PAIR problems again??
 

Some of you might remember the first time I posted. I had flipped the reed-stoppers around on the PAIR valves and bolted everything back up as-is, and had major problems.

Well, I figured I had something going on with the stoppers, so I just put on some blockoff plates. Well, I have the SAME problems. I have checked for leaks on both of the plates and they are sealed up tight. I also removed the original housing, and both tubes going to that valve, and capped the valve off.

Here's my problem. The bike fires up and idles fine, and also free-revs without intake or exhaust backfires or pops. But as soon as I put the engine under load and start accelerating, I get VERY LOUD clacking sounds, very similar to the sound the carb slides make on decel, but this is a very loud and violent clack, that is through the entire rpm band. Also the motor has severe hesitation, extremely poor throttle response, and ZERO power.

This has happened twice now, both times in attempts to disable the PAIR system. I've triple-checked my work and can't find anything wrong. Is there anything I could have overlooked? Thanks guys.

Hmmmm
 

Hey Brooks;

I'm thinking that there is something else that has happened. Some questions;
Was the bike..is the bike running fine with no modification on the PAIR system?? I'm thinking that you have got some hoses off.. or mixed up. The hoses that run up into air box from the carb bodies...Kind of providing chambers for the constant velocity..have you got those right?? Have you got a manual? Walk through all your lines...The pair system is down stream from anything to do with performance so even if you don't have them properly set it would not make it run badly..just lots of backfires. Have you done anything to the airbox...baffles any of that sort of thing??
..Keep posting info..togther theres lot's of skill on this site..

Take Care
Dave:D

The bike runs BEAUTIFULLY before I mess with PAIR. It pops a fair bit on decel, always has, but it's never affected performance and it pulls HARD, it's very tricky keeping the front tire down.

The airbox snorkel has been removed, that's the only modification. When I bought the bike, it was wrecked several times and taken apart and put back together, not 100% correctly, by the previous owner. The long carb trumpet was on the front instead of the rear and a screw was stripped.....I keep finding the guy's mistakes.

I have a manual but it doesn't go into great detail of the PAIR system. If someone has a diagram of the system, from the airbox to the valves, it'd be great.

The bike runs BEAUTIFULLY, until I disable the two valves on the cylinder heads, and the second I do that, it begins clacking horribly and pulls as if it's only running on a single cylinder. It's THAT bad.

More HHmmmm
 

Hey Brooks;
The clacking can be because you have messed up putting the PAIR valves in wrong...If that is so..You could be pulling exhaust gas back up and into the airbox...Do you have the lines completely blocked off from the pair system?
A common screw up with the VTR is to get the hoses mixed up of left off.. So I would start with a real look at that...Start with the vacum line to the petcock...it's not the bottom but the back...Then work all through all airbox lines....I'd put the snorkle back in if you have it...Did you do the PAIR mod along with anything else..ie; snorkle removal or k@n filter???

Dave:D

I installed the PAIR valves the way they came out... The blockoff plates prevent any airbox contamination, there's no exhaust gas getting back there.

None of the mods were done at the same time as disabling PAIR. The bike was tuned with the snorkel out and the tuner was able to do an awesome job with the Factory Pro kit, and I sacrifice very little in the way of useable power.

From the valves back.....the valves are in, reed-stops in place just how they came out, and both rubber gaskets are good and seated. The blockoff plates are tight and not leaking. The hoses and OE pair valve housings are off. At the check valve, on the passenger side by the airbox, both hose inlets are blocked off. That's as far as I got.

This is quite a mystery. The only thing I can think of is that you've got extra air coming into the airbox somehow, and it's making you run lean. You're saying everything is plugged up and sealed off when the block-off plates are on?

Correct.

And the last time I disabled PAIR, simply by flipping the reed-stops and that's all, it's had the exact same result. Terrible clacking/clattering noises, zero power, zero throttle response.

I'm chalking it up to supernatural forces, and challenge anyone to prove me wrong. Now bust out the Tarot cards, or do a seance or something. Or perhaps there's a spell somewhere that would unravel this bound up negative energy surrounding your PAIR mod. Hm.. Have you tried meditating on it?

I quit, this is the last time I modify this bike I swear!

PAIR problems
 

Hey Brooks..
I hear the frustration...factories work hard to make things work...so our changes can bite us. But disabling PAIR should not screw up your performance. Bear with us...questions
1: When you put the PAIR back to stock does it run fine???
2: Did the "clacking" stop when you put in block off plates??
3: Have you carefully checked all your hoses??
4: Have you looked in the airbox...does it look normal in there??
If the poor performance persists with PAIR blocked off correctly or returned to stock and all your hoses are right..then something has happened to carbs. during the run up you did that may have allowed exhaust gas to come backwards..seems unlikely...
I know this is driving you nuts..but I'm still guessing you have gotten some hose pinched or on the wrong spot....Are there any other "experts" that can respond..please no more vodoo sh..Anybody live near this guy...

Keep talking to us..
Dave:D

Dave:

#1- Yes, when I connect PAIR back up the bike runs fine. At least it did last time, I haven't had the time to reconnect it again. I will do that within the next day and repost the effect.
#2- The clacking noise was present both when I flipped the reed stops to disable it the first time, and then the second time when I just installed the blockoff plates. It's a loud noise, very similar to the carb-slide noise, and happens constantly, in a violent fashion, during acceleration or load. I can't notice a distinct noise at idle or on a free-rev but as soon as I jump on the bike, I know something's very wrong.

#3- I've gone through the hoses and cannot find any that I missed blocking off. I only removed the two hoses leading to both pair valves, and capped off both fittings on that check valve or whatever it is, on the right side of the airbox.
#4- So far as I can tell, everything seems to be normal in the airbox. I'm stuck at work all day today but I have the weekend off which should give me ample time to find out what the hell is going on.

I tried to go through all the lines in more detail last night, but working with the halogen lamp on at 10 pm in a closed garage gets pretty tedious and sweaty. Not to mention I'm a mechanic by trade and had just worked a busy 11-8 shift, coming home to put in another 2 sweaty hours isn't my idea of a break.

"that check valve or whatever it is, on the right side of the airbox."

remove it also and cap all the lines going to it.

the problem is the line to the carbs from this.

that lil check valve thing yur talking about needs completly removed and all the lines going to it need plugged... theres a more gracefull way of doing away with it and all the tubing up in there but just plugging all the lines will work.

i can post a pick tonight of all the stuff u can remove when doing away with the pair stuff. that will give u an idea of what needs capped and what u might be missing. if you want me too?

=Removed all of that crap, don't just block the lines off.

I installed the TBR block off plates, removed everything PAIR related including all hoses and blocked off the air box holes, Simple to do. Configure the head block off plates to stop the flow as you did before, remove all the hoses from the vpair valve to the air box, go to Autoparts store and buy two rubber caps to cover the holes left in the air box where you pulled off the thumb size air lines, block off the small vacume house that activateed the PAIR valve.

i removed all the tubing and everything too, but i can see where it might get complicated. theres a bit of a maze of plumbing down there. i just used VTR silcone on the airbox and stuff. the tub going to the carb i removed the T completly and doubled it back on itself. i even gutted the carb coolant stuff while i was in there...

I agree with Zedicus....TAKE IT ALL OFF AND Plug the Air Box hole and the line to the Carbs with a screw in the hose. And you will be all good.

I took all the stuff I took off and put it all back together and stuck it on the work bench for decoration.

I actually did it just like Thumper....clean job! Well said Thumper!

Clacking Sound
 

Hey Brooks;

This clacking sound....other than real internal engine damage...carb slides...perhaps something is going on with the CV carbs??? some vacum issue.. Perhaps it's deeper...might have to check your cam timing...cct's okay?? Wade in guys.. let's help this guy....

Keep talking we will all learn from this
Dave:D

Hey guys, could the clacking noise be coming fro the PAIR valve itself? As its not able to operate as it normally would?

I'm thinking they are on to something. If you have the actual PAIR valve on the airbox with open holes, that could be your problem. I wouldn't count on that staying closed with the intake pulses and whatnot. If you're saying that everything was closed up, but didn't include that, that's what I'd be looking to seal off.

This is what I think it might be. Sometimes we get so focused on one train of thought (i.e, the last thing we changed), that we don't think about other, possibly totally unrelated, things.

Remove the air cleaner and velocity stacks. Look at the two slides. Are they in the same at rest position? If not, one is stuck. If both are correct, try pushing them both up and then releasing at the same time. If one is slower, it's probably sticking when under load.

On the pair issue, I simply placed a rubber cork in the inlet there at the valve cover and reinstalled the hose over it. Cheap, easy, and effective.

I agree, put the PAIR back to stock, let us know if it runs 100% again.

I'll dig into it tomorrow guys, all the parts stores are closed tonight and I managed to put a nice slice in one of the old PAIR hoses getting it out from behind the frame....

The control valve, the two tubes are plugged, but not with caps (again, auto parts stores closed....working all afternoon and getting off late makes it an SOB to get parts)...they're half-ass plugged with short pieces of hose, screws and a little wooden nut-cover I had in a drawer. Perhaps they're not sealing 100%. I know, I know, flame on....but what can ya do when you're working on things at 11 at night, my garage isn't quite the junkyard I wish it was....I can only cannibalize so many old parts

As far as engine/valvetrain damage or carb malfunctions, this problem has only happened when I have tried to disable the PAIR system, as afore mentioned.

I checked the control valve out and it appears the hoses are run correctly. I'll let you guys know more tomorrow afternoon when I can devote a few hours to it.

All the input is appreciated, you guys are the best!

I've a question for you. Are both gaskets on both PAIR valves. It sounds to me like the PAIR valve is rattling around when you give it power, like it's loose inside its housing. Check that.

Well I removed the entire control valve today, capped off the inlet at the airbox, and plugged the vacuum line from the carb....was going to cap that too but I didn't want to remove the airbox. I was able to remove the control valve and all the plumbing and everything except that small line, by just propping the tank up on its end and removing the airbox cover.

She runs like a champ again! No more PAIR-related popping, only now it's showing me my tune isnt as good as I thought it was :lol: But it runs great so I'm not messing with it. Maybe a flo commander down the road.


Thanks so much for all the help, you guys kick ass. I'd buy you all beer, but I get a feeling it's against the law to ship cases

Hi All
I have a quick question somewhat relating to this. Will the blocks off plates for a RC51 work on are bikes?

I believe they do...but don't quote me on that. Just make yourself some....it's easy to do. get some 1/8in plate alum. and trace out your old pair valves and remove the pair tubing. Or go to Greg's "Hawkrider" site for detailed write-up. Or click on the link below.

Hope this helps!

https://www.superhawkforum.com/forum...ead.php?t=3971

Thanks!!!

It's probably something simple! Undo the mod.