Egr stuff, I think...

[ratdog]

the first bike I worked on had the EGR system I see all over online.  That’s with the chrome loop above the valve cover and down line junk.  When we installed the BBK, we got rid of it.  Before we junked the EGR stuff, the bike had a terrible time on first startup.   You had to let it idle for way too long before you could even open the throttle.  I hate that because while that engine is at idle, it’s getting very little oil.  Very bad if you go to a BBK.  Anyway, after we junked the EGR stuff, it was much better and could accept throttle right from the start

so on to the bike I’m working on now.  It is really bad on first startup.  But it dosent have the EGR head.  Instead it has some funny thing on the exaust pipe that looks like it might have a reed valve and goes to a bunch other stuff and houses.  I’m thinking this is some sort of EGR that I’m not aware of.  Does everyone anyone have this and have you bypassed it?

[GrumpyUnk]

I have seen multiple setups to handle 'emissions'. Most are disconnected or have hoses flopping in the breeze.

To know what does what, you have to follow the hoses/lines that are connected to the device in question.

EGR is exhaust gas recirculation. It feeds a small amount of exhaust gas back into the intake stream, the gas being composed of 'burned' components cannot regularly burn as fuel and air, so is somewhat 'inert' as far as contributing to combustion. That inert gas effectively dilutes the fuel:air mix so it will burn at a lower peak temperature, and reduce the formation of NOx - nitrous oxides - in the exhaust. To have EGR, you have to pipe the exhaust gast back around to the intake manifold somehow. If you have true EGR, you may get pinging if you remove it.
I have followed the hoses around on the several machines I have, and still don't see one that does EGR. I do not know what the PAIR system does, but it seems to pipe exhaust gas at the left side up around and over the the exhaust port on the cylinder head. I just doan geddit...
tom

[jeff84]

pair systems allow fresh air to mixed with the exhaust gasses. this fresh air provides o2 so the unburnt fuel can ignite in the exhaust pipe. its why removing it with a stock pipe tends to clog them up, and leaving it in place with an after market pipe causes a lot of popping out of the pipe.

[ratdog]

This is what I’m talking about. I think after we get a few hours on the engine I will try just blocking it off and see what effect it has. If it run as well or better with it blocked off, ther is a bunch of crap I can pitch and some hoses I can seal off.

I have a lot of experience building engines, but almost never did anything with pollution crap. When your building racing engines, all that stuff is long gone, so I’m a babe in the woods on this

[jeff84]

that is a pair valve. I have never seen one directly on the exhaust before, usually its on the head.

[GrumpyUnk]

I have examples of both. It seems the one shown above that is directly connected to the exhaust pipe is an older design. The PAIR system seems to have reduced the parts & hose count. I don't see it doing anything evil or causing any problem if left connected.
I have yet to see an actual EGR system, but maybe I have not figured it out yet. There is a LOT of diversity in the systems used. Some have a vapor recovery system and others do not. There seems to be no rhyme or reason as to what is installed or not. My general reaction is to leave them alone as they are.
I think PAIR stands for Pulse Air Injection Rmumble. I think it uses exhaust pulses to push extra air into the ehxhaust pore. Maybe not exhaust pulses but crankcase pulses given where it is connected to the valve cover and there is a 'flapper valve' embedded into the cover. As the piston moves, low and hi pressure pulses are formed in the crankcase. Apparently they are being taken advantage of to pump some air...
tom

[jeff84]

I would just leave it, unless you are going to run an aftermarket pipe, in whichcase it would be removed anyway because it is on the pipe

[Moat]

GrumpyUnk and Jeff are right on the money; these are PAIR air injection systems - not EGR (AFAIK no scooters/motorcycles use true EGR) - and have virtually no effect on performance (aside from any leaky vacuum lines that may be associated with it). Removal saves a little weight and clutter... but that's about it. Exhaust fumes will be dirtier and possibly it'll cause increased afterburn/popping on deceleration.

Bob

[kagetenshi]

Most of the egr/pair system crap that are on scooters here in the US are imported with it to appease the California epa regulations. Unless where you live requires inspections in order to get it registered, I say remove it. It equals less possibility for vacuum loss.

[AtariGuy]

My 2t (06 venice) had one built into the exhaust header similar to that - and would dump some exhaust gasses through a carbon filter to reduce dirty emissions. It had a vacuum line tied to the manifold that would pop the valve open while running to do its magic, but found a few cracks in the vacuum line which would suck fresh air into my AF mixture causing a lean run.

Personally, i'd go about removing the emissions garbage in any case and plugging the exhaust bung just for peace of mind.

Plus side tho - if you decide to install a wideband, you have a great location to begin

[ratdog]

I wish I were serious enough to do an O2 sensor. It would be fun to test all this stuff with real instruments. But, I have real bikes to play with. My 600 is running in the tens when I drive it to the strip, and in the low tens when I set it up for drag racing and put it on the trailer to go to the strip. I’m thinking it would be way cool to have a 600 in the nines! And I’m always looking to make Who’s chicken Too, faster, even though there is seldom anyone to race me (locally). I’m not a fan of bracket racing. I want every run to be faster then the last! ( yeah, I know, good luck with that)

Biggest change is I now have my adult son living with me. He is lighter and has better reaction times. So the old man has been teaching him.