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Kawi invented and patented a pollution control system that appeared on the 1979 and later models that was ingenious and helped them to meet the new more stringent emission regs without leaning out the AFR if this system was not used.
There were "sub ports" cast into the heads that started at the main exhaust ports and ran up thru the head, mating with ports in the valve covers that traveled up to a chamber which held reed valves. A cap bolted to the head over that chamber had a spigot for a hose that connects to a "switching" valve which had a hose feeding into the airbox.Exhaust velocity traveling past the sub ports created a vacuum that pulled air for the airbox, adding a dose of oxygen to the exhaust gas helping reduce hydrocarbon emissions. The reed valves in the valve cover insured that flow only went into the ex ports and if there was some sorta bang in the exhaust nothing would enter back into the airbox. The switching valve was used to shut off the airflow into the ex ports on decell so popping out the exhaust would not occur. Such a simple and elegant method rather than the air pumps used on cars.
I guess when the patent ran out or Kawi has decided to lease it out, all Jap skoots now have this system. Indian does not have this technology and that may be one more aspect needed to help meet emission regs.

RACNRAY
 

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'17 Springfield, '20 Chieftain
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Kawi invented and patented a pollution control system that appeared on the 1979 and later models that was ingenious and helped them to meet the new more stringent emission regs without leaning out the AFR if this system was not used.
There were "sub ports" cast into the heads that started at the main exhaust ports and ran up thru the head, mating with ports in the valve covers that traveled up to a chamber which held reed valves. A cap bolted to the head over that chamber had a spigot for a hose that connects to a "switching" valve which had a hose feeding into the airbox.Exhaust velocity traveling past the sub ports created a vacuum that pulled air for the airbox, adding a dose of oxygen to the exhaust gas helping reduce hydrocarbon emissions. The reed valves in the valve cover insured that flow only went into the ex ports and if there was some sorta bang in the exhaust nothing would enter back into the airbox. The switching valve was used to shut off the airflow into the ex ports on decell so popping out the exhaust would not occur. Such a simple and elegant method rather than the air pumps used on cars.
I guess when the patent ran out or Kawi has decided to lease it out, all Jap skoots now have this system. Indian does not have this technology and that may be one more aspect needed to help meet emission regs.

RACNRAY

Hey Ray, that's an interesting bit of information, thanks for sharing. When you said "adding a dose of oxygen to the exhaust gas helping reduce hydrocarbon emissions", does the O2 just dilute the exhaust, or does it aid the Catalytic in the destruction of emmissions?
 

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Hey Ray, that's an interesting bit of information, thanks for sharing. When you said "adding a dose of oxygen to the exhaust gas helping reduce hydrocarbon emissions", does the O2 just dilute the exhaust, or does it aid the Catalytic in the destruction of emmissions?
Since the air entering the exhaust port and it's oxygen content helps to burn unburnt fuel this reduces how much the cat has to do, thus there is much less need to lean out the AFR to meet the emission requirements and preserving performance.
 

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Since the air entering the exhaust port and it's oxygen content helps to burn unburnt fuel this reduces how much the cat has to do, thus there is much less need to lean out the AFR to meet the emission requirements and preserving performance.

The Yamaha V Twins had the AFR way leaned out in closed loop, 14.7.1 So I don't think that method meets todays more stricter standards. But they also don't use the system you speak of either.
 

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Amazing power, but ugly as sin in my opinion. If they were to dress these up with some chrome and fins to at least resemble an air cooled engine they'd be much more visually pleasing.
Several months ago someone on the site posted that the PP108 looked like a two cyl compressor LOL.
 

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Hey Ray, that's an interesting bit of information, thanks for sharing. When you said "adding a dose of oxygen to the exhaust gas helping reduce hydrocarbon emissions", does the O2 just dilute the exhaust, or does it aid the Catalytic in the destruction of emmissions?
When cars and trucks needed to meet tougher and tougher emissions this was one of the tricks. Mfgs pumped air ahead of the cat converters to aid in burning off emissions. Exhaust gasses have very little oxygen present to aid in "burning" so adding it would increase the temp of the cat and aid in burning off contaminants.
 

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When cars and trucks needed to meet tougher and tougher emissions this was one of the tricks. Mfgs pumped air ahead of the cat converters to aid in burning off emissions. Exhaust gasses have very little oxygen present to aid in "burning" so adding it would increase the temp of the cat and aid in burning off contaminants.
See my post #3 above, Kawi started using what is called their Kleen air system back in 1979, 20+ years b4 catalytic converters were put into usage,which used the velocity in the exhaust ports to create a vacuum in passages leading back to the airbox. No pump needed and 99% of Jap bikes use this system to this day.

RACNRAY.
 
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