Exhaust A/F question...no flaming please!

[Over_Easy]

I'm currently running Yosh RS-3 bolt-ons and a PCIII USB w/ the associated Yosh bolt-on map from DynoJet.

To experiment, I removed the mid pipes and cans and added the short 9" exhaust pipe to hear what it sounded like in person, as many have, and I really like the clean "canless" look and can feel the weight loss in the sharp twisties. It does sound mean and aggressive but admittedly starting out in first gear it's unresponsive/sluggish (almost feels flooded) then becomes more responsive as the RPMs get into a higher range.

I don't plan on running this set-up full time just maybe on rare occassion when running short solo routes...only takes 5 minutes to remove the mids and cans (4 total bolts).

My quesion is: WITHOUT GETTING A CUSTOM MAP MADE ON A DYNO for $300, WHAT COULD I DO USING THE PCIII TO ADJUST FOR THE SLUGGISHNESS DOWN LOW WHEN I DECIDE TO RUN THE SHORT HEADER EXHAUST SET-UP? TURN PC OFF, ADJUST TO MAKE IT MORE LEAN, MORE RICH, ETC.?

Thanks for the input.

 

[TXBusa05LE]

You've lost back pressure...

 

[Over_Easy]

You've lost back pressure...

Uh oh...the ol' BP debate.

To my knowledge the conclusion wasn't loss of BP just the A/F ratio adjustment. therefore, what I'm asking is does the system run rich or lean when removing the mids/cans (my belief is lean) but it seems to run rich down low, hence the bogged down result of the throttle, but it is running the RS-3 map which is richer than stock.

 

[kjcili]

personally, i didn't think exhaust could effect A/F ratio as A/F is determined by the actual intake of fuel and air metering. we use a 5 gas bench analyzer when dynoing race cars and it doesn't matter if the exhaust is 1' or 8', a/f doesn't change until the charge changes

 

[BA BUSA]

Just load a different map

 

[Got-Busa?]

According to some people on here you don't need a PC or another map, just run it off the OEM sensor.... j/k :hehe:


Just wanted to clarify that I am reading this right since the bike isn't running like you want and the bike needs a proper tune over the OEM claimed *closed loop system* and after the PC install... Sorry, had to... ...a little fun after reading some of these closed loop claims on here...





Back to business, if you don't want to spend the money your best bet is to just keep loading and trying different canned maps until you get one you like. However, you will never know if it's truly tuned to 100% until you get it on a dyno or some other tuning device.

Also if you are running a full system map, the full system tune may require more fuel in certain areas of the RPM range. The bolt-on canisters (or shorty header mod) doesn't require as much fuel as the full system which is more than likely what's giving you the rich bogged down feeling (because it is)....

 

[Over_Easy]

Back to business, if you don't want to spend the money your best bet is to just keep loading and trying different canned maps until you get one you like. However, you will never know if it's truly tuned to 100% until you get it on a dyno or some other tuning device.

Also if you are running a full system map, the full system tune may require more fuel in certain areas of the RPM range. The bolt-on canisters (or shorty header mod) doesn't require as much fuel as the full system which is more than likely what's giving you the rich bogged down feeling (because it is)....

I thought running the headers only mod exhaust would make it more lean, hence the more rich bolt-on map would help not hurt...no?

 

[Mr Bogus]

personally, i didn't think exhaust could effect A/F ratio as A/F is determined by the actual intake of fuel and air metering. we use a 5 gas bench analyzer when dynoing race cars and it doesn't matter if the exhaust is 1' or 8', a/f doesn't change until the charge changes

but it will affect the torque curve.. (moves it up) and so you can lean the motor a bit on the bottom side (requires a bit more fuel on the other end as well)

I doubt he can tune the soft spot out however... the bike needs a bit of bp to lower the torque curve back where it is needed.. (nothing for free in tuning as you know)

Might be able to compensate for it a bit with longer intake stacks? advance the cams a degree or 2