It's rather an odd system - a well tuned engine delivers more power for less emissions anyway. Surely that's better than a badly tuned system just crippled to meet EPA rules?
Really no crippling is needed to meet the EPA emissions requirements.
The current EPA test cycle for motorcycles does not need any more than ~10 - 15% throttle to complete.
The maximum speed needed is 56.7 MPH, a 1200 Sportster would be at ~ 2600 rpms in 5th gear and around 10% throttle.
Even the newer testing for 2020 only requires a top speed of 80.3 MPH, a 1200 Sportster in 5th gear would be at ~3700 rpms there and less than 20% throttle.
Once you get to 25% or more throttle, the 2007-2013 Sportsters will be running an AFR of 12.5 to 1 from ~2000 rpms and higher. (higher rpms need more throttle opening to reach a MAP that is above 90 but all rpms at about 50% throttle it will be running at 12.5 to 1)
Really no crippling is needed to meet the EPA emissions requirements.
The current EPA test cycle for motorcycles does not need any more than ~10 - 15% throttle to complete.
The maximum speed needed is 56.7 MPH, a 1200 Sportster would be at ~ 2600 rpms in 5th gear and around 10% throttle.
Even the newer testing for 2020 only requires a top speed of 80.3 MPH, a 1200 Sportster in 5th gear would be at ~3700 rpms there and less than 20% throttle.
Once you get to 25% or more throttle, the 2007-2013 Sportsters will be running an AFR of 12.5 to 1 from ~2000 rpms and higher. (higher rpms need more throttle opening to reach a MAP that is above 90 but all rpms at about 50% throttle it will be running at 12.5 to 1)
So why do people complain about HD setting their bike very lean? Seems a bit odd unless they were forced to do it.
At any rate, it still applies - a well tuned engine runs betetr than an averagely tuned one - more efficient for the same fuel input, better burning, better use of available oxygen, etc.
The only thing that forces the AFR of 14.6 to 1 (lambda 1.0) is chemistry and physics.
The EPA does not set AFR requirement they only measure the total emission of HC, CO and NOx.
It does not produce the most power or the best fuel economy.
14.6 to 1 is also where the lowest total EPA tested emissions are found without a cat converter.
When the AFR is richer there are more HC and CO emissions.
When the AFR is leaner there are more NOx emissions.
The companies would prefer to run the engines at about 15.4 to 1 to gain fuel economy since they have mileage requirements for cars/trucks.
A cat actually needs the AFR vary constantly from slightly richer than 14.6 to slightly leaner than 14.6 to remove the most emissions.
The only thing that forces the AFR of 14.6 to 1 (lambda 1.0) is chemistry and physics.
The EPA does not set AFR requirement they only measure the total emission of HC, CO and NOx.
It does not produce the most power or the best fuel economy.
14.6 to 1 is also where the lowest total EPA tested emissions are found without a cat converter.
When the AFR is richer there are more HC and CO emissions.
When the AFR is leaner there are more NOx emissions.
The companies would prefer to run the engines at about 15.4 to 1 to gain fuel economy since they have mileage requirements for cars/trucks.
A cat actually needs the AFR vary constantly from slightly richer than 14.6 to slightly leaner than 14.6 to remove the most emissions.
I've owned and used a PV since right after they became available. I've used the Autotune Pro, and the Target Tune with it. And they are nice pieces of equipment but....
I don't care how many autotune sessions you run, or how much you tweek your tune with it, you will not get what a good, competent dyno tuner can do. I thought mine was auto tuned in perfectly and the bike really ran well. Put it on the drum and easily found 10% more and much smoother operation. But, the gauges are cool.
07-20-2018, 11:31 AM
