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De-PAIRed SH that used to run great

Old 09-25-2010, 05:55 PM
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De-PAIRed SH that used to run great

So over the past few months I have been working on my SH and finally got it running well. Replaced plugs, filters (stock), cleaned carbs and set needles (dynojet), and de-paired. The bike has ran great for the past 5 weeks or so and now it it is starting to run progressively worse. Backfire on decel, worse than it used to before the pair removal, not idling at a steady rpm and the occasional carb fart. I am thinking that the carbs are dirty again, but before I rip them apart, I thought I would ask if anyone else had this problem. I bought the PAIR plates off of ebay and I flipped the reed around and put the plate over top. Could I have air leaking in by the plates?
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Old 09-25-2010, 06:33 PM
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If there was an issue with the PAIR plates you would have exhaust leaking out, not air leaking in.


Rex
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Old 09-25-2010, 07:42 PM
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Sounds like a possible vacuum leak. I'd check that out first
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Old 10-08-2010, 01:44 PM
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Where is a common place for a vac leak on the SH
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Old 10-08-2010, 02:22 PM
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In a hose... And no, I'm not making fun of you...
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Old 10-08-2010, 02:50 PM
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The PAIR can't affect performance, so you've got something else going on.
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Old 10-08-2010, 05:33 PM
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Originally Posted by Tweety View Post
In a hose... And no, I'm not making fun of you...
There's not many posts that make me spontaneously laugh. Thanks!

My latest was an exhaust donut that was blown and it was leaking fresh air into the mids before the cans. On decel they were blowing 18" flames. Put in new donuts and it totally went away.
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Old 10-08-2010, 07:05 PM
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PVLIR?
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Old 10-09-2010, 07:51 AM
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So is the pair valve like a PCV valve on cars?
Cause my rear one was sucking in air bad.
I capped it off now it's running funny like weaker.
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Old 10-09-2010, 08:16 AM
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The PAIR is for injecting oxygenated air into the exhaust gasses to reduce emissions by igniting unburnt fuel, making it impossible to get reliable data on a dyno or wideband... In stock form it makes for backfiring, and makes it hard to get a decent setup, but unless you change stuff, a leak into the exhaust in this way should not affect performance in any significant way... The setup you have isn't affected...

You really should lift those caps and check that the reed valves are inversed if it was sucking in air...
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Old 10-09-2010, 10:02 AM
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Originally Posted by Tweety View Post
The PAIR is for injecting oxygenated air into the exhaust gasses to reduce emissions by igniting unburnt fuel, making it impossible to get reliable data on a dyno or wideband... In stock form it makes for backfiring, and makes it hard to get a decent setup, but unless you change stuff, a leak into the exhaust in this way should not affect performance in any significant way... The setup you have isn't affected...

You really should lift those caps and check that the reed valves are inversed if it was sucking in air...
So from stock they should be sucking in air?
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Old 10-09-2010, 10:17 AM
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Originally Posted by lazn View Post
PVLIR?
Wait what is a PVLIR?
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Old 10-09-2010, 10:17 AM
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Originally Posted by justinity View Post
So from stock they should be sucking in air?
The answer is yes, but it's also a case of acutely oversimplifying things...

The whole system consists of a bunch of hoses, a vaccum bell and reed valves under those covers to regulate how and when the air is sucked into the exhaust gasses... If you don't know how that operates, the information that they "suck air" is completely useless for diagnosing anything...

When you do remove the PAIR system, like has been done on your bike, they should be blocked, no air going anywhere... The "cheap" solution is to rip out the hoses, plug the hole in the airbox bottom up, flip the reed valves under the covers over and block them like with the black cap (referencing your other thread)... The good solution is to replace the covers with a blank aluminium plate, sealing the hole completely...
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Old 10-09-2010, 10:25 AM
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Originally Posted by justinity View Post
Wait what is a PVLIR?
You know, a good way of making people think you are smarter than the average bear is to use search... It gives excellent answers to questions like that...

Or you could like me, open your mouth and reveal without a doubt, to the whole world that you haven't got the sense to be quiet...
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Old 10-09-2010, 11:20 AM
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I Don't have time to search I want to DW.
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Old 10-09-2010, 11:21 AM
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I have to take some pictures I will be back
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