water in the engine. this wouldn't be such an issue on later model gixxers as pair is chanaled on the outside of the engine to the exhaust manifold just under the headers, but the early models the route is taken up through the cylinder head on the inside of the engine which would be a concern for me. Having oil crud build up in this area could bloke or corrode vital parts near the cylinders!
 
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