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I always love to read postings like CBR Nomad's.
The bike needed a new piston and rings at 16K miles. "I always use fully synthetic oil".
Don't you mean "fully pathetic oil"?

Rick
 

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soluble comes from origins of 'solve' [a puzzle, break it up etc]
(english 'u' a later inclusion than original letter 'v' - and double uu or w)
so soluble means able to be solved, or dissolved, for things
[eg sugar in water]..

in- here the latin origin prefix meaning 'un-' as in not..
not soluble or insoluble.. not solvable or doesnt dissolve..

depends on origins of particular words, prefixes etc
esp latin, old english, french, germanic etc
and the various offshoots of them all,
plus pronunciations favouring this or that
spelling..

ive had to 'translate' [based on being australian]
between broad scots, southern usa, liverpudlian [uk etc]
servicemen on leave who couldnt understand
each others 'english'...

curious what folk see as 'normal' [or not]
in that same situation an islander in our navy
was about to literally kill a usa serviceman
who greeted him with a friendly "hey mutherfukker!"

one black usa bloke thinking he was being friendly
to another black bloke whose idea of ....ing his mother
was the height of deep personal insult..
our island guy would have bitten his throat out
[literally] if we hadnt restrained him and explain
that the nice yank bloke was sending a friendly
greeting for his mother.. big island smile..
everyone mates again..
words...
 

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soluble comes from origins of 'solve' [a puzzle, break it up etc]
(english 'u' a later inclusion than original letter 'v' - and double uu or w)
so soluble means able to be solved, or dissolved, for things
[eg sugar in water]..

in- here the latin origin prefix meaning 'un-' as in not..
not soluble or insoluble.. not solvable or doesnt dissolve..

depends on origins of particular words, prefixes etc
esp latin, old english, french, germanic etc
and the various offshoots of them all,
plus pronunciations favouring this or that
spelling..

ive had to 'translate' [based on being australian]
between broad scots, southern usa, liverpudlian [uk etc]
servicemen on leave who couldnt understand
each others 'english'...

curious what folk see as 'normal' [or not]
in that same situation an islander in our navy
was about to literally kill a usa serviceman
who greeted him with a friendly "hey mutherfukker!"

one black usa bloke thinking he was being friendly
to another black bloke whose idea of ....ing his mother
was the height of deep personal insult..
our island guy would have bitten his throat out
[literally] if we hadnt restrained him and explain
that the nice yank bloke was sending a friendly
greeting for his mother.. big island smile..
everyone mates again..
words...
You are a cunning linguist.
 

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juzman - mate how did you go about
restricting your pair valve ?

thanks :)
I just cut about 15mm off the end of an old toothbrush, was a round Colgate one. Fitted in tight, put hose back on pair valve then secured with the little clamp.

Sent from Motorcycle.com Free App
 

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removing pair valve system

juzman - mate how did you go about
restricting your pair valve ?

thanks :)
I realize this is getting off topic and should be posted in a more appropriate area but the interest seems to be here at the moment.

By having an aftermarket exhaust and no catalytic converter you get much more backfiring ( and with a little practice blue flames can be made to come out of the exhaust on a dark night). All of which burns out the muffler packing way too soon. It can almost all be eliminated by removing the pair valve system.

The most effective way is to use a smog block off plate. They are available on ebay for every motorcycle you can think of (almost) except for the cbr250r until now (Graves Motorsports offers one for our bikes). See pic 1

I installed a plate a year ago but had to make it myself. See pic 2

By installing the plate you can remove the pair valve itself, the air line and servo valve going all the way back to the air box. There is an electric connector on the servo valve that has to be disconnected, which tells the valve when to open and close but will not trigger a fault light to come on if disconnected. Push a vacuum line cap on the air box fitting and you are good to go. See pic 3

It doesn't take that long to do if you don't have to make your own cover plate and it removes a lot of engine clutter plus some extra weight reduction. The big plus is that nothing is damaged and all the parts are there if you wanted to ever return the bike to stock condition.
 

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gromit - thanks for that specific info.. i'd found references to 'smog plates'
elsewhere [cbr600rr forum etc] but hadnt found any links for cbr250r..

going for 'efficiency' generally with my lv slip-on, so prefer to not have
oxygen injected into exhaust flow close to exhaust port creating extra
heat for the sake of sensitive cat which is no longer there..
some hold the view that this also may interfere with
exhaust pressure and backpressure thus potential
efficient combustion chamber fill and clearance etc..

i like handyman fixes for problems generally
as manifestations of mind at work, but still
theres a certain attraction to a nicely
engineered solution as well..

my lv eu approved slip-on incidentally has ok backpressure
with both restrictors in but still lets out one or two small
'farts' now and then throttling off in say second gear..

i didnt mind but black beauty may have been embarrassed,
so thanks all for your excellent and handy advices...
 

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This might be a stupid question, but couldn't you skip buying the block off plate and just put another vacuum cap on that end, too? Then you'd be able to remove the valve, still.
 

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This might be a stupid question, but couldn't you skip buying the block off plate and just put another vacuum cap on that end, too? Then you'd be able to remove the valve, still.
Never mind. That wasa dumb question. I didn't realize before that the valve was the silver piece and the black piece was the servo. Went back and re-read it and went, "Doh!".

So, you wouldn't be removing the valve but you could still cap off each end and remove the servo. I'm just not sure there's any benefit in removing the valve to justify spending over $20 on a block off plate.
 

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I'm just not sure there's any benefit in removing the valve to justify spending over $20 on a block off plate.
Since I have no intention of removing my stock muffler or CAT, I guess this is a moot thread for me to be reading, but I am facinated by this removal process.

But I would have to spend the $20, because I could never create anything as nice as your block-off plate.

 

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Never mind. That wasa dumb question. I didn't realize before that the valve was the silver piece and the black piece was the servo. Went back and re-read it and went, "Doh!".

So, you wouldn't be removing the valve but you could still cap off each end and remove the servo. I'm just not sure there's any benefit in removing the valve to justify spending over $20 on a block off plate.
Not a stupid question at all. What you suggest would work fine. The only problem might be with a slip on vacuum cap is that they are not very heavy duty and they might not hold up to the heat from the cylinder head area very well.

Most bikes are multi cylinder and have up to 4 pair valves and a real rats nest of plumbing hoses and connectors to deal with. $20 for one plate is high (usually you get two plates for less than $20). That was the first plate I have seen offered for the cbr250r and it is overpriced.

Getting all the way back to this threads topic of finding the dreaded engine rattle. If you take off the silver air intake for the pair valve you will find the actual pair valve and a diffuser plate under it. Both just drop in and sometimes the diffuser plate is actually loose. Some multi cylinder bikes are very noisy and quiet down when the pair valves and diffuser plates are removed. A single cylinder engine vibrates by its very nature and after I removed my pair valve and diffuser plate it did quiet down. Not saying that is cure for the engine rattle but it could be one of them for some people.

See pic for what is under the pair valve inlet cover.
 

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An additional note to my last post. The pair valve itself is surrounded in a black rubber frame that acts as a reusable gasket and seals very well. You can remove the diffuser plate below it if it seems loose but reuse the pair valve instead of trying to make a gasket.
 

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Until now I had never heard the term "pair valve".

Is this a system to inject air into the exhaust just downstream of the exhaust valve?

I knew of a system like I just described that was introduced to the BMW twins in 1980 ('81?) in an attempt to make the bikes appear to be cleaner burning to the exhaust sniffers.
Most folks just removed all of this unsightly and heavy plumbing and blocked off the source and the port near the exhaust. It had nothing to do with modified exhaust systems, and of course, back then, there were no catalytic converters.

But if my bike would benefit from the loss of these parts, I'll do it. I'll even pony up the $20 for the block-off plate, unless someone on the forum with a machine shop would like to turn them out for us at a better price.
 

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Until now I had never heard the term "pair valve".

Is this a system to inject air into the exhaust just downstream of the exhaust valve?

I knew of a system like I just described that was introduced to the BMW twins in 1980 ('81?) in an attempt to make the bikes appear to be cleaner burning to the exhaust sniffers.
Most folks just removed all of this unsightly and heavy plumbing and blocked off the source and the port near the exhaust. It had nothing to do with modified exhaust systems, and of course, back then, there were no catalytic converters.

But if my bike would benefit from the loss of these parts, I'll do it. I'll even pony up the $20 for the block-off plate, unless someone on the forum with a machine shop would like to turn them out for us at a better price.
Your description of the system is perfect that is exactly how it works. With fuel injection, catalytic converter, o2 sensor, temp sensor and ecu / ecm, the system only activates at the rpm ranges that coincide with the ranges that pollution testing devices use (surprise surprise).

There is NO performance gain or loss if it left on or removed. The only real reason to remove it would be if you had a race only bike and dyno tested it on a regular basis because it would give an incorrect result because of extra air. That can fixed by just clamping the air line shut to the pair valve during a dyno test.
 

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There is NO performance gain or loss if it left on or removed. The only real reason to remove it would be if you had a race only bike and dyno tested it on a regular basis because it would give an incorrect result because of extra air. That can fixed by just clamping the air line shut to the pair valve during a dyno test.
I can see what youre saying about it throwing off the AFR readings, but Im curious how it stops the popping and why its recommended to remove it when installing an aftermarket exhaust/fuel controller if there are no performance gains. Not trying to be argumentative or anything like that. I am genuinely curious, is all.

Thanks for the great info on this subject! Maybe we could take the posts about the PAIR valve out of this thread to keep it on subject and create a stickied thread for discussing the PAIR system?

Admins? Yay/Nay?
 
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