we all want mileage, we all want power. whats the happy medium? im willing to sacrifice a little power to get more mileage. i want to tweak the a/f ratio in the 2300-3000 rpm cruising range. i have a power commander 5, the common bolt on's, and tman 555 cams.

 

Has it been tuned or are you using a generic map?
If it's been tuned you should be able to rely on the AFR being close to ideal and safe.
Then you could highlight the area you feel you would be happy with and reduce that area by 5 points and see if you notice a change in performance. If none try another 5 and repeat.
Once you start feeling the smoothness and power degrade, you simply go back to the previous settings. Then check mileage.
If the bike has not been tuned you dont know where the AFR is in the area you want to change (baseline) so tuning advice is no good.
Bob

 

i am using a generic map from dynojet's website. but i can change the cruising range area to a different a/f setpoint and let autotune achieve that setpoint

 

Since you have the auto-tune you should be able to choose 14.5:1 in the area you want and if the system is working properly, will tune itself right in.
If the base mapping and auto-tune aren't working properly those changes will not net the expected results.
Good luck to you,
Bob

 

yes, i understand that. but my question is related to the actual A/F setpoint. how lean is TOO LEAN?

 

I wouldn't go leaner than 14.6 AFR at cruise.
Bob

 

It's all about managing heat. Honda for years has run what they call lean burn engines. They have gone as far as 18:1 AFR but it's very hard to do without doing some tricks to keep it happy. You will never get there on a HD engine but you must manage the heat and as long as you keep that in check then I would not see a problem running as far as a true 15.5:1.

 

I looked at a PowerVision Stage 1 tune for a Touring model. They have a Lambda based AFR table and a Closed loop Lambda Range tune setting.

The 2017 Touring Stage 1 tune from PV has an AFR (shown as AFR for gas) range of 14.3 to 14.9.
The 2014 Sportster Stage 1 tune from PV has an AFR (shown as AFR for gas) range of 14.2 to 15.0.

I would probably try adding 0.2 to what you have now, try it, let it auto tune, if it is running great, add 0.2 more until you start to notice driveabilty issues. I probably wouldn't go past about 15.0 to 1.

 

Always wanted to hear back from someone who has run his bike @ 15.5 AFR.
Let us know,
Bob

 

How much ethanol does your fuel have?

That may make a difference in the "Stoich" number.