HI, Does anyone know the default screw settings for a Mikuni BS 24 carb as on my 1998 Piaggio Liberty 125 pre-leader?
Thx for the reply. Can you confirm the location of the mixture screw? The only 'screw' (which looked like an adjustment screw) I could find on it was 3.5 turns out and located on the left side (throttle cable side) of the outlet. See pic below.
That's the tick-over screw, the mixture screw is probably on the other side and does not stick out but sunken in to the carb body.
by tick-over do you mean idle? The red arrow is pointing to a recess in the carb body behind the throttle cable holder where there is a screw (this isn't my pic nut downloaded from the net). I have tweaked my picture
Yes, tick-over= idle, and yes that could be the mixture screw, that is an old scooter, the pre-leader engine was lovely motor I no cos I had one for a while, smooth as butter!
Mine was lovely too for some time until last week. I will set that screw at 1.5 turns out and see what happens. It was 3.5 turns out before I stripped the carb and cleaned it out. I set it on 2.5 turns out (another forum post I found stated the default for piagios was this) and when I put it back on the engine fired up after about 4-5 blasts on the starter and was a bit rough but settled down and when I took it for a test ride it was very punchy The next morning was a different story - first blast on the starter and for 2-3 seconds it sounded like it was going to start then nothing. It took about 10 goes on the starter and pulsing the throttle not too much before it would start and that was at a very low and rough idle - had to hold the throttle open slightly as it sounded like it was going to die. After a couple of minutes it was much happier sounding. I will post back tomorrow.
Right that took longer than expected I have set the screw at 1.75 turns. First attempt at starting and it fired up surprisingly quickly - revved ok and on the test ride it seemed 'punchier' than before. However, the next morning it was back as before - starting seems pretty random and you have to pulse the throttle - sometimes makes noises like it wants to start quite soon other times nothing for a couple of blasts then it starts. Idling when COLD is very rough and very 'put put put' and the revs starts to drop slowly and it dies anywhere from 30-60 seconds if not given throttle. When WARM idling is similar but it doesn't die. I have tried adjusting the tick over but it seems to have a HUGE flat spot of about 2 turns where nothing happens then all of a sudden the revs shoot up and the wheel turns. Riding it seems normal.
