Cylinder Identification

[Hotdog]

I have a 200 cylinder with the two top notches and the lug (3) but it has the inlet stud spacing of a 125-175 ! Would ii be correct in thinking this is a innocenti Lambro cylinder ?

[Adam_Winstone]

Sounds like it. I have a Lambro barrel that has the same characteristics; 66mm 200cc bore but 150 inlet stud spacing. Mine was fitted to a Series 3 import, many years ago.

The standard port timings are odd on these, for 3-wheeler use, so they pull ok low down but have a seriously poor ability to rev; great if you're carrying 20 sacks of potatoes or have a 25+ stone pillion.

[Hotdog]

Ok thanks, not a lot of good then unless I’ve go a Lambro !

[Warkton Tornado No.1]

Ok thanks, not a lot of good then unless I’ve go a Lambro !

Or porting knowledge & tools with a desire to prove success.....

[Adam_Winstone]

^... agreed. I revised the porting of mine to allow it to rev-on a little more. However, what I did note (from memory) was that the inlet port was very thin (low) and wide, and already beyond the duration of a TV200 barrel, which surprised me... and is not what I was expecting for a barrel that is intended to produce good power at low RPM.

... a dark art!

[Warkton Tornado No.1]

^... agreed. I revised the porting of mine to allow it to rev-on a little more. However, what I did note (from memory) was that the inlet port was very thin (low) and wide, and already beyond the duration of a TV200 barrel, which surprised me... and is not what I was expecting for a barrel that is intended to produce good power at low RPM.

... a dark art!

Interesting. Rumours were around decades ago that a successful Group Four racer used a Lambro barrel. I'm guessing now that it might have been used in conjunction with base packing to decrease inlet duration yet raise exhaust & transfer ports especially in the likelihood of being limited by the choice of pistons available for a 66 mmish bore.

That workaround could still apply, though personally i would never use a dedicated Lambretta piston when stronger, cheaper alternatives are available.

With a head let in to the bore & some relatively simple lowering of the transfer & exhaust ports to meet the piston crown height @ BDC, it could make for a very useable set-up

[Adam_Winstone]

^... yep, it certainly introduces a few more options.