help air fuel mixture screw side to enrich

buddy burger · Post by **buddy burger** » Sat Oct 03, 2020 9:59 pm

on a buddy 50 (keihin carb) which of screw or unscrew will make it richer? its different from carb to another

thanks!

tenders · Post by **tenders** » Sat Oct 03, 2020 10:51 pm

Out is richer, in is leaner.

At least thatâ€™s what I carefully made a point of writing down in my notes when I last was fiddling with the carb.

babblefish · Post by **babblefish** » Sun Oct 04, 2020 8:33 am

tenders wrote:Out is richer, in is leaner.

At least thatâ€™s what I carefully made a point of writing down in my notes when I last was fiddling with the carb.

I guess the idle mixture screw for a 50cc engine is different from the 125/150cc engines. On my 150, the mixture screw adjusts air flow so turning it IN reduces the amount of air resulting in a richer mixture.

tenders · Post by **tenders** » Sun Oct 04, 2020 12:17 pm

I donâ€™t have a larger Buddy to compare to but idle mixture screws work in opposite ways in different carb designs. Some control idle air, and some, idle fuel. My notes on my Vespa S150 suggest that its carb works the same as the Buddy 50, though Iâ€™m not 100% sure of that. Both are Keihin carbs. I have an old inboard boat engine that uses a Zenith carb, and itâ€™s the opposite. In stock carb adjustments, youâ€™re usually trying to set it between two extremes of â€œtoo richâ€� and â€œtoo lean,â€� and which extreme is which doesnâ€™t really matter.