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Benelli Sei – First Production Motorcycle With 6 Cylinders

Mention 6 cylinders to most bikers and an image of the Honda CBX immediately pops into their head yet it was the Italian Benelli Sei that was actually the first sixer to hit the production line. 

Let’s take a look at this rare and much sought after classic from Italy.

The World’s First Six-Cylinder Motorcycle

Under the lead of new owner Alejandro de Tomaso, the aim of the game was to get new models out quickly to put the Benelli name back on track. 

The quickest and easiest way to do this was to take the format of a bike already out there and twist it. 

In this case, it was to use the Honda CB500 Four and turn it into a 750cc 6 cylinder. 

None of this is to say Tomaso didn’t have ambitions because it was in fact his main goal to produce the worlds first production six-cylinder motorcycle and bring it to market. The second goal in line was to make sure it was a motorcycle that would give a solid performance. 

By researching motorcycle engines he settled on the CB500 as being reliable and solid enough, while being equally capable of having the extra 2 cylinders worked onto the unit. 

The motor was all but identical aside from the extra two cylinders. Other small changes were the placement of the starter motor and alternator and the use of just three carbs. 

The Benelli Sei 750 was indeed the first production motorcycle with a six cylinder engine and Tomaso achieved his Benelli dream. 

First unveiled in 1972, the Benelli Sei (six) didn’t actually leave the factory until 1974. 

Benelli 750 Sei Review

Benelli had picked a solid engine for the new model and then improved upon it, so Benelli were confident in the new design. 

The extra cylinders and overall engine design was lauded at the time as a feat of engineering and considered very impressive out of the Italian factory. 

It could produce 71 horsepower at 8,500rpm and had a top speed of 118mph, these figures were impressive by anyone’s standards and the performance was exactly what Tomaso had wanted to achieve. 

The three carbs kept the overall width down of the engine unit, paired with the upright seating position; this meant the rider had more room for their knees. 

Mid-range torque is where the 750 Sei excelled, with plenty of get up and go after 2,000rpm in top gear. 

Power delivery was smooth and consistent and while the models top speed wasn’t mind-blowing it was certainly up there, and the bike had an ability to cruise at high speeds all day long which is where it was most impressive amongst the competition. 

In terms of the chassis, it was a conventional design but one that worked better than most of the same era and it complimented the engine’s strengths as a result. 

The steel-twin cradle frame, Marzocchi forks and twin rear shocks were typical of Italian sporting motorcycles of the time. It was a strong rigid frame that made for great stability at speed.

Despite its size and weight the bike was considered to be fairly agile and would corner better than some of the smaller capacity machines around. 

Brembo front disc brakes provided the stopping power along with a rear drum. 

It was a handsome bike with styling from Carrozzeria Ghia who are best known for designing cars for Alfa Romeo, Fiat and Lancia. 

Tomaso had just sold his shares in Ghia prior to buying Benelli but the relationship was still strong enough to use them for his motorcycle ambitions.

Where the Benelli 750 Sei fell short was in it’s sales figures. 

It wasn’t the hit Tomaso had hoped for, the price tag was high, reliability was questioned by the public and running costs were feared. Largely though, it was down to the fact it just wasn’t as exciting as some of the other motorcycles of the day – most notably, the high performance Kawasaki Z1 900 and its Italian competitors, the MV Agusta 750 S and the Ducati Super Sport.

Any issues that did crop up were addressed with the second edition the Series 2 which ran from 1976 until 1978. 

Just over 3,000 units were made in the end before production ceased. 

Benelli 750 Sei Specs

Engine and Transmission

  • Engine – Transverse 6-cylinder, four-stroke, SOHC, 2 valves per cylinder
  • Capacity – 748cc
  • Bore x Stroke -56 x 50.6mm
  • Compression Ratio – 9.8:1
  • Cooling System – Air-cooled
  • Starting – Electric and Kick-Start
  • Transmission – 5 Speed
  • Induction – 3 x 24mm Dell’Orto carburetors
  • Final Drive – Chain
  • Max Power – 71 horsepower

Chassis and Dimensions

  • Frame – Steel twin-cradle frame
  • Front Suspension – Marzocchi telescopic forks
  • Rear Suspension – Dual Sebac shocks
  • Front Brakes – 2 x 300mm, 2 piston calipers
  • Rear Brakes – 200mm drum
  • Dry Weight – 220kg
  • Fuel Capacity – 16.5L

Benelli Sei 900 Review

For 1978 the bigger 900 Benelli Sei replaced the 750. 

The motor was bored and stroked to be 906cc. 

It ended up being wider than the 750, largely down to the alternator being repositioned to the side of the crankshaft. 

A rear disc replaced the drum brake and a new six-into-two exhaust system replaced the original 750’s six-into-six system. 

Power was up to 80 horsepower but the top speed was less than the original 750 at 99.8mph. This can be attributed to the extra pounds gained from being the bigger bike. 

The new bike handled just as well as its predecessor with responsive steering, stability at speed, good cornering and quality braking power. 

Again it wasn’t going to set the world on fire in terms of performance compared to the competition but the way the bike rode made up for any shortcomings. 

Four series of the 900 Sei were produced up until 1989 when production ceased, with a total of around 1900 units. 

Benelli SEI 900 Specs

Engine and Transmission

  • Engine – Transverse 6-cylinder, four-stroke, SOHC, 2 valves per cylinder
  • Capacity – 906cc
  • Bore x Stroke – 60 x 53.4mm
  • Compression Ratio – 9.5:1
  • Cooling System – Air-cooled
  • Starting – Electric and Kick-Start
  • Transmission – 5 Speed, wet clutch
  • Induction – 3 x 24mm Dell’Orto carburetors
  • Final Drive – Chain
  • Max Power – 80 horsepower

Chassis and Dimensions

  • Frame – Steel twin-cradle frame
  • Front Suspension – Marzocchi telescopic forks
  • Rear Suspension – Dual Sebac shocks
  • Front Brakes – 2 x 294mm, 2 piston calipers
  • Rear Brakes – 255mm disc, 1 piston caliper
  • Dry Weight – 254kg
  • Fuel Capacity – 16.5L

Why the Benelli Sei is a Great Classic Bike Investment

In recent years there has been a resurgence in motorcycle classics with the Benelli’s becoming popular among collectors. 

The prestige of the Benelli Sei being the world’s first production motorcycle with six cylinders has put it in good stead to be coveted by those who appreciate the history. 

With only around 3,000 750cc units produced and under 2,000 900cc’s, they are rare and there aren’t all that many still left in excellent condition. Those that do come up for sale tend to be snapped up quickly.

Motorcycle Finder has one for sale at £15,000. This seems to be the average price to pick up a 750 Benelli Sei in Europe. 

In terms of the 900 Benelli Sei, prices seem to be around £17,000. 

In the US prices are at the $16,000 mark for both versions. 

Another reason the Benelli Sei is a great investment is because at the moment those that are available are priced fairly and come in less than bikes from other Italian marques like Ducati and Moto Guzzi from the same time period. 

Both Benelli Sei are worthy motorcycle classics that are still in the buy to ride price bracket – for now.

History of Benelli Motorcycles

The story of Benelli goes way back to 1911 when six brothers came together to build a business invested in by their widowed Mother. 

Initially the small company was just a service garage where some car and motorcycle parts started to be produced. It wasn’t long before the brothers dream of building motorcycles would come to fruition.

In 1921 the first Benelli motorcycle appeared in the form of the Velomotore, a 98cc two-stroke. 

Benelli would see many successes in the early days before the Pesaro factory being bombed in WWII just when the Italian company was at the peak of it’s production capability. 

As with many manufacturers, post-war Benelli would go through some turmoil for many years and in 1971 Benelli along with Moto Guzzi were acquired by an Argentine car designer and entrepreneur named Alejandro de Tomaso. 

Alejandro de Tomaso wanted new models introduced asap and that is how the Benelli Sei came to be.

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