Mikuni

Hi folks
Currently restored a Lambretta D 150 mk2, just started it up, however the old dellorto is the original and its worn. It’s on a 6volt system Marrelli system, I have fired it up with the original carb so it runs but had trouble starting it. It has good spark, plug gap checked, points gap checked, new condenser, timing is set. It ran after about 10 kicks for a good 5 minutes but don’t want to keep the original on it.
I Have changed the carb to a new mikuni vm20 carb as I had a new one spare, it will start on choke, but take the choke off it dies, choke back on it runs but you have to keep using the throttle to keep it from dying, it sounds like fueling. Before I start messing with the fueling any ideas?
Have checked there is fuel to carb, no kink in pipe, I have good flow, new petrol tap, new tank as the old was knackered.
Currently restored a Lambretta D 150 mk2, just started it up, however the old dellorto is the original and its worn. It’s on a 6volt system Marrelli system, I have fired it up with the original carb so it runs but had trouble starting it. It has good spark, plug gap checked, points gap checked, new condenser, timing is set. It ran after about 10 kicks for a good 5 minutes but don’t want to keep the original on it.
I Have changed the carb to a new mikuni vm20 carb as I had a new one spare, it will start on choke, but take the choke off it dies, choke back on it runs but you have to keep using the throttle to keep it from dying, it sounds like fueling. Before I start messing with the fueling any ideas?
Have checked there is fuel to carb, no kink in pipe, I have good flow, new petrol tap, new tank as the old was knackered.