Partial DeSmog Question

[Sixgunluvr]

I saw a post on here somewhere about being able to remove the pair valve/put a hose where it was and be able to remove and cap the relative intakes?  Can someone elaborate if so as this step alone would save in fiddling with that whole piece of hardware that includes the T.

[John Schmidt]

I did a complete desmog without removing the PAIR valve ass'y at that time, removed them the next time I had the tank and airbox off.

I first removed all the rubber tubing, that left the "plugs" on top of the heads at each corner of the engine. I merely pulled those plugs, shortened the metal tube where the hoses had been removed, mixed up some JB Kwik and filled the metal tube...then placed the plugs back in place. On the underneath side of the heads is the place that needs to be capped off. Instead of doing that, I used my air driven hacksaw and cut the metal tubes near the top of the head and again filled with JB Kwik. Lastly, I capped off all the vacuum ports on the back of the intake runners, leaving #6 available for the petcock. About 50k miles later I sold that bike with that same setup still in place. Decided to leave good enough alone and only had the tank/airbox off once in that time which allowed me to remove the PAIR ass'y.

Basically, remove all the tubing and cap off where they were attached to the engine. Block off those spots with JB Kwik. Remove the PAIR ass'y. later.

[Sixgunluvr]

I was only looking to remove the pair valve and hoses/T to 3/4.  Nothing else if possible.

[Hook#3287]

While I haven't done or looked at the De-smog Process in decades, I seem to remember a hole in the air box that needs plugging.

[John Schmidt]

While I haven't done or looked at the De-smog Process in decades, I seem to remember a hole in the air box that needs plugging.

Yup...forgot that. What I did was sorta like a shortcut to desmog without removing the PAIR valve body until a more convenient time. The way I did it accomplished a total desmog and left that part in place but not hooked up to anything. Up here in Wisconsin, late fall or early spring it sometimes is a challenge to get the old bike up and running. So, I'd get my spray can of starting fluid and remove that cap on the bottom of the airbox that you mentioned, spray a bit of fluid in there and away she goes. Saves on the battery...and my patience. 

[Sixgunluvr]

I was only looking to remove the pair valve and hoses/T to 3/4.  Nothing else if possible.

Sooo…can I just get rid of the pair valve and the 3/4 T.  If so what exactly do I need to do?

[John Schmidt]

I'm not sure what you're referring to re. the 3/4 T.

[Sixgunluvr]

Referring to the hoses that go to carb intakes 3&4 and the pair valve all connected by a plastic T. And of course the pair valve itself.  I would be happy to just get rid of these alone and be able to cap them off if possible. I wouldn’t have to worry about replacing them which is impossible without taking the tank and air box off.  The line from #6 to petcock doesn’t bother me.

[Hook#3287]

http://www.valkyrieriders.com/shoptalk/desmog.htm

Looking at this write up from long, long ago, I realize I still have no idea how this system works or why.

Reintroducing gases to the airbox or some such foolishness', I guess.

It does seem there are 2 parts of it, one being #11
CONTROL VALVE ASSY., PULSE SECONDARY AIR INJECTION
18650-MZ0-671  and hoses attached to the "t" and carbs 3 + 4,

with the second being everything else.

Parts 1 + 2 are connected with the hose above the "t" to the top of #11

It appears the vacuum from carbs 3 + 4 operates #11, so if you remove the vacuum, the rest of the system seems just extra weight.  

I believe if you plug the carb intakes and the top of #11 you should isolate part 2, but I'm no engineer.

Good luck.

EDIT: On second thought, if you just remove the hoses on the 3 + 4 carb intakes and plug them, you should accomplice the same results.  Just a thought, as I said, I'm no Engineer.

[Joe333x]

Yup you can just remove the pair valve and cap off where the hose connections go and achieve the same result. That’s what I did rather can having to cut out the metal tubes on the engine itself.

[Sixgunluvr]

Thanks Joe! Now I’m getting some where.  I just need a little more detail.  So I remove the pair valve…I can cap off intakes 3&4.  What about the reed valve holes where the pair valve is plugged in?  And was one of these connected to the air box?

[Joe333x]

Same thing just cap them off, I had some rubber caps that fit on the air box.

[Sixgunluvr]

So I can just cap off these connections and do nothing else to disable the system and achieve my goal of eliminating the hose to intake nipples 3&4 correct? I personally like the looks of the air pipes. I mean they are chrome.




Anyone happen to know the inner diameter of the caps I would need for the two air control valve ports? I already have a plug for the air box port.

[John Schmidt]

If you remove all the hoses from where they are attached to the motor, there's no feed to the valve body itself so no need to cap it off. Just cap off where the hoses are attached to the engine, that leaves the PAIR valve body isolated and inert. That's why I said you can leave it where it is and remove it later when more convenient.

[Sixgunluvr]

Sorry for any confusion. The reason i asked about capping these specific connection points was because I only want to get rid of the pair valve and cap those 3 connection points and of course remove hoses 3&4 with T and cap those nipples.

Or…. Could I just leave the pair valve on and just cap the nipple on it ? This would save me from having to find caps for the pair valve connections. I would just need one cap for the nipple, then I could get rid of hoses #3&4 and cap them off?

[Jims99]

You can just cap the vacuum lines to the engine and ride that way. It will backfire a little when down shifting. If you remove the pair valve you can then block off the other ports and air box. I disconnected my airlines last year, I have the shiny desmog kit, just haven’t installed it yet. Capping off the metal pipes going to the engine will stop the backfire. Some will cut the lines off and fill pipe with JB weld.

[Sixgunluvr]

You can just cap the vacuum lines to the engine and ride that way. It will backfire a little when down shifting. If you remove the pair valve you can then block off the other ports and air box. I disconnected my airlines last year, I have the shiny desmog kit, just haven’t installed it yet. Capping off the metal pipes going to the engine will stop the backfire. Some will cut the lines off and fill pipe with JB weld.

Those vacuum lines are connected to the nipple on the pair valve. Wouldn’t capping that nipple take care of the backfire?

[Jims99]

The pair valve uses the vacuum to add air to the intake (I believe) to keep extra fuel from going in on deceleration. It won’t hurt anything, just isn’t as quiet as we’d like.

[Pluggy]

The PAIR system works after the engine has made power, so it does not "rob power".  Engine vacuum controls the PAIR system so the correct amount of fresh air goes into the exhaust system. 

On my bike, the #3 vacuum hose went brittle.  Desmog looked like a complicated way to fix a hose, so I replaced all three vacuum hoses.  RIDE ON!

See Page 1-36 of the Honda Shop Manual for a full explanation of how the PAIR system works. 

[indybobm]

I looked at this a number of years ago. If I remember correctly, the pair valve is activated in high vacuum situations. When you are accelerating, the vacuum is low and the pair valve is inactive. When you are decelerating, the vacuum is high and turns on the pair valve system. Fresh air is drawn form the air box, Through the reed valves  and into the exhaust system. Is it is exhaust pulses that draws the air past the reed valves.