Care to expound a little more on this ar/fuel ratio? I am trying to review a map I have to see where it may need work. Once its warm enough, I will be getting a custom map completed (Quoted $150)
The stoichiometric or chemically perfect air/fuel ratio for complete burning of gasoline is 14.7:1.
However that is only in a laboratory environment.
It's way, way too lean for an internal combustion engine.
The ideal air/fuel ratio for best power is 13.2:1.
You should strive to have that ratio across the board on your mapping.
As the air/fuel ratio starts to climb, you'll start to lose more and more power and if the ratio gets lean enough, the engine will even start to misfire or die.
If kept at a very lean state for some time, it may even start to melt the piston crown and/or spark plug.
This was a somewhat frequent occurrence in the 2-stroke racing days.
Sometimes it was caught in time, sometimes not, with a hole melted through the piston center.
If you pull your plugs and see a white insulator with gray specks, those specks are melted aluminum form the piston from overheating due to very lean condition.
You may also see melted electrode and porcelain on the plug insulator also.
This is very rare these days with fuel injection, especially systems that use a lambda sensor to measure oxygen content.
But since one can alter the air/fuel ratio with a power commander or similar systems, you can enter a too lean state if you mis-adjust the mapping.
Usually the ideal plug color is a tan or light gray color (usually tan).
Tan is a perfect ratio with light gray a tad on the richer side.
Any lighter or darker color shows which side the air/fuel ratio is at.
Here's one of my plugs from a previous mapping showing the tan color at the tip.
Here's a plug I pulled from my last valve check and plug replacement.
It's a bit of gray indicating it's running a tad on the rich side.
This is with the correct plug heat range. I'll take care of this on the next re-map session.
Also, if you run a cooler plug heat range and not get it up to proper temperature, then it may incorrectly show a darker color.