GY6 Pulse Air Injection...two examples.

[Bluefront]

Here are two examples of the PAIR emission systems on a Chinese 50 and a 150. They look a little different, but the operation is the same. They use the varying pressures in the exhaust system, to operate a valve which injects fresh air into the exhaust system, close to or on the cylinder head. This system does nothing to performance....it supposedly reduces emissions at the tail pipe. The first photo is the system off a GY6 50cc, the second is off a 150. There may be other PAIR systems on different scoots.....that look somewhat different. But they work in a similar manner. These systems are found on many newer Chinese scooters.





Using exhaust pulses, air is sucked in (yellow arrows). It is then blown through the hoses and exits at the red arrows, into the exhaust system. The blue arrows are for a vacuum line, necessary for the system operation.

The big problem with these systems, one that can cause melted hoses, exhaust noise, maybe even fires......a system failure. Should the valve fail somehow, instead of air being injected into the exhaust, the exhaust can then back-flow into the system, usually causing a hose to melt or blow up....the purple arrows. Hot exhaust gas is then exiting in the engine compartment.....causing a serious situation.

If you start hearing strange/loud noises from the carb area......check out the PAIR system, before something really nasty should occur.

[Eat Sleep Scooters]

When I disabled mine it back fired pretty bad when I let off. Is that normal?

[Bluefront]

Nope.....that system merely blows fresh air into the exhaust close to the engine. This supposedly tricks an emission sniffer device into thinking the engine is running "cleaner" than it actually is.

Backfiring when the PAIR system is disabled..... indication you have a carb jetting problem of some sort. IMO.

[swakk]

it s a trick but not to cheat
it s to provide fresh air to ensure that the unburned fuel will be "burned" in the catalyser
without the catalyser may be clogged quickly

for the schema
www.scooterchinois.fr/uploads/newbb/thumbs/1_4c76dc290f267.jpg

[Bluefront]

^^^^Actually.....the two PAIR systems shown in the first post were on scooters without a converter at all. Apparently they dilute the exhaust with fresh air. That way the sniffer thinks the exhaust is cleaner than it actually is...... something like that anyway.

[mainepeace]

My 2009 Peace Sports 50 has a TWC and the PAIR systems. TWC is the Three Way Catalytic Converter system.

And my PAIR system looks identical to the one in the first pic.

Greg

[dadzilla]

I was wondering what that abomination was...

[Bluefront]

Apparently......some scooters use an EGR system (exhaust gas recirculation). That system can look very similar to a PAIR system......but the operation is completely different. As an emission device, an EGR system actually works, and removing it can cause all sorts of running problems.

If you're unsure if you have an EGR or a PAIR system, post some pictures/questions. EGR systems can also fail.....but the chances of causing a fire are lessened, compared to a PAIR system.

[swakk]

abomination
for sure
by time, the system fail, and you finish with loud noise and hot exhaust gazs burning everything around

but, by removing it, you are outlaw, and , the catalytic converted will faill, clogged, so you will have a dead exhaust to change

[Bluefront]

^^^^^If you actually have a catalytic converter on your scoot, rather than a standard exhaust system, I wouldn't recommend any mods to any emission device, or to your carb either. Converters cost big bucks.

But.....none of the low-cost Chinese scoots I've ever seen, uses a converter. A fuel injected scooter might however. It definitely pays to consider the consequences before you start modifying your engine, and definitely find out all you can about the thing, before you start changing parts.

A catalytic converter on a small gas-engine scooter? That's the real abomination......

[swakk]

almost all have ONE catalytic convert inside the exhaust
even shipped in usa
some bigger bored than 50 cc have two inside
and worst some have 3, one in the exhaust pipe near the cylinder
the more you have, the worst your motor run
because they are expensive chineses use very little one, no more thant 3 cm diameter

[Bluefront]

"almost all have ONE catalytic convert inside the exhaust".....

Just where did you get that information? The photos I've seen of cut-up exhausts don't show one. The after-market exhausts don't mention one. The OEM manufacture specs don't talk about a converter, etc.

[earthman]

HEY BLUE

AS i KNOW YOU MUST UNDERSTAND, THESE POST LEAVE ME IN THE DARK.

i HAVE THE SYSTEM SHOWN IN YOUR SECOND PICTURE DOWN , HOW CAN I DEPOSE OF THIS JUNK

[Bluefront]

For sure don't dispose of it.....you may need to reinstall it down the road for legal reasons or for resale.



See the little black plate in the left corner of this photo.....has two nuts/studs holding it on? When you remove the PAIR system completely, this will be an open hole to the exhaust. You have to make a little steel plate to cover the hole. Some places will sell you one. There is also the intake hose to the air cleaner that needs to be blocked off, and one vacuum line that needs to be plugged.

These mods are for testing purposes only......I've been testing this mod on my Xingyue for about 8,000 miles now, with no problems.

[jimh]

My stock exhaust has a catalytic converter with all the tubing to recirculate unburned fuel in the muffler, that it has been removed and replaced with a performance pipe makes the point moot. As well, mine is Korean.