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Phil Aysnley looks at a 1964 Benelli 250/4 Racer


Benelli’s first 250/four was the 1939 water-cooled supercharged machine that was obsolete after the post-war ban on forced induction – Benelli 250/4 Supercharged (link).

1964 Benelli Provini 250/4 Racer
1964 Benelli Provini 250/4 Racer

Ing. Savelli designed a new 250/4 that was first raced in 1962 and which was developed, through about a dozen examples (none of which were the same), into Kel Carruthers’ 1969 title winning bike. The 250/4 campaigned in the early ‘70s by Saarinen and Villa was a completely different design by Savelli’s sucessor Piero Prampolini.

1964 Benelli Provini 250/4 Racer
The 1964 Benelli Provini 250/4 Racer won the Spanish GP

1964 Benelli Provini 250/4 Racer
This example was displayed in the US at the Daytona Motor Show

This particular bike is Provini’s 1964 Spanish GP winning machine sent to the US for display at the Daytona Motor Show by the US importer Cosmopolitan Motors. It stayed in the US until it was bought by the current owner and exported to Spain) and is quite different to the original bike that was raced by Grassetti during ’62-63.

The two valves per head were set at 90º (later to 63º and then to four valves per cylinder) and a seven speed gearbox was commonly used (although five to eight speeds could be fitted).

1964 Benelli Provini 250/4 Racer
Early models were a two valve head

1964 Benelli Provini 250/4 Racer
Eventually four-valve heads would be used, with a seven speed gearbox the most common option

1964 Benelli Provini 250/4 Racer
The original four-coil ignition was soon replaced by a Lucas magneto, then a Mercury outboard item

The prototype had a dry sump with the oil tank fitted under the seat but this soon was changed to a bolt-on sump that held two litres. Likewise the original battery and four coil ignition was replaced first by a Lucas magneto, then in late ’64 by one out of a four cylinder Mercury outboard engine that could better handle the high revs.

1964 Benelli Provini 250/4 Racer
This bike is fitted with the 20mm carbs, probably for display in America

1964 Benelli Provini 250/4 Racer
Either 22 or 24mm items were used on later versions

The ’62 prototype used four 20mm carburettors, also fitted to this bike, no doubt before it was sent to the US, but later versions used either 24mm (more power) or 22mm (more torque).

1964 Benelli Provini 250/4 Racer
The initial 1962 model only boasted 36.5hp

1964 Benelli Provini 250/4 Racer
By 1964 this had risen to 45hp, with a 16-valve model making 55hp, but suffering from a narrow power band

Power of the ’62 bike was only 36.5hp at 12,500rpm but by ’64 it was up to 45hp at 14,500rpm, then 50hp at 15,000rpm from ’66 onwards. The later 16-valve motor made some 55hp at 16,000rpm but with a narrow power-band. A more torquey 12-valve (twin inlet/single exhaust) was also experimented with.

1964 Benelli Provini 250/4 Racer
A 12-valve motor was also experimented with

1964 Benelli Provini 250/4 Racer
This was the final of the drum brake models, before discs were adopted by Benelli

1964 Benelli Provini 250/4 Racer
1964 also saw a more modern chassis used

The ’62 bike’s frame was replaced by a more modern chassis in ’64 – still using Oldani drum brakes. Benelli was the first factory GP team to use disc brakes in ’65. This bike has the smaller 7.5 litre ‘short circuit’ tank fitted – a 9 litre tank was used for GPs.

1964 Benelli Provini 250/4 Racer
This model features a 7.5L tank (not fitted pictured) however a standard 9L option was normally used.

The diminutive size of the bike can be seen here!

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