Setting carb jets

[Anonymous]

81 750 L w/ mikuni carbs. 37k miles. started running poorly one week after i bought it. erratic idle, stalling, bogging at 1/4 throttle. i tore down and cleaned all four carbs. my carbs do not have adjustable air screws. synchronized the carbs today. still bogs at 1/4 idle. #2 carb rich. spark plug very carbonized, but not wet. no black smoke. erratic idle, and engine will die sometimes. my questions: 1. do the air, main and pilot jets have specific settings, or do they just get tightened all the way down? 2. which jets control the lean/rich mixture? 3. how do i lean out the #2 carb? thanks for your help.

 

[SqDancerLynn1]

on the intake side of the carb there is a small plug that needs to be removed (drilled) to access the screws. I would also check the fuel valve vaccum line, the smaller one that goes to the front of the #2 carb check it for fuel. if the fuel valve is leaking it will suck fuel into the carb and make the #2 cyl run very rich, it could also be the floats sticking for some reason. Check to see if fuel is comming out of the overflow vents

 

[Anonymous]

HEY! Fixed it.

HEY! Fixed it.

i broke down the petcock, and sure enough the diaphram was bad. i got a $25 rebuild kit and the bike runs great. thanks for your help. :lol:

 

[Anonymous]

Halo, What does the diaphram look like, does it have holes??

 

[Anonymous]

diaphram

diaphram

yeah. it had small holes. the metal plate in front of the spring had broken. it must have punctured the diaphram.