PAIR removal works ! Thank you.

[ZA.Raptor]

A thousand thank-yous to the guys who have come before me and have posted about their experiences with removing the PAIR system to prevent backfires. I took the bike for a test ride this morning and its perfectly backfire free.

For the moment I have just blocked my PAIR system by the simple method of forcing a small (about 10mm diameter but thick enough to prevent air passing) thick piece of plastic I had lying around into the tube that runs between the airbox and the PAIR valve. Later on I will remove the whole system and make up 2 plates to close the little ports in the exhaust head. Ya know - make it a bit neater and a bit lighter

Interestingly, I first tried to disable the system by blocking the skinny vacuum reference tube, with no difference, so I suspect my PAIR valve might be leaking and allowing air into the exhaust when it shouldn't...

Thanks again guys, you helped me plenty.

[AZ]

Good to hear it,that`s a job on my list of things to do,which seems to be getting longer and longer .

[ZA.Raptor]

The good news is you can do the mod like I did (just blocking the tube) in like 15-20mins. Just remove the key guard (4 little allen bolts), remove the 2 bolts holding the tank and lift it up. Then the hard part - getting that weird Cagiva hose clamp off (I had to break mine off with a pair of pliers), then pull hose, shove something in there to block it, then everything else is "refitting is the reverse of removal" , as they say in the classics

If you want to completely remove the PAIR system (which I will do one day I promise ) I'm sure it will take a couple of hours...

Go for it dude - its well worth the effort.

[shedmonkey]

There are people on her who actually like the popping on overrun(no names mentioned) Now i would like a switch so i could do it when i wanted

[Hairy_Mark]

Surprised that you got back-firing with it on! You can't have standard cans.

What cans have you got?

The pair system burns unburnt fuel in the exhaust, cos the engines are run rich to meet noise emissions. With it working, secondary detonations can occur in the exhaust system, but standard cans with their three pass system kill the bang. Fit aftermarket cans to a standard raptor, with the PAIRS system working, it goes bang in the pipes and the sound goes clean out of the straight-through cans like a shotgun.

Disable the PAIRS and it's all quiet, but still running rich (and costing beer money).

A word of warning. If you ever need to re-build the bike with a new frame, like I did, re-install the PAIRS system or else you won't get the bike through the tests. Keep hold of the gear, just in case!

[ZA.Raptor]

Hey shedmonkey , you *could* put a valve into the tube that goes from the airbox to the pairs valve and have the popping on demand ... well sort of - you'd have to reach down to turn the valve - you do get small 1/2inch stopvalves for plumbing that close to open with a 90degree movement...

There are people on her who actually like the popping on overrun(no names mentioned) Now i would like a switch so i could do it when i wanted

[ZA.Raptor]

Hi Hairy_Mark, yes I've got a single (small) aftermarket can - the bike came that way. Hey in SA the roadworthy (as we call it) does not check for emmissions stuff so no worries

Is there any easy/cheap way to lean out the mixture a little ? (like soldering in a resistor or adjusting a POT or something ?)

Surprised that you got back-firing with it on! You can't have standard cans.
Disable the PAIRS and it's all quiet, but still running rich (and costing beer money).
A word of warning. If you ever need to re-build the bike with a new frame, like I did, re-install the PAIRS system or else you won't get the bike through the tests. Keep hold of the gear, just in case!

[pod]

Quote "The pair system burns unburnt fuel in the exhaust, cos the engines are run rich to meet noise emissions. With it working, secondary detonations can occur in the exhaust system, but standard cans with their three pass system kill the bang. Fit aftermarket cans to a standard raptor, with the PAIRS system working, it goes bang in the pipes and the sound goes clean out of the straight-through cans like a shotgun."

Not the way i understand it,
nothing to do with noise emissions, the PAIR valve opens when the throttle is closed , when the throttle is closed unburned fuel / over rich mixture passes into the exhaust and is burned off by the PAIR valve opening.
This is to lower CO NOX emissions by preventing unburned fuel passing right through the exhaust system..
I run std cans and the popping on the overrun caused by the PAIR was quite audible.
Its now removed. has been for a few years now. Never had any hassle at MOTs.

When the throttle is closed and the motor is on the overrun the high vac signal in the inlet causes the rich mixture, not enough air is getting through to give the right blend.