I'm having my bike Dyno tuned tomorrow at the Tifton, Georgia, HD dealer. The Dyno tech came to the dealer from Star Racing and will certainly have a recommendation as to the correct air/fuel ratio, but I want to show up armed with what you think.

I have a '07 Ultra with a 103 CI upgrade, ported heads, and 10:1 compression ratio. What should the target A/F ratio be? 13.2:1 or less?

 

for low load cruise mid 14's for wot ~13.2 is normal some like a little richer.

 

so what the previous poster is getting at is that the afr needs to vary depending on what the motor is doing.

overly richer does not create power, and can cause problems over time.

so the afr will need to vary with throttle position and the load on the motor.

mike

 

Good stuff, but not what I expected. Thanks. The Dynojet tech that I talked with a month ago indicated that 13.2 afr was well on the lean side. I feel better about the setting, based on your feedback.

With 80% chance of rain over the next two days and 100+ interstate miles to ride, I'm re-scheduling the tune, hopefully to Friday.

 

Be prepared...your bike might like it but your gas mileage will suffer.

 

True Dat!

I have tuned my bike with both rich and stock type maps, through the wonderment of unregulated digital media and the opinion of every performance enthusiast with a laptop, the stock tune is now arbitrarily recognized by most as "lean", when in fact it is not lean, its damn near perfect. I cannot feel 1-3HP/TQ difference in total power, but the "lean" tune is far more responsive and mileage is a a lot better. My map transitions from 14.6 cruise to 13.2 WOT, and the bike runs fantastic. If I was drag racing, I would probably tune it differently.