MM Motorcycles

Today in Motorcycle History

MM Motorcycles


Nasce la Fabbrica Motociclette M.M.

La MM, Fabbrica Italiana Motociclette Morini di Mario Mazzetti e Alfonso Morini, apre un'officina in via Galliera 128. Mazzetti è un ex tecnico della G.D, Morini è costruttore e corridore in moto fin da ragazzo.

Nel 1927, con un modello da 125 cc guidato da Morini, la MM batte a Monza cinque primati mondiali di velocità. Lo stesso anno Amedeo Tigli vince il campionato italiano della classe 125 cc..

La ditta si afferma come la più temibile rivale della G.D in campo commerciale e sportivo. Il suo modello da 350 cc è adottato nel 1936 dal Corpo dei Vigili Urbani di Bologna, dalla Provincia e dalla Finanza.

Alla vigilia della guerra, nonostante Alfonso Morini nel 1937 se ne sia andato, la MM è la fabbrica di moto più grande della città.

Di lì a poco, tuttavia, è costretta a limitare la produzione ai motofurgoni. La fabbrica di via Calvaert, ricostruita in parte dopo i bombardamenti della seconda guerra mondiale, riprenderà con successo la produzione fino alla grave crisi del 1957, che coinvolgerà parecchie ditte meccaniche bolognesi.

Source: Biblioteca Salaborsa Licence: CC BY 4.0

A Brief History of the Marque

Manufactured in the years 1924 to 1957 at Via S. Serlio 5, and from 1930 at Via D. Calvart 42, Bologna.

The company was established by Mario Mazzetti (1895-1964), formerly of GD, along with Alfonso Morini (b.1898) and two financiers (Giuseppe Massi-Mazzi and Angelo Mattei) in 1924. Alfonso Morini raced an MM himself and won a class in the 1927 Italian Grand Prix at Monza. That year, the MM took five world records at Monza, and Amedeo Tigli won the Italian 125 Championship.

Mario Mazzetti è considerato una delle più illustri firme dell’industria motociclistica italiana, un tecnico illuminato, un costruttore animato dalla più intransigente scrupolosità che rasenta persino la più spietata autocritica. Uno di quei tecnici che consumano la loro vita tra regoli e compassi, attorno alle macchine d’officina, tecnici progettisti e costruttori che pagano di persona, mossi da una commovente passione per il mestiere, talché attraverso le loro mani il mestiere diventa arte.

Motociclismo, dicembre 1964 Motociclismo, dicembre 1964

Mario Mazzetti is considered one of the most illustrious names in the motorcycle industry, an enlightened technician, an animated builder with the most uncompromising attention to detail bordering on ruthless self-criticism. He is one of those technicians whose life is consumed working with slide rules and compasses, with workshop equipment, and with design engineers and builders; one moved by a passion for his craft, so that through their hands the craft becomes art."

Motociclismo, December 1964

The MM won numerous other races during the years 1925 to 1929, at which point the 125cc class ceased and a 175 category was introduced. A four-stroke 175cc machine was built to compete in this class, and this too was successful. At the time the 175 class was tax-free on the road, so it also did well commercially until 1933 when the rules changed, at which point MM introduced a 250cc road machine.

The 175 racers continued to impress for the remainder of the decade, winning world speed records and a 1/2 victory in the Italian Championship with riders Serafini and Bonazzi. Even Scuderia Ferrari campaigned with an MM.

A 350cc sidevalve machine was introduced and it too did well, winning major Italian endurance races in 1939 and 1940 and taking a medal in the 500 class of the International Six Day competition. This machine became the official Bologna police motorcycle in 1936 and MM machines remained in official service, apparently, until 1960.

A 500cc version was introduced in 1934, and both the 350 and 500cc SV machines were produced until 1950.

By 1939 the factory was the largest in Bologna, producing around 400 motorcycles per annum with sixty employees.

During the war they were forced to produce aeroplane parts, and were authorized only to build three-wheelers and to perform repairs on military vehicles. In 1943 the factory was destroyed by allied bombs - the war was not kind to MM, which had already suffered financially due to Mazzetti's vocal opposition to Mussolini.

Post-war the company produced a very fast 250 OHC model which sported rear suspension and Italy's first example of telescopic front forks, and this was soon joined by a 350 version. The 250 was as fast as the 500cc Gilera Saturno, whilst the 350 was good for almost 150 km/h.

By 1954 the 250 sported swingarm suspension with hydraulic dampers, a twin-loop cradle frame reminiscent of the featherbed, and a dual seat. There were few other motorcycles on Italian roads which could see it off, no matter the capacity.

Sadly, the market for such machines was fast shrinking, sales fell sharply, and despite the introduction of smaller, budget-priced 125cc motorcycles, MM closed the doors in 1957.

Mazzetti died in Bologna on 25 October 1964.

1. In 1937, Alfonso Morini left MM and established his own company ( Moto Morini ) producing motorized tricycles (a motorcycle chassis, engine and front end with two wheels at the rear). MM has been referred to as being from the initials of Mazzetti & Morini, but this is not so.
2. Nunzia Manicardi has published a book on Mario Mazzetti.
3. An exhibition of the works of Mazzetti took place at Museo del Patrimonio Industriale in 2009/2010 which included sixteen of his motorcycles. Details here: Mario Mazzetti Exhibition

Sources:, Tragatsch p211, Musei Patrimonio Industriale,,, Biblioteca Salaborsa, et al

MM Models

MM Monza 1927

  • Engine: Horizontal 2-stroke single. Bore 52, stroke 58, capacity 123.1 cc
    Ignition: Bosch magneto
    Carburettor: Amac
    Lubrication: petrol-oil mixture
    Primary transmission: gears
    Gearbox: 2-speed
    Final drive: chain
    Chassis: Double cradle, steel tubes
    Wheels: tyres 26x2
    Maximum speed: 95-100 km/h
MM 175 A Sport 1931

  • Engine: OHV Twin-port vertical with cast iron barrel and head. Bore 60.0 mm, stroke 60.0 mm. Capacity 169.6cc.
    Ignition: Bosch magneto
    Carburettor: Amal
    Lubrication: dry sump with double action MM oil pump
    Primary drive: chain
    Clutch: 2-plate
    Gearbox: Burman 3-speed, hand change
    Final drive: chain
    Frame: open, steel tubing
    Front suspension girder forks
    Tyres: 3.00x19 (3.50x19 sometimes fitted)
    Brakes: lateral expanding type
    Maximum speed: 90 km/h

MM 350 Corsa 1938

  • Engine: OHC vertical single, cast iron body and head. Bore 76.0, stroke 76.0. capacity 344.7 cc.
    Ignition: Bosch magneto
    Carburettor: Amal
    Primary drive: Chain
    Multiple plate dry disk clutch
    Gearbox: 4-speed Sturmey Archer, foot shift
    Final drive: chain
    Frame: cradle type, steel tube
    Front suspension: parallelogram fork
    Rear suspension: shock absorbers
    Wheels: front tyre 2.75 x 21, rear 3.00 x 20
    Brakes: Amadori with Elektron drums
    Maximum speed 175 km/h

1947 Models

  • Model 47A Sport 247cc
    Model 47C Turismo 350cc SV
    Model 47D Turismo 500cc SV
    Model 42D Motocarro 500cc SV

gquarta49 at
MM 350 47C
I am looking fo a COZETTE 22 carburator for my MM 350 47C, can anybody help?
Thank you
giorgio quarta
Lecce (Italy)
mic.bertoni at
MM 175 A 1933
Hello, I'm about to acquire a 1933 MM 175 A, is there any MM owners Club to refer to for a tech manual or support? I live in Italy. Thanks.
Michele Bertoni
Pisa, Italy
paulacme123 at
MM ? 1941?
Hi, I just bought this MM 350 as a 1941 bike but I suspect it's a later model due to its telescopic forks and Bosch coil ignition.
Can anyone out there please identify it more precisely and/or put me in touch with an owners group or possible supplier(s) of parts.
I'm based in the UK, Midlands, but do regularly travel to Italy.
Thanks in anticipation
Paul Mason

  • MM-1941c-350cc-PMa image posted to Comments.

Sat Jan 09 2016
jennklym at
1939 MM 500cc Italian racing bike
MM 500cc
Good evening!
I inherited this bike, and am trying to find any information and the current value. I was not sure how to add to the forum or FB, so any help you can give would be appreciated! Thank you!!
Winnipeg, Canada

Fri Jul 16 2010
pyoung<at>14engineering dot com<
MM 1909 MM
I have posted an article about Mr Rodriguez on my site here: gottfried-rodriguez-around-the-world

I found a bit of info about him on the internet, but there isn't much that has been documented after he left the USA.


(This MM is actually by Marsh Metz, made in Brockton Massachussetts, unrelated to the Italian firm. Great story!)

Fri Oct 09 2009
1wetdog at
mm motorcycle 350cc
any info on this machine as i am trying to restore one, call 07970 563935 or email
(see previous email below)

Thu Nov 13 2008 at
Moto MM
I'm an italian likers of bikes MM and I buy all MM materials (bikes, engine, parts, ..). My blog is: (404)
Italy (Bologna)

Tue Nov 11 2008
ittsuapizza at
I'd like to know about .my father's BIKE which name is MM.250cc. built arround 1960. It's still possible to drive after the light tuning.
Please let me know how much worth for money.

The page on Classic Motorcycle Valuations may prove helpful.

Wed Oct 22 2008
peter at
Handbuch von Motor und gesamten Motorrad
Motto MM 350 C Bj 1934-1938
Habe eine motto MM Bj 1935-1938 restauriert
Habe jetzt probleme mit der Motoreistellung, Startet gut und läuft im standgas auch gut. bei zunehmender gas aufnahme regelt der motor ab und hat keine leistung.
frage: Welcher vergaser ist fÃ&frac14;r dieses modell am besten und haben sie unterlagen dafÃ&frac14;r. haben sie auch dafÃ&frac14;r unterlagen zur einstellung der ZÃ&frac14;ndung

Mon Jun 25 2007
lammem at portup dot com<
1909 MM motorcycle
MM motorcycle 1909
I have a postcard with Gottfried Rodriguez on the front on an MM motorcycle stating he rode it around the world but can find no info on either him or the cycle, any clues? The postcard is also autographed by him in Toledo, Ohio
United States

Mon Jun 04 2007
jindrich.calta at
MM motorcycle
I'd like to identify the engine on the added photos. I have got a historic motorbike disjointed in parts and I don't know what is it. It was made about 1940, has 500ccm and there is logo MM on the engine. I'm going to construct it but I dont know how it looks.
I'm looking for some documents and photos of the old motorbikes made by M.M. Can you help me please or advise where can I get some information about M.M.?
Czech Republic, Havlickuv Brod

Thank you. I have found what I had been looking for. The model was made by MM in 1939.
I have recievd several photos from Mr. Giampaolo Tozzi from Bologna (His wifes' father made this motorcycles) and I'would like to share them.

Jindrich Calta

Tue May 30 2006
1wetdog at
MM 350cc Blackburn [Blackburne]
any information on this motorcycle would be nice in assisting with restoration has 350cc blackburn engine fitted very nice velose foot change on albion gear box , which model and which year would be a help thanks will post photos later
MM i think later to become moto morini
which year did MM fit a 350cc Blackburne engine in there bikes I have one and whish to restore it thanks
birmingham, england

Wed Apr 05 2006
jamescastleuk at
1950s MM 250 parts
MM 250 - 1950s
Hello there, I have a number of parts in excellent condition for an MM250 that a friend of mine rebuilt a decade ago and has since sold. I have photogaphed these scarce parts and lsited them on ebay and there is no interest which is surprising. I wonder if you could put me in touch with owner's clubs in the USA, UK and Italy. best wishes, James Castle

Tue Jan 31 2006
jindrich.calta at
I have got an old motorbike disjointed in parts and I don't know what is it. It was made about 1940, has 500ccm and there is logo MM on the engine. I'd like to construct it but I dont know how it looks. I'd like to see some documents and photos of the old motorbikes made by M.M. Can you help me please and advise where can I get some information about M.M.?