Ancillotti tuning
From "Motociclismo" 1968
click on page to enlarge
 
An Interesting tuning for Li and Tv Lambrettas
For the several Lambretta owners who want to improve performance on their bikes, for those not affected by speed desease who wants to obtain better acceleration and brightness on hills roads, here are some interesting tuning advices that are a good arrangement between performance and realiability, easy and economic to do, already tested on many bikes with good results.  
These for the courtesy on the owners of Ancillotti machine shop in Florence who are specialized in development of bikes with sporting characteristics and has grown their popularity owing to speed results in short distance trials on a Lambretta; Motociclismo has talk about in the last issue.  
Ancillotti's shop has gathered his best customers in its own "racing team" and is really well equipped, also with a test bench for engines, not last they works with attention to details and prudence. This enable us to give credit to their realisations and to trust in the experience of their technicians.  
The tuning we are talking about is feasible with the same methods on all Lambretta Li 125cc 150 cc and 175 Tv models of both first and second and third series.  
To turn this advices into good results is obvious to say that the engine must be in excellent mechanical order, with particular refer to crankshaft, con rod and bearings and oil seals that have to avoid oil drawing from both sides.  
The changes to be done are the following:  
1) Exhaust port on the inner side of the barrell (pic. 1) - Enlarge it by 1,5 mm making vertical sides straight and parallel. Rise by 2mm the horizonthal side , where the port begins, leaving it straight and lined up with the piston allowing gasses to flow at the same time on all port length. The edges on top and bottom of the port must be better rounded than in the central part to avoid piston rings to block on them and break down. The exhaust port on the outside barrell (pic. 2) must be risen until 24mm and enlarged until 43mm leaving it int its original shape. The short conduit in the barell thick, have to be appropriately enlarged and reshaped to the inner and outside. 
2) The inlet port on the inner barrel (pic. 3) - Make straight and lined up with the border of the piston both horizonthal sides of the port. Enlarge and polish the conduit inside the barrell matching also with the outer of the port. 
3) Transfers - Polish and enlarge their mouth (pic. 4) matching with the crankase. Be sure to eliminate every step on the walls, to allow gas flowing. 
4) Head (pic. 5) - The cylinder head surface have to be skimmed by 1mm (putting it back together use an original gasket, preferably new). In the squish combustion chamber make a little niche. It has not to exceed the thread of the plug, that have just to surface on the inner of the head, but absolutely not lean out. 
5) Piston - Eliminate the the two horisontal bars in the piston and check the edges; round them if needed. Remove 1,5mm on the skirt of piston (pic. 7) on all inlet port lenght. The border must be not rounded and have to follow all bottom part of the port to enable timing  at the same time.