hi i got a extreme fligth yak 54 i am using a zenoah g 62 modified ports excellent power plant alot of power but when i put the cowl the engine goes rich i need help ? please maybe is the big intake that dont work good or too big exit? i am using spinner

if air is forced into the carb when the cowl is off, maybe putting the cowl on blocks air to the carb, resulting in running to rich?

try to tune it with cowl on, obviously.

or you could try to baffle it so as to get air into the carb like when cowl is off.

i will try on somenzini yaks they are flat on the front may that big hole in front is the problem what you think?

You need a velocity stack to run from the carb to outside the cowl.

i am using a velocity stack , i look for 3w article that says that you have to put a brass tubing upside the hole of the carb and a gas tubing on to the firewall , lets see if it work