Scooterotica

SIL 200 engine with a 24mm Dellorto phbl carb. Starts after a couple of kicks but I need to leave on choke for a bit. Then I need to rev it and keep up revs or it cuts out. When it warms up it stays running, but if I park up and let engine on it will slowly die out and eventually cuts out. Any ideas as to why.

Disclamer: I am mechanically inept so please tolerate any silly questions from me.

I have had the same issues with a PHBL24 and 25 carb on the same SX150/175. I have written it off to a peculiarity of these carbs. One or two kick scooter, always needed to crack the throttle a bit, and it will die off if I don't keep blipping the throttle, idles/runs great after it's warmed up.

starreem wrote:I have had the same issues with a PHBL24 and 25 carb on the same SX150/175. I have written it off to a peculiarity of these carbs. One or two kick scooter, always needed to crack the throttle a bit, and it will die off if I don't keep blipping the throttle, idles/runs great after it's warmed up.

Thanks for that. I think what I am more concerned about is the fact that even after it's warm it's likely to cut out after a few minutes, if I leave it idling.

The choke richens the mix. As soon as you take the choke off, it sounds like you are going too far the other way ie. it goes too lean, which is why it stalls. Sounds like you need to richen your mixture screw and/or pilot jet

storkfoot wrote:The choke richens the mix. As soon as you take the choke off, it sounds like you are going too far the other way ie. it goes too lean, which is why it stalls. Sounds like you need to richen your mixture screw and/or pilot jet

Air mixture screw or throttle stop screw?? And to richen do I turn it left or right??

Please remember my disclaimer in the first post.

Don't try any carb adjustments unless your engine is fully warmed up. Anti-clockwise on the mix screw will enrich the fuel/air mix. Generally speaking on any carb, if the mix screw is on the engine side of the slide, it's a fuel mix screw; on the air intake side of the slide, then it's an air mix screw.

I've found it easier on this carb to raise the idle speed (throttle stop) screw a few hundred rpms, and then adjust the mix screw. I give it only a 1/4 turn at a time, and 15-20 seconds for the adjustment to take effect. I go back to a nominal idle speed when I'm done with the mix screw.