Carb. Jetting using an A/F gage

[XR250]

I need to adjust the jetting on a new build for a 125cc Honda Navi. Started as 110cc and added a cam, pipe and carb and bore. I just installed an A/F gage on it.
If for example, it says I am at 11:1 at WOT, and am running a 110 Main jet, should I try a 11/12.5 x 110 = 98 (say 100) main jet assuming I want 12.5:1 as my target mixture?
Also, is 12.5 a good number for WOT? What should I be shooting for a low and mid throttle?


Thanks

 

[XR250]

There might be something found in tailoring the length of that runner to the operating RPM of the engine.

Maybe but not enough motivation here for that

 

[XR250]

So after many permutations of jetting and sanding the carb needle, I am back to the stock carb needle dropped as low as it will go, a 32 pilot, 115 main.
Idle, midrange and WOT are all about perfect with 14.5:1, 13.5:1 and 12.6:1 respectively. 1/8 ish throttle is lean running 15-16 AFR. It runs OK in this range and it is about 30 mph so i am here a lot. Is it going to damage the engine at this low load due to lean overheating? I can try a new needle and just lightly sand it to get the ratio better in this range but I do not mind how it runs now.
I think I saw a dyno pull of a new Honda XR150 and it was in the 17's at part throttle.