so here is the problem,my khyber's carburetor is out of tuning. on petrol though only,it gives a little black smoke. what i think is its because of car running too rich,ive tried to adjust air-fuel mixture and not much of a help out of it.
ive read on many sites sayin that
"There are no exact settings for a carb.Here is a previous answer i gave telling how to set a carb that should work just fine for you.On the body of the carb there will be a screw(usually brass).Screw it in clockwise til it lightly seats.Don't screw it in too tight as it will damage the tip.Then screw it out 1 1/2 turns.Start the bike.For the following adjustments go 1/4 turn at a time giving the bike about 15 seconds between each adjustment to react to the new setting.Start screwing the screw out(richer) 1/4 turn at a time til the engine starts to stumble from being too rich.Then counting the number of turns you make screw the screw back in 1/4 turn at a time(leaner) til the engine speeds up and dies from being too lean. Stop there.Now screw the screw back out half the number of turns you screwed it in.For example if you screwed it in 3 turns you would screw it back out 1 1/2 turns.It should be very close to being right.Adjust the idle and ride it.If need be fine tune the adjustment richer or leaner 1/4 turn at a time riding the bike between each adjustment""
copied from yahoo answers.
now problem is when i screw it in clock wise,car's rpm increases but never comes down when even ive screwed the screw all the way in which i think is wrong,it should lean out and start to stumble.. any ideas?
carb was cleaned with carb cleaner, NO RESULTS
carb settings were adjusted with 3 different mixture screws, NO RESULTS..( all have different length of tip )
mechanic told its due to some butterfly thingy gone bad in carb,so before i get the carb open,i wana get expert's opinion. car was all good a month back,and without any fiddling around,this started to happen..
PS: The float level in carb is adjusted to factory's recommended level,i-e 7 mm.. read it in manual here on pakwheels
and if some one knows any good carb mechanic in rawalpindi,do post name,location etc