PAIR removal

Joe,

One more thing I forgot to ask, Did you have to have any extra
vacuum hose? I did not see that in your parts list...

S Lee

Ooo! Good question. I didn't order any vacuum hose because it's easy to find that pretty much anywhere. Thankfully, I didn't need any vacuum hose.

I just ordered the block off plates. On another forum I heard mention that removing the PAIR system will stop the popping my bike makes on decel from the pipes and may even assist the milage? Is this true?

Cheers,
Adam

93NJST said:

I just ordered the block off plates. On another forum I heard mention that removing the PAIR system will stop the popping my bike makes on decel from the pipes and may even assist the milage? Is this true?

Cheers,
Adam

Click to expand...

I didn't notice any change in mileage. However, it DID almost completely removing the popping on deceleration.

That is at least one positive thing. What happens to that extra fuel if it is not being burned off anymore? Thats what I was told the poping was from.

Cheers,
Adam

I'm not certain about that. I know that if my mileage changed at all, it was a VERY slight amount. Changing the Clearview on my bike for a stock screen produced a MUCH larger mileage difference.

From what I've been told, the purpose of the PAIR system is to add clean air to the exhaust flow in an effort to "dilute" the exhaust. But I'm no expert and I may certainly have misunderstood.

I decided against the do it yourself approach. The dealer Diagnosed and determined the backfiring was coming from extra air added back via PAIR system and then 4 weeks later they have added the plates I ordered via Muzzys. I used Curmedgeons suggestion for ordering and appreciate that and the general information he provided.

I think parts and profesional labor added up to $150, but my pipes are still in place, the plates were sandwiched between the air return pipes and the the the engine, They said removal would be 5 more hours labor, which is aT LEAST $400. nOW IF i WORKED ON PEOPLE'S HOUSES THIS WAY LEAVING THE OLD JUNK BEHIND, COULD i CHARGE $80/hOUR?

MARTIN G.

I don't see how the mileage could be improved by removing the pair system. The popping is caused by unburned fuel being ignited in the exhaust system. To get any improvement in mileage you'd have to more efficiently burn the fuel in the cylinder not the exhaust. Unless of course you think it might work like a fighter jet and use the fuel burning in the exhaust like an afterburner.

Phil

The PAIR system simply inserts clean air and fluffs up the exhaust to make it seem more clean coming out of the tail pipe for emissions testing.

I plan to pit on the block off plates today. We will see if it makes any improvement. I just can not seam to get rid of the idle flux on my ST.
I also want to replace the fuel lines, does anyone know what size I need to get?

Cheers,
Adam

Awesome information !

GetaHandleOnit said:

Awesome information !

Click to expand...

Uh... Rob, you might want to read this thread of the same name for a little more info on this subject:

https://www.st-owners.com/forums/showthread.php?t=31915

John

DaveyB said:

I can clearly see why removing the PAIRS system would increase both power and MPG.

Click to expand...

Interesting rationalization for removing yours, Dave, but you need to consult your Honda ST1100 Service Manual, page 1-33, and see how it actually works. There's no loss of power and no decrease in fuel mileage with a properly functioning secondary air supply system. It just "changes a considerable amount of hydrocarbons and carbon monoxide into relatively harmless carbon dioxide and water vapor." It's a passive system, the intake vacuum only getting involved when you roll off the throttle quickly, causing high vacuum which then closes the valve, cutting off filtered air from the air cleaner to the exhaust manifold (reduce afterburn/'decel-pop').

Regards, John

Factory Pro probably removes PAIRs because working around them as much as they would need to in order to dyno-tune a motorcycle (carbs have to come off multiple times, generally) is a royal pain in the butt. If you're the guy doing the work, removing the valves and associated plumbing is therefore of immense, immediate benefit.

Accordingly, and as most motorcycles are actually ridden very little, any minor environmental benefit from retaining the system is very likely outweighed by the inconvenience of having to work around (and maintain, and possibly repair) the PAIR system. However, the cost-benefit analysis can always be rejected as not addressing the moral issues related to the causes of pollution and us "all doing our part" (even if it is statistically insignificant) in reducing it. (Obviously, a bigger part would have us all using public transport and not riding obscenely individualistic motorcycles at all.) Unfortunately, this is the kind of issue where there will always be disagreements. Witness the endlessly predictable heated discussions re loud pipes, helmets and (dare I say it) bright lights...

Ciao,

Not to beat a dead horse about another rationalization for pulling the PAIR on ST1100s, but what PITA/inconvenience while pulling carbs...?



The carbs are out. See any PAIR stuff in the way? There's just the one PAIR hose to hook up at the front of the carbs body (not shown sticking up through the mat here in this picture as I left it attached to the carbs instead that time) when R&R'g the carbs. Why on earth would the valves have to be removed during a 'dyno-tune'??

And how often do the PAIRs fail? Hardly ever, IMNSHO. They're a passive, pretty much bullet-proof system.

Look, if you want to pull the PAIRs, just do it.

FWIW, John

Fair point. I don't have an ST1100, so I was speaking in general terms (and reading into Factory Pro's bald statement about them). Perhaps the orientation of the ST's V4 engine is better suited to PAIR plumbing, but I can assure you that the same is not the case with Honda's other V4s. I don't think the system makes much of a difference to perfomance or the environment, so leaving it or removing it is really best left up to whoever is inclined to do the work to remove it, or work around it, as necessary.

TBH, if I'm not working on the engine, I leave it in place. But, one of my VFRs has had so much engine work done, there is no way leaving it in place would have made sense. Another bike has a supercharger kit installed, which necessitated the removal of the PAIR system entirely (it was engineered to work without it), and some of the others have had their engines out and re-bored, so blocking off the PAIR and vacuum ports made more sense than attempting to re-install the spaghetti-like componentry. FWIW, assuming the PO hasn't already removed it from my ST1300 (I've never noticed), I have no intention of removing it from that bike--unless and until I start doing work on the engine.

Ciao,

Hi Joe, I'm unable to bring up the site where you received the PAIR write up. I wonder if you would be able to locate the printout and email it to me. If your unable to locate it or unable to do it that's fine. Thank you, Neil New owner of a ST 1100, 2000, 15000 miles. neilrupp@metalink.net. I'm working on the carbs at this time. Thanks again!

Neil. This thread is 5 years old. "Joe" hasn't been on the forum in a year. MY-MC.com died but was resurrected as my-mc-phoenix.com; however, there is an archive of the old data but I haven't used the search function so don't know how hard it would be find what you may be looking for. If your secondary air supply system is working, why bother to remove it...?

John

I've been around ST1100 forums for almost 20 years and this still gives me a chuckle.

If you got the time and the money, go ahead. I'd rather be riding than wrenching and using the money for gas.

I'm pretty sure it is illegal. But, I doubt anyone would know in a non-inspection state. I doubt if more than a few would know in an inspection state.

Just for discussion sake... Does the ST1300 also have a pair valve system? I know that both my VTX 1300 which is carbuerated and my VTX1800 which is fuel injected have the pair systems. I guess I never really dug into an ST1300 enough to think about it. The ST1300 already runs so powerful, smooth, and thrifty. I don't want to disturb it

Also for discussion sake I can't believe all the differing ideas as to what it is there for on the engine. Per my reading other sources years ago the function is to allow air into the exhaust right after exhaust valve to facilitate final ignition for any unburned fuel vapor that may be escaping the motor when you let off the throttle, thereby helping emmissions. That's where the popping can come from during deceleration. The increased vacuum when you close the throttle opens the reed valves allowing all this to take place. It's been a few years since I read all about it. Sounded similar or like a fancy EGR system found on automobiles. Did I read all of this wrong? Removing it from my VTX twin machines offered a little less popping during deceleration and cleaned up the top of the motor a great deal, but it offered no difference in fuel mileage or performance. It was simply less "stuff" to troubleshoot. The cover plates are still available for those machines at many sources.