ASTM D4857 Standard Test Method for Determination of the Ability of Lubricants to Minimize Ring Sticking and Piston Deposits in Two-Stroke-Cycle Gasoline Engines Other Than Outboards
6. Apparatus
6.1 Test Engine and Stand:
6.1.1 Test Engine - A Yamaha RD-350B 347 cm3 twin cylinder motorcycle engine with attached standard transmission (gearbox) is used. The engine is described more fully in Annex A1. It is set up on a dynamometer test stand with a modified fuel system so that each of the cylinders is supplied independently through its associated carburetor. A typical test stand is shown in Fig. 1. The dynamometer is located to the left of the engine behind the instrument cabinet, and is driven by the motorcycle transmission output shaft.

6.1.2 Lubrication System - The test engine, as manufactured, is provided with an oil injection system by which oil is metered to the carburetor bowls from a common source. Because the test is run using a different fuel and oil mixture in each carburetor, the oil pump and its connections shall be removed and the oil connections to the carburetors plugged.

6.1.3 Dynamometer - The dynamometer shall be capable of absorbing at least 8 kW (10 hp). The engine crankshaft speed is 6000 r/min, and the motorcycle transmission may be used to provide speed reduction. No correction is required for the power loss in the transmission.

6.1.4 Cooling Air - A variable delivery blower with a free flow capacity of about 300 m3/min (10 000 ft3/min) of air is required. The flow from the blower shall be directed toward the exhaust side of the engine so as to deliver an approximately equal stream to each cylinder, and is varied as required to maintain the spark plug gasket temperature within the limits specified in Section 9. It is advised that the blower be set up to draw its air from outside the building. Where this is not practicable, or in hot climates, coolers may be required.

6.1.5 Combustion Air - The air supply to the engine may be taken from the ambient air in the test cell, but if a controlled air source is used, it is recommended that it be set to 25 to 27°C (77 to 81°F) with a moisture content of 11 to 12 g/kg (77 to 83 grains/lb) of dry air and a maximum pressure at the carburetor inlet of 3.7 kPa (1.5 in. water). Supply to each carburetor shall be through a separate flowmeter each with a capacity of 30 kg/h (65 lb/h) minimum. A plenum chamber is provided at the intake of each carburetor to damp out pulsations. These are shown in Fig. 1.

6.1.6 Fuel System:
6.1.6.1 Fuel is supplied to each of the carburetors by an individual electric fuel pump with a capacity of at least 2.5 L/h (0.7 gal/h) taking the fuel mix from separate tanks through a paper or ceramic filter and a flowmeter as specified in 6.1.6.2. The fuel shall enter the carburetors at a maximum temperature of 25°C (77°F) and cooling may be required in a hot climate.

6.1.6.2 Two flowmeters, one for each carburetor, are required. Any type accurate to +/- 0.01 kg/h (+/- 0.02 lb/h) at the flow rate specified in 6.1.6.1 may be used, but those measuring weight directly rather than volume are preferred. If a volume measuring device is used, the relationship of density to temperature over the range of fuel temperature experienced shall be determined for the actual test gasoline and test oil mixtures used, and the appropriate value used for conversion of volume to mass.

6.1.6.3 When permitted by local regulations, the use of portable containers with a capacity of at least 60 L (15 U.S. gal) is recommended to facilitate changing of fuels. If the fuel lines to the carburetors cannot be replaced when the fuel and oil mixture is changed, it is necessary to be able to purge the fuel system between the tanks and the carburetors.

6.1.7 Exhaust System - The standard motorcycle exhaust system shall be used, discharging into a pipe of at least 200-mm (8-in.) internal diameter leading out of the test cell. No modification other than axial rotation may be made to the exhaust system as supplied by Yamaha except the installation of thermocouples as specified in 6.2.4. Any rotation of the exhaust system shall be the same for both cylinders and shall not place the exhaust in the cooling air stream.

6.2 Instrumentation:
6.2.1 Tachometer - An electronic or vibration tachometer accurate to +/- 25 r/min.

6.2.2 Measurement of Ambient Conditions - If the air supply to the engine is taken from a controlled source, references to ambient pressure, temperature and humidity apply to the air from the controlled source.
6.2.2.1 Temperature - A thermocouple or thermometer shall be provided to measure air temperature in the range from 10 to 50°C (50 to 120°F). The overall accuracy of temperature measurement, including that of recorders, if used, shall be within +/- 1°C (2°F).

6.2.2.2 Barometric Pressure - A barometer measuring the pressure in the test room is required. Its overall accuracy, including recorder, if used, shall be within +/- 0.1 kPa (0.75 mmHg).

6.2.2.3 Humidity - A hygrometer accurate to +/- 3 % or a wet and dry bulb thermometer accurate to +/- 1°C (2°F) is also required.

6.2.2.4 Recorder - Continuous recording of the ambient conditions is recommended.

6.2.3 Spark Plug Gasket Temperature Measurement:
6.2.3.1 Thermocouples - The composite gasket normally supplied with the spark plug is not satisfactory for the attachment of thermocouple wires. A design that has been found satisfactory is given in Appendix X1. Provision shall be made for shutdown of the engine in the case of a spark plug gasket temperature increase of 10°C (18°F) or more. An automatic shutdown that operates if such an increase occurs is preferred. As a minimum, an alarm shall be provided to operate after a temperature increase of 6 to 7°C (11 to 13°F) to allow manual shut down by the operator if the 10° limit is exceeded. If the alarm or shutdown is a separate instrument from the temperature recorder, it is usually necessary to provide two thermocouples as shown in Appendix X1, but if it is incorporated into the recorder, only one thermocouple is required. Glass or silica double and constantan thermocouple wires meeting the requirements of Type J of ANSI Specification MC 96.1 (summarized very briefly in Specification E 230) are normally satisfactory. Constantan is an alloy of approximately 40 % nickel (Ni) 60 % copper (Cu) by mass.

6.2.4 Exhaust Temperature - A thermocouple is required in each exhaust elbow within 75 mm (3 in.) of the cylinder exhaust port to monitor exhaust temperature. The junction of the thermocouple shall be at the center of the pipe within +/- 3 mm (0.12 in.).

6.2.5 Temperature Recorder:
6.2.5.1 Plug Gasket and Exhaust Temperatures - These temperatures shall be recorded continuously. Maximum interval between successive recordings of the spark plug gasket temperature should not exceed 2 s, and 10 s for the exhaust temperature. A recorder with a range from 40 to 750°C (100 to 1400°F) accurate to +/- 2°C (4°F) is suitable.

6.2.5.2 Temperature of the Air Supplied to the Engine - This is preferably recorded continuously. In any case it shall be logged at intervals of not more than 30 min.

6.2.6 Pressure and Humidity of the Air Supplied to the Engine - The air pressure and humidity shall be logged at intervals of not more than 30 min.

7. Materials and Reagents
7.1 Test Fuel:
7.1.1 Phillips J is the preferred test fuel.

7.1.2 About 225 L (60 gal) of test fuel are required for a complete test following the standard procedure of two runs with interchange of oils between cylinders.

7.2 Reference Oils:
7.2.1 Benchmark Reference Oil - ASTM Reference Oil 606 is the benchmark reference oil for this test. About 6 L (1.6 gal) are required for a complete test (two evaluation runs), mixed with the fuel at the specified ratio.

7.2.2 Cylinder Calibration Oil - A calibration run is required on a new or fully rebuilt engine and at intervals as specified in 9.1. Use ASTM Reference Oil 606 in both cylinders. Six litres (1.6 gal) are required for the run. This oil's properties are summarized in Annex A2.

7.3 Stoddard Solvent - Hydrocarbon solvent meeting the requirements of Specification D235, Type I.

7.4 Thread Lubricant - Use an antiseize compound.

7.5 Gasket Sealer - Use a non-setting type to facilitate disassembly.

7.6 Cleaning Pads and Brushes - For cleaning engine parts for re-use, when this is permitted, scouring pads and brushes have been found to be satisfactory.