Home- Velocity/Engine Speed Programme
- Example
- Jawa 210 - std cylinder and carb
- Jawa 210 - Engine Specs
- Jawa 210 - Dyno Testing
- Jawa 210 - Fuel consumption Tests
Velocity/Engine Speed Programme - Jawa 210/207
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 jawa 210/207.
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Example
Suppose you have a Jawa 210 in original condition. Your top speed on the flat is 45 km/hr on 13/51 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 6,295 revs/min.
Jawa 210 - mid 90's model
Shown below is an early 90's Jawa 210. This is the 130 version with a single speed air-cooled engine and a claimed top speed of 30 mph. The engine has a single exhaust port, 4 transfer ports and a piston controlled inlet port. Induction is via a 12mm Jikov carburettor with adjustable air correction.
The bike has 16" wheels with 2.25" tyres. One interesting feature of the engine is that the primary transmission is via a flat toothed belt and a dry clutch is fitted to the crankshaft. The engine has no internal gears and thus no oil.
Jawa 210 - Engine Specs
The table below shows the Port Durations for this totally original piston ported intake engine. The alloy cylinder with a cast iron liner has 4 transfers and 1 exhaust port. It is immediately apparent that the exhaust port timing is quite mild at 135 deg dur.
| Port | Duration (deg) | |
|---|---|---|
| Exhaust | 135.06 | |
| Transfer | 101.36 | |
| Inlet | 119.72 | |
| Bore | 39.0 | |
|---|---|---|
| Stroke | 41.0 | |
| Comp Ratio | 9.0 | |
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Jawa 210 - Dyno Tests
Shown below is the measured power (hp) vs road speed (mph) at the rear wheel for a standard 1992 bike with 5 miles on the clock. The peak power of 1.4 hp occurs at 17.5 mph ( 28 km/hr ) and an engine speed of 4,000 revs/min. Top speed tests on a flat road resulted in an average top speed of 27.5 mph (44 km/hr).
Shown below is the same bike after it has been given a mild tune to increase the top speed of the bike - and hence cruising speed - plus faster hill climbing ability. The new peak power of 1.68 hp occurs at 19.8 mph ( 31.86 km/hr ) and an engine speed of 4,457 revs/min. The bike now has an average top speed of 31.5 mph (50 km/hr) on the flat, an increase of 4 mph.
At a speed of 19.8 mph with a 77 kG rider on board the bike can maintain this speed on a hill with a gradient of 9.3 %. The standard bike can only maintain this speed on a 6.6 % hill.
Jawa 210 - Fuel Consumption Tests
The table below shows the measured fuel consumption - in both mpg (imperial) and l/100km - for a Jawa 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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