Is the carb a Mikuni ? ... The choke is on when the brass plunger is pulled upwards (out of the carb body) ... Some people get it messed up in reverse and think the choke is on when it's off ... not sayin' that's the situation here ...
All you can do is clean the carb up spotless , blow out all the jets and ensure you can see daylight thru them ... Check that everything is where it should be ... then ensure that fuel is filling the float bowl to the correct level ...
Some carb "problems" can be caused by blow back past an inlet valve that's being held off the seat due to a lack of proper rocker to stem clearance ...
Always check and re-adjust valve clearances (if necessary) to eliminate that doubt before messing with the carb ...
As a matter of fact ... my relo Davo recently had problems with a 110 engine ... The engine wouldn't start ... he had messed with the carb and carried on for weeks before asking me to take a look at the valve clearances (which he said he had adjusted) ... On removing the caps to check , I found the inlet rocker adjuster screw just about hitting the cap with no lock nut anywhere in sight ... The inlet valve was getting about 2 mm of lift and around 20 degrees of duration ... The exhaust rocker still had the lock nut there but the adjuster screw had screwed in and was holding the exhaust valve off the seat ...
Both rockers are stuffed because the engine had been running that way and the threads were all chopped out in both of 'em ...
Moral of story ... Check both ya' nuts to make sure they're tight ...
