Benelli Models 49 to 65 cc



1969 Benelli Parts Catalog Dynamo Compact 50cc Dynamo Trail 50cc Dynamo Woodsbike 50cc

1968-69 Dynamo

5. Benelli models with 4M, 4MS, 4M65 engines 1965-77

49 or 59cc vertical cylinder 4-speed foot-shift, manual clutch.

1960's Benelli 50cc 4-speed foot shift, "mild" version with Dellorto SHA carb

Left 4M, right 4MS, 16 intake

1969 Benelli Dynamo Trail 50 engine

4MS engine






4M engine: The 4M has a mild cylinder, with shorter and narrower ports, a 12mm ID intake, and a smaller 12mm Dellorto SHA 14/12 side-draft carburetor.

The 4M engine was on the 1968-69 Benelli Dynamo Compact. M means marce, Italian for “march”, or in the motorcycle industry “foot-shift”.

4MS engine: The 4MS has a “sport” cylinder, with taller and wider ports, a 16mm ID intake, and a larger 16mm Dellorto UA16S down-draft carburetor. Horsepower 4.5 at 7800 rpm. This is the version shown in the parts illustration.

The 4MS engine was on the 1965-68 Benelli Fireball and Fireball Trail, and 1969 Dynamo Trail and Super Mini.



Benelli 4M and 4MS engines





1972 Benelli Dynamo 65cc Parts Manual

1969-75 Dynamo



4M65 engine: Since 1970 the 4M and 4MS 49cc engine size was increased to an advertised 65cc on the 4M65. But the actually size was 59.3cc. Bore and stroke were 44 x 39 mm. That was dishonesty in labeling, motivated by “bigger is better” thinking.

The Benelli 4M65 engine is on 1971-73 Mini Enduro, 1970-72 Cougar, 1970-71 Dynamo Compact, Dynamo Trail (Scrambler), Woodsbike, 1972-73 Compact II, Dynamo II, Woods II, 1974-75 Dynamo Trail, 1976-77 Dynamo. It has large square head, larger piston, Dellorto ME15BS carburetor. 


1969-75+ Benelli 65cc 4-speed engine

Benelli 4M65 engine