[ace.cafe]

That PAV stuff is just emission control anyway.  No reason to leave it on if you are not going to be tested for emissions.

[gashousegorilla]

Thanks for all the info. In one pictures you can see the small pipe from the manifold which runs to a vacuum type pump seen removed in one of the pictures. This pump provides fresh air to the cylinder head when the exhaust valve is closed. In my case I blanked off the cylinder head with a bold.

   Thanks for the pics Roland....  If I understand that system correctly. It would make it impossible to tune with EFI.  Your Wideband O2 sensor would have skewed readings from the air going into the exhaust port, so no good idea about what's actually going on inside the combustion chamber. And if it was tuned on a Dyno...The tailpipe sniffer wouldn't work either !  Good move getting rid of that device !!   
I really don't understand how it really even reduces emissions..... I seems like it just dilutes the exhaust at the port, instead of the tailpipe end. Without addressing what the air fuel is in the chamber ? Weird.... almost like a devise to just fool an emission tester?  And not to mention what it may be doing to performance by adding cool air to the exhaust.... But, i guess it's sorta like a smog pump on a car....

[Roeland]

Spot on - the same as a smog pump; just to foul the emission tester.

[gashousegorilla]

Spot on - the same as a smog pump; just to foul the emission tester.

  Tricky.... tricky....    Gawd, you probably picked up a couple HP with that thing removed alone !

[ace.cafe]

Theoretically, it can supply fresh air into the exhaust pipe so that any unburned hydrocarbons might be burned up in the hot pipe prior to the exit.
Also might fool the sniffer too.

[Ducati Scotty]

+1.  It's still hot enough to burn if you just add air.

Scott

[gashousegorilla]

  Makes sense..... IDM bike, with it's perhaps lower fuel grades ?  Twin spark... and the this pulse deal to help burn off any unburned fuel after ignition.

[Ducati Scotty]

And no O2 sensor.  So if it's running a bit rich this helps clean that up.

The US carbureted cars had smog pumps on them for the same reason.  It's not just dilution of the exhaust, it completes the burn of fuel.  Once you go to closed loop EFI, there's no need for it.  Closed loop EFI alone can be very clean, more so with a cat in the exhaust.

Scott

[gashousegorilla]

And no O2 sensor.  So if it's running a bit rich this helps clean that up.

The US carbureted cars had smog pumps on them for the same reason.  It's not just dilution of the exhaust, it completes the burn of fuel.  Once you go to closed loop EFI, there's no need for it.  Closed loop EFI alone can be very clean, more so with a cat in the exhaust.

Scott

    Welp..... it makes you wonder about the fuel in India. Is it THAT bad as far as it's content for combustion ?   Or is it for it content as far as emissions ?..... Or Both ? It would seem that RE is  spending more on emission controls on there IDM bikes, then they do on their export bikes.  I guess with 70 % of their vehicles being two wheeled.....


   The IDM bikes get..... A MAPed EFI,  double plugged head....  Machining and extra plug with coil /wire, this elaborate PAV system with its extra parts and machining blowing AIR into the exhaust !, dished piston to improve swirl, a TP switch......   

    We get a MAPed EFI system with a narrow band o2 sensor.... gotta be cheaper then the above.   Dished piston, single plugged head, etc....      I'm thinking their bikes might actually run lean on our pump piss !?    Maybe closed loop isn't enough with their fuel ? Maybe there is inconsistent quality levels from area to area ?..........

[Ducati Scotty]

My bet would be the inconsistent quality of fuel in India.  The base bike (IDM) is made to run on that variable with cheap EFI (open loop) and meet their emissions.  Still way cleaner than a carb.  Exports (USA, Europe) require closed loop and CAT to meet their emissions.  I suspect many of the performance limitations/compromises of the  engine would not be so if the bike only ever needed to run on high quality fuel.

There's no law requring a cat on US bikes that I know of, their is for cars.  Still, many bikes have them these days.  I'm guessing RE put it on there either to actually meet emissions or because somewhere else requires it.  Likewise, I don't know if the PAV is there because it really lowers emissions or if it's just a mandated system that must be there, even if the bike would meet emissions without it.

Smog pumps were required on US cars (not any more) and cats are required now.  EFI is not required but it's just way easier to meet emissions limits with it.  Also, less maintenance than a carb.

Sidetrack: The Honda CVCC was the last car engine to get by US emissions without a cat, smog pump, or EFI.  It basically had two intake systems and two combustion chambers.  Really tricky way to get an engine to run clean.  After a few years it wasn't quite clean enough and they joined the masses with a cat.
http://en.wikipedia.org/wiki/CVCC#Construction_and_operation

Scott

[barenekd]

GHG, since you're still running stock cams and RPM, you might want to to try the stock exhaust pipe with the Goldie Muffler. Jack tried the big pipe withe the Goldie on a stock G5 and it killed the bottom end power.
My dyno run is attached. The bike had about 250 miles on it at the time with an EFI muffler and K&N filter
Bare

[gashousegorilla]

My bet would be the inconsistent quality of fuel in India.  The base bike (IDM) is made to run on that variable with cheap EFI (open loop) and meet their emissions.  Still way cleaner than a carb.  Exports (USA, Europe) require closed loop and CAT to meet their emissions.  I suspect many of the performance limitations/compromises of the  engine would not be so if the bike only ever needed to run on high quality fuel.

There's no law requring a cat on US bikes that I know of, their is for cars.  Still, many bikes have them these days.  I'm guessing RE put it on there either to actually meet emissions or because somewhere else requires it.  Likewise, I don't know if the PAV is there because it really lowers emissions or if it's just a mandated system that must be there, even if the bike would meet emissions without it.

Smog pumps were required on US cars (not any more) and cats are required now.  EFI is not required but it's just way easier to meet emissions limits with it.  Also, less maintenance than a carb.

Sidetrack: The Honda CVCC was the last car engine to get by US emissions without a cat, smog pump, or EFI.  It basically had two intake systems and two combustion chambers.  Really tricky way to get an engine to run clean.  After a few years it wasn't quite clean enough and they joined the masses with a cat.
http://en.wikipedia.org/wiki/CVCC#Construction_and_operation

Scott

  Quite right Scott, I forgot to include the cat.   And very interesting and innovative with the CVCC......

   Some fuel info....

http://transportpolicy.net/index.php?title=India:_Fuels:_Diesel_and_Gasoline

GHG, since you're still running stock cams and RPM, you might want to to try the stock exhaust pipe with the Goldie Muffler. Jack tried the big pipe withe the Goldie on a stock G5 and it killed the bottom end power.
My dyno run is attached. The bike had about 250 miles on it at the time with an EFI muffler and K&N filter
Bare

    No Bare, It's not me with the Big Hitchcock pipe, It's Roland...... But I agree with you,especially with the stock low lift lawnmower cams.  I'm still using the stock head pipe....a little shortened......with more aggressive cams.

    Also, that's pretty intersting with your Dyno pull Bare. It's pretty damn identical to Singh's.  Except That you had a K&N in there..... And the 5900 rpm's you reved it too !?   Was that the drum roller on the Dyno ?....... or can i buy that ECU off ya ? 


 

[AussieDave]

This is all fascinating.. GHG. Did you tune the pipe length by dyno or by calculation ? I understand this can optimise scavenging at certain rpms  by getting the pressure wave resonance in time  with the valve opening. Is that right?

[AussieDave]

And wouldn't letting air in via a pav disturb that wave form?

[gashousegorilla]

This is all fascinating.. GHG. Did you tune the pipe length by dyno or by calculation ? I understand this can optimise scavenging at certain rpms  by getting the pressure wave resonance in time  with the valve opening. Is that right?

  No special calculations or a Dyno with the pipe.  Just did it by feel and sound..... must have got lucky with that one.  AND some very good idea's on it from ScooterBob.      I also think the smaller diameter pipe keeps the velocity up, with the stock displacement and rev range.  But I would probably go bigger with more displacement and rev's.......

 

And wouldn't letting air in via a pav disturb that wave form?

  That's what I was thinking as well.......