Vespa Conversion mixture adjusting screw bgm PRO for SI carburettors Dell’Orto & Spaco
Mixture adjusting screw bgm PRO for conversion of Dell’Orto SI carburettors with long hexagon mixture adjusting screw to short slotted screw. This bgm PRO conversion air mixture adjusting screw is used to use carburettors with long hexagon mixture adjusting screw also in older engines (with stud bolts for carburettor mounting). It replaces the too long adjustment screw on new Spaco and Dell’Orto SI carburettors and allows a trouble-free installation of the carburettor. Due to the shorter screw, the carburettor bowl can be left original! Fits all carburettors with long hexagonal mixture adjustment screw. (Used ex works in PX models from approx. 1989 and all new Dell’Orto/Spaco SI carburettors)
Carburettor air mixture adjustment screw too long?
A carburettor is also a wearing part and sometimes it is simply not enough to clean a carburettor, you need a new one. Especially if you want a bit more power and adjust your engine setup, you usually need a new, bigger carburettor. Below you will find instructions on how to install the SI carburettor. 
SI Carburettor for Vespa
Today all new carburettors come from SPACO, even if it says Dell’Orto on it. New SI carburettors, whether from Dell’Orto or Spaco, are always supplied with a long (brass-coloured) hexagonal mixture adjustment cap. The exception is our bgm PRO Faster Flow carburettors – but more on that below.
Problem with too long air mixture adjusting screw
For carburettor sumps for engines without separate lubrication, this presents us with a bit of a problem, because:
- the carburettors no longer fit properly in the sump
- if you have somehow managed to get it in, there is no longer a rubber seal on it
- and it is difficult to get at it
With the mixture adjustment screw too long, it looks like this:
And this is how it should actually look:
bgm PRO conversion air mixture adjustment screw
Now you could get the idea and simply screw the old, short air mixture screw into the nine carburettor. Unfortunately this does not work, because the threads of the new Lusso carburettors are different. Please do not try to force it, the different thread pitch will destroy the fine thread in the new carburettor and make tuning impossible. Our conversion screw provides a remedy: With our short mixture adjustment screw for slotted screwdrivers you can solve the problem cheaply, easily and quickly. 
bgm Faster Flow carburettor
Alternatively, you can use a bgm Faster Flow carb urettor directly if you are already ordering a new one anyway, here we have already provided the update. The bgm carburettors come, for the models without separate lubrication, directly with the short conversion screw. 
