another stupid carb tuning question... air fuel screw

[cirame1]

well i have a mikuni 28mm flat side carb. ive always wondered about the air fuel screw and i need to have mine adjusted. my carb has 2 screws on it. 1 is on the left side of the bike near the choke and is a bigger size turn screw. im assuming thats it, but wen i adjust it it doesnt seem to do anything at all. also there is a little gold flat head screw near the opening to the carb on the opposite side. is this an idel screw or wat? i want to preoperly tune the bike i have stock pilot jet and a pretty big main jet but still seems out of wack.

 

[robert0762]

Usually the screw to the back is the air screw and the front(meaning motorside) is the idle screw

 

[blaster biotch]

if you turn air/fuel screw more than 2 1/2 turns out and it does nothing ur pilot is too large

 

[blasterman87]

U mean if its still idling up after 21/2 turns the pilot is to big?

 

[cirame1]

well i have 2 screws and 1 is on the kicker side small and gold near opening to carb and other is on other isde in middle bigger screw which im thinking is the air screw. ive screwd that out and in and seems to not do much at all. i think my pilot is to big but i removed it and i belive its my pilot its real thin and gold cant really read a number off of it. i removed my stock carb one and its way smaller and cant seem to get a number off that either. but on the air fuel screw i have it 1 and a 1/2 turns. say im running rich whihc directipon is to lean it up outward?? and also anyone know the stock pilot number b/c i want to try to find out wats a good number for me to run im assuming near stock? thanks

 

[quam]

first things first, the thumbscrew is your idle and the flathead screw is your pilot adjustment. the idle screw should speed the engine up when you turn it in. if you turn it out too far, it should cut the engine off.
the pilot screw is either an air screw or a slow/pilot jet adjuster. mikunis tend to use air screws. if the pilot screw is on the airbox side of the bowl, it's an airscrew. if it's on the engine side of the bowl, it controls the fuel metering.
so, i'll assume it's an air screw (on the airbox side) since it's a mikuni. if you turn it out more than 4 full turns from lightly seated and the plug still reads rich, then you should def jet the pilot jet down. the pilot jet is inside the carb, you'll have to pull the bowl off. and it does have a number on it somewhere, just look closely. you might need a magnifying glass.
remember to always check the plug to give you a reading on the jetting condition.
why is it that you think your carb needs tuning? gimme the symptoms and we'll see if we can diag your issue more precisely....

 

[cirame1]

well its running rich but only on low throttle. i have a 280main in and im pretty sure i should be going higher. i moved the needle clip up 1 like a month ago and it seemed to fix it but mayb leaned it tomuch on the low end. i recently put a new top end with a milled head and ported cylinder and i moved the clip back to the normal spot. im running no lid and an fmf full exhaust. so i pulled the piot jet and couldnt read the number on it and i pulled the pilot out of my stock carb and couldnt read it either. but the stock one was smaller then the one in my 28mm by a good amount. so im assuming maybe i need to go down slightly on my pilot or mess with the air fuel screw. the little screw ison the intake side of the carb.

 

[cirame1]

pilot jet question winner gets a cookie.... my stock carb is a mikuni??? my current carb is a mikuni 28mm flat side?? are the pilot jest interchangeable??? i want to go down on my pilot and i am yet to read the number soff both but visibly the 28mm one (current) is a bit larger than the one in my stock carb. can i swap them?? or no thanks