| The following 3 examples are from a Dellorto jetting database (most of the others didn't supply all the necessary data which limited the examples available). But this shows how the Dellorto Calculator mostly agrees with reality and also shows how they can be improved. The following example shows the Dellorto jetting specific to Aprilia RS125 which is almost perfect other than being slightly rich from 5/8 to 3/4 slide.  
This Lambretta is not too bad. I would use a fatter needle jet, a smaller diameter needle to richen it up at 3/8 slide, and try to find a needle with a lesser taper angle (although Dellorto sometimes have none that are with an ideal slight taper).  
This is nearly the same but notice that some of the leanness at 3/8 slide was eliminated by using a fatter needle jet.  
This is OK except for the lean zone around 3/8 slide.   Here is the same setup with a slightly skinnier needle with a 1.6 degree taper instead of the previous 2 degrees. Using a slighter needle allows you to raise it so it kicks in quicker to eliminate that lean zone, but without causing too much richness at half throttle. 
|