The ideal Air Fuel Ratio (AFR) for gasoline engines varies from 14.7:1 to 13.2:1, depending on the engine design and performance targets. 14.7:1 is considered a "stoichiometric" ratio, meaning it represents the precise balance of air and fuel needed for full combustion. 3) Tune-up. The tune-up activity is the act of ensuring the burners are properly mixing the air and fuel and of reestablishing the most appropriate amount of excess air throughout the operating range of the boiler. a) Tune-up each operating position of the combustion control system (from high-fire through low-fire). Oct 11, 2013. Don't be afraid to adjust the carb with more than just your idle-air screw! The opening line says it all, right? Install a new carb or one that you just found at a local swap meet Get the idle air/fuel mix in the 14-15:1 range at idle, transition, and cruise, and you're way ahead of a carburetor that dumps 10-11:1 buckets of gas through your motor. During light load The LM-1 includes Logworks software that has the ability to display AFR (air fuel ratio) charts that can be used to update your EFI fuel maps and create very accurate tuning. Surprisingly, this very useful little performance tool has not caught on with the two-wheeled crowd to the same extent as it has with four-wheelers. Tuning Tuning the air/fuel mixture on a supercharged engine Modern technology has supplied the tools that make it possible, at an affordable cost, to properly tune the air/fuel mixture of a supercharged engine. One of the best methods for determining what the air/fuel mixture (jetting) is -- on any engine -- is the 3884 posts · Joined 2006. #2 · Aug 28, 2008. narrow band gauges are useless. widebands are very useful. in order to tune the carb for max power i use an air fuel gauge to get right in the ballpark, then move up/down a jet size at a time testing at the track to see where your motor actually makes best power. max power WOT AFR is between 12.8 Wide-open throttle tuning is the easy part. A naturally-aspirated engine safely produces maximum power when the air/fuel ratio is approximately 12.9:1; depending on boost levels, turbocharged and supercharged engines respond best to air/fuel ratios between 11.5:1 and 12:1. The fuel mixture gauge displays the air–fuel ratio of the currently installed carburator while the engine is running. The gauge must be wired in order to function. Note: The gauge is most accurate when the engine has warmed up to a stable idle temperature, which is at the halfway mark on the temperature gauge on the dashboard. Car parts. You should probably have a good part-throttle closed-loop tune to start. There are a couple of different options for using the wideband after that. You can just keep your closed-loop tune as is, and focus on PE AFR with the wideband, or you can tune open-loop and use the wideband across the chart. I have been using the second option lately. 7gP1.