Home- Velocity/Engine Speed Programme
- Example
- Benelli Gentleman - std cylinder and carb
- Benelli Gentleman - Engine Specs
- Benelli Gentleman - Dyno Testing
- Benelli Gentleman - Fuel consumption Tests
Velocity/Engine Speed Programme - Benelli Gentleman/G2
The Velocity programme allows the user to either calculate the velocity at a given engine speed or calculate the engine speed for a given velocity for a Benelli Gentleman or a Benelli G2.
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Example
Suppose you have a Benelli Gentleman in original condition. Your top speed on the flat is 45 km/hr on 12/37 gearing and the tyres are 2.25" wide. Simply enter this information into the program and select the engine speed radio button. Now enter 45 into the velocity box and hit the Calculate button. The calculated engine speed is 6,058 revs/min.
Benelli Gentleman - mid 60's model
Shown below is a mid 60's Benelli Gentleman. This is the PS version with a single speed air-cooled engine and a claimed top speed of 28 mph. The engine has a single exhaust port, 2 transfer ports and a piston controlled inlet port. Induction is via a 12mm dellorto carburettor with adjustable air correction.
The bike weighs 41 kg dry and has 16" wheels with 2.25" tyres. One interesting feature of the engine is that the primary transmission is via gears necessitating a backwards turning engine. A wet clutch is fitted to the crankshaft. The engine has no internal gears and thus no oil.
Benelli - Engine Specs
The table below shows the Port Durations for this totally original piston ported intake engine. The cast iron cylinder has 2 transfer ports, 1 exhaust port and 1 inlet port. It is immediately apparent that the exhaust port timing is quite mild at 128.3 deg dur.
| Port | Duration (deg) | |
|---|---|---|
| Exhaust | 128.3 | |
| Transfer | 97.62 | |
| Inlet | 107 | |
| Bore | 40.0 | |
|---|---|---|
| Stroke | 39.0 | |
| Comp Ratio | 8.5 | |
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Benelli - Dyno Tests
Shown below is the measured power (hp) vs road speed (mph) at the rear wheel for a standard 1967 bike with 2,400 miles on the clock. The peak power of 1.39 hp occurs at 22.9 mph ( 36.6 km/hr ) and an engine speed of 4,900 revs/min. Top speed tests on a flat road resulted in an average top speed of 27.5 mph (44 km/hr).
The Benelli Gentleman has a nice flat power output with greater than 1.2 hp measured at dyno wheel between 13.8 mph ( 22 km/hr ) and 25.3 mph ( 40.5 km/hr ).
Benelli - Fuel Consumption Tests
The table below shows the measured fuel consumption - in both mpg (imperial) and l/100km - for a Benelli 210 at different throttle settings. The test course was 30.4 km long over undulating terrain. Fully kitted inc helmet etc, the test rider weighed 77 kg.
The optimum throttle position was found to be 1/2 throttle, resulting in a fuel consumption of 1.60 l/100km ( 177 mpg imp).
| Throttle | Consumption | ||
|---|---|---|---|
| Gearing | MPG | l/100km | |
| 1/2 throttle | 13/51 | 177 | 1.60 |
| 3/4 throttle | 13/51 | 171 | 1.65 |
| full throttle | 13/51 | 167 | 1.69 |
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