Motom 48 4-Stroke Carburetors: Complete List of Models and Original Settings

Motom 48 Carburetors: From Weber to Dell'Orto

Two brands of carburetors were installed on the Motom 48 4T mopeds: Weber and Dell'Orto. Not all models had a single supplier: some—such as the 48 LL, the 48 GG, and the 51—left the factory with one or the other depending on the year of production. The data provided here comes directly from the original Owner’s and Maintenance Manuals and the Dell’Orto calibration catalog from July 1959.

Why Weber first, then Dell'Orto?

It’s no coincidence: when Motom was founded in 1947, Weber was already the go-to supplier for small Italian 4-stroke engines. The same 9mm carburetor powered the Cucciolo SIATA-Ducati, the only other significant 4-stroke micro-engine of the time. A natural choice, not a calculated one.

The SO Dell'Orto was introduced in 1950 as the first carburetor designed specifically for small 4-stroke engines ranging from 40 to 75 cc. In the 1950s, Ducati, Laverda, Parilla, Pegaso, Nassetti, and Somaschini—all of Motom’s direct competitors—gradually adopted it. Motom came later, between 1957 and 1958. Understandable: who would switch from an established supplier without a concrete reason?

There was a reason for it. The SO is technically superior to the Weber that preceded it: a more stable idle, more linear adjustment, and a more modern design. The Weber on the first Motomic from 1947 was a carburetor from the 1940s—robust, tried and true, but a relic of another era.

Weber carburetors

Type	Speaker	Jet nozzle	Min. flow rate	Max. flow rate	Float	Models
14 MF	9	150	40	55	5 g	Motomic 12 / 12A / 12C
14 MFM	9	150	45	62	5 g	12/D · 12/E
14 MFM	9	150	45	60	5 g	12/E UV · 48E
14 MFM 1	10	150	45	60	5 g	48L · 48S · 48LL
14 MFM 2	10	150	50	57	4 g (with a pin)	48LL · 48GG · 51

Weber's notes:

The 14 MF was equipped with a sleeve connection and a small-diameter air intake, featuring a filter screen without metal mesh.
The first version of the 12/D was equipped with the same carburetor as the previous models (14 MF), but with a flanged mounting featuring holes for studs and a screw-on filter element.

Dell'Orto Carburetors

Type	Speaker	Jet nozzle	Min. flow rate	Max. flow rate	Float	Models
Sun, Sept. 14	9	130	35	56	5 g	48 weeks · 48 days · 51
Sat, Dec. 14	12	130	35	70	5 g	48 SS
SH 9/14	9	130	33	57	5 g	48 Code
SH 9/14/2	9	130	33	57	5 g	48 UV Code
SH 9/14/3	8?	130	33	52	5 g	48 Woman
SH 12/14	12	130	35	56	5 g	'60 S · 48 SS
SH 12/14/2	12	130	33	62	5 g	'60 S · 48 Cross · 48 Junior

Dell'Orto SO and SH: What's the difference?

You can spot the SO model at a glance: the spray head is located outside the basin. You can clean or replace it without taking anything apart—a practical and elegant solution that is no longer available in the SH series. The reason for this change is not documented. If you know why, please leave a comment.

The models in the SH series are distinguished primarily by the number of screws used to secure the housing: the /2 version has one additional screw compared to the base model. It’s nothing revolutionary—but it’s important to know when you’re looking for gaskets or need to perform maintenance.

Endnotes

The data presented here was taken from the Owner's and Maintenance Manuals for the various specific models and from the Dell'Orto calibration catalog dated July 1959. For models equipped with both Weber and Dell'Orto carburetors, the specific type depends on the year of manufacture —

The 8-inch speaker on the SH 14/9/3 is listed as such in the original source: the question mark was already present in the Motom technical appendix, likely indicating that the information was uncertain even at the time.