Member Contributer jefferson Posted February 11, 2021 Member Contributer Share Posted February 11, 2021 I am attempting to get the rear pair lines out and am having a ton of fun. I have read it can be done, but I am beginning to doubt that. Will the shock come out if unbolted at both ends? That is the only way I see this happening, but it doesn't look like there is enough room to remove it without removing the swingarm also. All I seem to be doing is going backwards taking stuff apart and not making any headway. Think I will take a break from it and see what you guys have to say. Link to comment Share on other sites More sharing options...
Member Contributer Fritzer Posted February 11, 2021 Member Contributer Share Posted February 11, 2021 Why do people want to remove the pair valve? What advantage is there? Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted February 11, 2021 Member Contributer Share Posted February 11, 2021 I think I ended up deciding I was never going to reinstall it (this, while fighting with it for an hour) before I folded, spindled and mutilated it on the way out. As for why, I got rid of it because I was tired of banging my knuckles into the various bits of valving, hosing and tubing cluttering up the bike. However, if you don't work on your bike, it's probably best left well alone. Ciao, JZH Link to comment Share on other sites More sharing options...
mtnpat Posted February 11, 2021 Share Posted February 11, 2021 Funny, mine came right out. With the help of a pair of side cutters 😉. Link to comment Share on other sites More sharing options...
Member Contributer jefferson Posted February 12, 2021 Author Member Contributer Share Posted February 12, 2021 It goes against my grain, but I think I will do what you did and cut it into pieces. I don't see it ever being put back on for any reason. Think I will start anew tomorrow. 2 hours ago, Fritzer said: Why do people want to remove the pair valve? What advantage is there? 2 words, clutter and weight. Link to comment Share on other sites More sharing options...
Member Contributer rangemaster Posted February 12, 2021 Member Contributer Share Posted February 12, 2021 I know everyone says it has no effect, but mine ran better with all that crap off. TPO makes block off plates for it. I sent them a gasket years ago and back came a set of plates. I used stainless button allen bolts to secure them-looks factory. Keep all the brackets and bolts - handy to attach accessories and helps with that "Factory OEM" look. Link to comment Share on other sites More sharing options...
Member Contributer DannoXYZ Posted February 13, 2021 Member Contributer Share Posted February 13, 2021 Define "better" in measurable numbers. All PAIR activity happens in exhaust-headers, so it doesn't affect anything in engine. And the extent of that action is just pumping air into exhaust to help unburnt HC finsih process. Usually what happens with PAIR is removed is you end up with crackling and popping because that HC doesn't have enough O2 to combust with. Link to comment Share on other sites More sharing options...
Member Contributer Grum Posted February 13, 2021 Member Contributer Share Posted February 13, 2021 1 hour ago, DannoXYZ said: Usually what happens with PAIR is removed is you end up with crackling and popping because that HC doesn't have enough O2 to combust with. Hey Danno. Isn't it the opposite? I thought if you remove the PAIR system then you are removing the air injection into the exhaust so there is no combustion of unburnt fuel, meaning less crackling and popping? Not so good for the environment. Link to comment Share on other sites More sharing options...
mtnpat Posted February 13, 2021 Share Posted February 13, 2021 For me as well as losing the clutter, removing the PAIR system eliminates a possible source for vacuum leaks which will definitely cause issues with tuning and engine performance. Link to comment Share on other sites More sharing options...
Magneto Posted February 13, 2021 Share Posted February 13, 2021 Exhaust has cleaner note without it... Link to comment Share on other sites More sharing options...
Member Contributer slowbird Posted February 13, 2021 Member Contributer Share Posted February 13, 2021 When I de-paired my old '97 VFR750 I noticed no change in the exhaust sound whatsoever. Link to comment Share on other sites More sharing options...
Magneto Posted February 13, 2021 Share Posted February 13, 2021 Was paar even working? I guess it is subjective... On both of mine 2 cylinders and 4 cylinders bikes note was cleaner with less drone... Link to comment Share on other sites More sharing options...
Member Contributer rangemaster Posted February 16, 2021 Member Contributer Share Posted February 16, 2021 On 2/12/2021 at 5:27 PM, DannoXYZ said: Define "better" in measurable numbers. All PAIR activity happens in exhaust-headers, so it doesn't affect anything in engine. And the extent of that action is just pumping air into exhaust to help unburnt HC finsih process. Usually what happens with PAIR is removed is you end up with crackling and popping because that HC doesn't have enough O2 to combust with. Much better idle, eliminated the slight surging at any mid-throttle setting and the removal completely eliminated the crackling/popping on deacceleration. Just my experience with this one bike. Link to comment Share on other sites More sharing options...
Magneto Posted February 16, 2021 Share Posted February 16, 2021 29 minutes ago, rangemaster said: Much better idle, eliminated the slight surging at any mid-throttle setting and the removal completely eliminated the crackling/popping on deacceleration. Just my experience with this one bike. Agreed. Danno says process but it is actual combustion producing heat and noise. Another issue related to paar is oil consumption on many engines, process where motor oil get sucked into exhaust passages due to leaking gaskets. I just bought some solid dowels to block the paar passages on my Kawasaki. Something I didn’t do last time I had valve cover off... Link to comment Share on other sites More sharing options...
Member Contributer DannoXYZ Posted February 16, 2021 Member Contributer Share Posted February 16, 2021 On 2/12/2021 at 6:01 PM, Grum said: Hey Danno. Isn't it the opposite? I thought if you remove the PAIR system then you are removing the air injection into the exhaust so there is no combustion of unburnt fuel, meaning less crackling and popping? Not so good for the environment. I had to do some measurements with wideband-O2 on dyno many decades ago to figure this one out. Let's start from known givens: 1. Factory OEM configuration - PAIR activated. No bike ever leaves factory with popping and crackling. That's just unacceptable and anti-social. 2. Modified configuration - PAIR deactivated. Has popping and crackling. Not just PAIR, but some other mods may have been done that causes popping and crackling first, then PAIR-removal may help migitate that other mod. Ultimate cause of exhaust popping & crackling is too much unburnt fuel in exhaust. Additional combustion in exhaust with PAIR's air is not initially compressed, so there's no >BOOM<. It's smooth burning like gas-stove. Additionally, the catalytic stores oxygen to combust with additional rich mixture so any extra petrol is turned into CO2 after going through catalytic. It's removal of catalytic with aftermarket exhaust that causes popping and crackles. The unburnt petrol explodes when it exits muffler and suddenly encountres enough oxygen outside to complete combustion. My '08 Ninja 250 race bike does this with removal of PAIR and catalytic while my identical '09 stock street bike doesn't. Worse at end of long straight to get exhaust nice and hot, such as going into T2 @ Laguna Seca or T1 @ Thunderhill. So there are multiple factors involved. If you bike runs better with PAIR removed, you've got some tuning and maintenance issues. After all, it didn't pop & crackled from factory. Oil getting sucked in is from worn-rings that causes pressurised crank-case that blows oil into air-box first. Then from there, it's sucked into exhaust. But PAIR is not cause of oil-burning to begin with. I figured this out with dyno-tuning many race-cars at my shop decades ago. This was caused by richness in exhaust after throttle is let-off. MAF-sensor way out by intake is still measuring air-flow, so it continues to inject fuel until air-flow stops (1/4-1/2 engine revolution). Solution to this was to use TPS idle-switch to trigger deceleration fuel cut-off. I adopted same on my race-bike by turning in pilot-screws about 1/2-turn. That reduced closed-throttle richness and crackling & popping stopped. No more meatball flags at Laguna Seca! Crackling and popping is even worse when you've got turbo with BOV. MAF is still measuring tonne of air-flow when throttle is let-off, but all that air is being dumped to atm and not going through engine. But... ECU has no idea and injects matching petrol amount anyway. Link to comment Share on other sites More sharing options...
Member Contributer Grum Posted February 16, 2021 Member Contributer Share Posted February 16, 2021 Hi Danno. Most aftermarket exhaust are just slipons and do not remove the catalytic converter. My 8gen (Pair system installed)with the oem exhaust would produce slight slight popping with throttling off but it was fairly quiet. Adding my slipon aftermarket exhaust just made it louder, and possibly by reducing back pressure also makes it worse, though I personally don't mind the crackle and pop sound. YMMV. Also, so many people state that removing the PAIR system virtually stops the popping. Lot of good info there Danno but should we be comparing all this fancy EFI car stuff with a third/fourth gen VFR? Link to comment Share on other sites More sharing options...
Magneto Posted February 16, 2021 Share Posted February 16, 2021 1 hour ago, DannoXYZ said: .... Ultimate cause of exhaust popping & crackling is too much unburnt fuel in exhaust. Additional combustion in exhaust with PAIR's air is not initially compressed, so there's no >BOOM<. It's smooth burning like gas-stove... So there are multiple factors involved. If you bike runs better with PAIR removed, you've got some tuning and maintenance issues. After all, it didn't pop & crackled from factory. Oil getting sucked in is from worn-rings that causes pressurised crank-case that blows oil into air-box first. Then from there, it's sucked into exhaust. But PAIR is not cause of oil-burning to begin with. .... I am talking about oil consumption caused by leaking gasket, usually oring, at paar port in the head. Having exhaust connection passing through valve cover and head junction- what could go wrong. Now on this smooth burning gas stove, nah... it is more like flying buzz b..b V1, due to cylinder pressure impulses 😜 Link to comment Share on other sites More sharing options...
coupedupsubie Posted February 17, 2021 Share Posted February 17, 2021 The PAIR system(secondary air injection system in the manual) was developed as a basic emissions system. If you have ever had someone say your carburated vfr bike smells rich going down the road chances are the pair system is no longer working. I deleted mine a few years ago. Last winter I overhauled my carbs. I replaced a dynojet kit with a FactoryPro kit. I don't recall getting popping on decel. If things line up just right I actually get a small fireball out the muffler when letting off the throttle. Link to comment Share on other sites More sharing options...
Member Contributer RC1237V Posted February 17, 2021 Member Contributer Share Posted February 17, 2021 4 hours ago, DannoXYZ said: 1. Factory OEM configuration - PAIR activated. No bike ever leaves factory with popping and crackling. That's just unacceptable and anti-social. You must be speaking of Honda VFR's, as I have ridden several fairly new Aprilia RSV4's, and they pop from the factory. In fact, I have no idea how those pipes pass the EPA test 😂 Link to comment Share on other sites More sharing options...
Member Contributer RC1237V Posted February 17, 2021 Member Contributer Share Posted February 17, 2021 1 hour ago, coupedupsubie said: If things line up just right I actually get a small fireball out the muffler when letting off the throttle. Two summers ago, I saw my son riding my 1990 VFR with his friends at night, and they were making fire shoot out of the exhausts. I caught up to him and he had a scared look on his face. I asked him what he was doing, and he said he was hitting the kill switch for a second, then back on, and BANG!...huge flame out the back. I told him to stop unless he wants to buy me a new exhaust... He said he learned it on Youtube... Link to comment Share on other sites More sharing options...
Magneto Posted February 17, 2021 Share Posted February 17, 2021 1 hour ago, coupedupsubie said: The PAIR system(secondary air injection system in the manual) was developed as a basic emissions system. ... That is a fact but also shame.... if the thing was sucking from crankcase horsepower gains would be substantial. Link to comment Share on other sites More sharing options...
coupedupsubie Posted February 17, 2021 Share Posted February 17, 2021 10 hours ago, Magneto said: That is a fact but also shame.... if the thing was sucking from crankcase horsepower gains would be substantial. Crankcase pressure is vented into the airbox, any fumes are getting burnt already. If you are pointing towards fuel dilution in the oil making crankcase gases more volatile then it's a moot point. The biggest causes of fuel dilution is running overly rich or poor combustion with worn piston rings. Delete the PAIR system, adjust the carbs, get it running slightly leaner but still safe. Link to comment Share on other sites More sharing options...
coupedupsubie Posted February 17, 2021 Share Posted February 17, 2021 11 hours ago, RC1237V said: Two summers ago, I saw my son riding my 1990 VFR with his friends at night, and they were making fire shoot out of the exhausts. I caught up to him and he had a scared look on his face. I asked him what he was doing, and he said he was hitting the kill switch for a second, then back on, and BANG!...huge flame out the back. I told him to stop unless he wants to buy me a new exhaust... He said he learned it on Youtube... I've only had it happen 3 times. It surprised me when it happened. From what I have gathered it is due to the engine pulling fuel without burning it completely. I need to find someone willing to put my bike on a dyno. Link to comment Share on other sites More sharing options...
Magneto Posted February 17, 2021 Share Posted February 17, 2021 3 hours ago, coupedupsubie said: Crankcase pressure is vented into the airbox, any fumes are getting burnt already. If you are pointing towards fuel dilution in the oil making crankcase gases more volatile then it's a moot point... No, I am talking about creating negative pressure in a crankcase in order to reduce pumping losses during piston downward travel. Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted February 17, 2021 Member Contributer Share Posted February 17, 2021 20 hours ago, RC1237V said: Two summers ago, I saw my son riding my 1990 VFR with his friends at night, and they were making fire shoot out of the exhausts. I caught up to him and he had a scared look on his face. I asked him what he was doing, and he said he was hitting the kill switch for a second, then back on, and BANG!...huge flame out the back. I told him to stop unless he wants to buy me a new exhaust... He said he learned it on Youtube... I thought everyone who rides in tunnels knew that? 😉 Ciao, JZH Link to comment Share on other sites More sharing options...
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