I noticed something a little bizarre. For fun I "disabled" the PAIR system by clamping the air feed under the carbs with a large clamp to see if it would help the popping and low and behold the popping mostly was killed. Not %100 but like %90 percent gone. But what I didn't expect was that it seemed to run a little smoother at idle for some reason. For fun I took a look at what the PAIR valve actually does and from what I gathered its such as piece of shit!!! It's not doing anything really. There is the same amount of exhaust gasses but on the exhaust stroke there is a reed valve which pumps in some fresh air into the side of the cylinder to mix with the exhaust gasses to dilute and "fool" the EPA sensors into thinking there isn't as much hydrocarbons. There is still the same amount of shit coming out of the pipe it's just "diluted" now.
Do the EPA not have a brain? Or they don't give a shit as long as they put their schtick sensor at the back of the tailpipe tells them x amount of crap is coming out? If Suzuki really wanted to go jihad with this clean air crap, why not just drill exhaust holes along the inside of the pipe? I bet you could get the crap comming out of the tail pipe equivalent to a 50cc motorcycle if they made the exhaust pipe out of a wire screen!
Well now back to why I think its actually a little smoother when at lower rpm's and idle speed. With a stupid ass hole at the side of the cylinder pumping in extra air at the exhaust stroke, at lower piston speeds it must be disrupting the flow of the engine slightly. At lower piston speeds any little disruption in the normal function of the engine will aggravate any slight differences in carburation between the cylinders. While plugging up the hole won't give you more power, I can see it smoothing the engine out a bit. Having an extra air leak out of the airbox isn't doing you any favors either. It must be slightly disrupting the normal exhaust scavenging which would be aggravated at slower piston speeds. Not only does it have to push out the normal exhaust gasses but a reed valve feed amount of normal air as well.
What a shitty ass system! I'd rather they leave the damn cylinders alone and have the "EPA exhaust dilution system" pump air into the exhaust collector or something. Anything but drilling holes in the engine block! Needless to say I've disabled it for now by removing the PAIR air feed hose and folding it over and tied it off with a tie down and plugged the hole in the airbox. It's not perfect as there still is the plumbing there but it's better than nothing. In the spring I'm going to fabricate some block off plates out of paper mache if I have to.
I wonder if this might be part of the problem when the bike has a lean "sneeze" backfire when cold. When cold, the bike will not burn all of the fuel efficiently or completely so you may have say like %1 or %2 percent of the fuel charge not burned when cold. However on the power stroke the fuel charge gasses that were burned are superheated, mixed with the unburnt fuel all it would take is a bit of oxygen to burn off the rest of the unburnt fuel which I believe is part of the PAIR function. The problem is if there is a %1 or %2 fuel charge still in there mixed with the superheated gasses it's actually creating a mini-power stroke! The engine is actually working against itself which is probably why the rpm's drop so much when the "sneeze" happens. Now fortunately the exhaust valves are open so there is no rod crunching compression but since the rpms drop so much I imagine the overall pressure is still more than what the exhaust valves can scavenge properly at low rpm's. If your valves are out of wack I could imagine this effect must be aggrivated as maybe the valve timing might be slightly off which may create a higher pressure wave with less exhaust holes for the burning gasses to escape. And I'm sure that pressure wave is not doing you any favors as far as the valves and rods are concerned.
When the engine is hot this is really not a problem because the unburnt fuel will be probably in the 1000ths of %1 if that. However the burnt fuel will still be slightly combustible similar to the gassification principle, Hence the need for a PAIR system to dilute and possibly ignite any minute traces of unburnt fuel. I haven't tested to see if there is less "sneezing" without the PAIR system as I plugged up the PAIR crap when the bike was warm but next time I do my monthly winter start and warmup run I'll try and notice to see if the sneezing is reduced slightly without the PAIR crap working on there. I imagine there might be still some but it may be drastically reduced or the "sneezes" might be of a lower power. Since this is my first bike with this PAIR crap on it, I've never had this sort of lean "sneeze" on my other bikes and I've owned at least 10 other bikes than this one of all makes and sizes from completely stock jetting to stage 3 pods.
Did anyone else here notice the engine at low rpms becoming slightly smoother and a little less "sneezing" with this PAIR crap off? I'm going to test this next winter engine run to make sure it's not a placebo effect however I think the theory is sound otherwise the bikes from day 1 of the combustion engine would have "air holes"(??) drilled in the engine blocks. Another factor which gives me pause is in the clymer manual under PAIR servicing it tells you to check for carbon build up in the PAIR reed valve which scares me. Where is it getting this carbon build up? I hope to god it from the exhaust stroke and not the power stroke!!!
Topic: PAIR disabled = smoother idle? (Read 6595 times)