Does exhaust back pressure affect tuning?

[HardDrive]

When one buys a full exhaust system for a motorcycle, this is typically paired with a new air/fuel map of some sort.

Why?

Is the new mapping there only to take advantage of the new open exhaust, and increase performance?

Or is the map there because it is required to keep the engine running well with the reduced back pressure? To put it another way, could I put straight pipes on a modern FI bike, leave the mapping stock, and drive it without causing long term harm?

[carambola]

i think it has to do with heat

the less heat intrusion, the better controlled the combustion.

[dlockhart]

Stock maps are necessarily emissions friendly and generally lean. Any improvement in flow is going to make it worse. Yes, you could probably ride it and be fine.

The flip side is, ride a well tuned bike, where the map and ignition and cam timing are dialed in and you won't ever want to settle for less again.



I am using a Bazzaz on my 08 zx6r race bike with a full Ti Akro pipe.
After some time on the dyno I have 117hp at the wheel on pump.
The on/off throttle mid corner transiton is nice and smooth. I can dial on the power and just get the back spinning up that little bit to fininsh the turn and start the drive.

[sc_rufctr]

Back in the day I used to retune my motor cycle whenever an exhaust pipe was changed.
Generally the less back pleasure the more lean the motor will run.

It was easy to do with carbs and probably easier with EFI but I've never had an EFI bike. (old bastard)

[svandamme]

If all else is equal , less back pressure will lean out the mixture because the engine pumps more air and if not taken care off can cause burnt valves cause of hotter combustion temps