ASTM D4863 Standard Test Method for Determination of Lubricity of Two-Stroke-Cycle Gasoline Engine Lubricants
6. Apparatus
6.1 Test Engine and Stand:
6.1.1 Test Engine Configuration - A Yamaha CE-50 49 cm3 loop-scavenged air-cooled two-stroke-cycle engine is used. This has 40 mm (1.57 in.) bore, 39.2 mm (1.54 in.) stroke, with an aluminum piston operating in a cast iron cylinder bore. The cylinder head is removable, with a hemispherical combustion chamber. Further details are given in Annex A1. For the purposes of this test the standard piston-to-bore clearance is increased as specified in 6.1.2. The engine is no longer produced. Small quantities of parts can be obtained through Yamaha dealers. Special arrangements must be made through Yamaha for the production of large quantities of test parts.

NOTE 2 - The engine designation normally includes a final letter indicating the model, such as CE-50S, the model on which this test was developed. If this model is not available check the suitability for this test of available models with the manufacturer.

6.1.2 Adjustment of Piston Clearance - For the purposes of this test method, the cylinder bore shall be honed to give a 0.10 to 0.13 mm (0.004 to 0.005 in.) piston skirt diametral clearance with a 0.45 to 0.7 µm (18 to 28 µin.) arithmetic mean roughness finish, as specified in A3.4. It is recommended that a number of cylinders be honed out as it is normally necessary to use a new piston for each test and a new cylinder after every three tests. The modified cylinders shall be clearly marked as such.
(1) The power and specific fuel consumption curves at 500 r/min intervals over the range from 3000 to 6000 r/min.

(2) The spark plug gasket temperatures for each point of the power curve.

(3) Modified piston clearance, with measurements of the piston and cylinder bore dimensions. Additional modified piston and cylinder assemblies can also be supplied.

(4) Measurements of the piston rings, ring grooves, ring clearances, and ring gaps.

6.2 Test Stand - The dynamometer shall be able to absorb 2.5 kW (3.3 hp) at 4000 r/min with an inherent torque measurement accuracy of +/-0.5 % or better, and be capable of maintaining 4000 +/- 30 r/min with varying power input. A direct shaft drive or a belt drive from the engine crankshaft may be used. A complete test stand assembly, as shown in Fig.1, is available.

6.3 Cooling Blower - The original internal engine fan shall be removed or have its blades machined off. A variable delivery blower with a free flow capacity of about 34 m3/min (1200 ft3/min) of air is recommended. The flow from the blower shall be directed toward the intake side of the engine, as may be seen in Fig. 1.

6.4 Fuel System - Quick disconnects or other means to facilitate rapid interchange of fuel supply shall be provided as near to the carburetor as practicable. When local regulations permit their use, outboard portable fuel tanks of about 20 to 25 L (5 to 6 gal) capacity and flexible fuel hoses are suitable. In any case three fuel sources will be needed for a test, one for the non-reference oil fuel mix, one for the reference oil fuel mix, and one supplying test gasoline only with no oil. The temperature of the fuel entering the carburetor shall not exceed 25°C (77°F), and this may require cooling in hot climates.

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

6.5.2 Measurement of Ambient Conditions - It is assumed in this section that the engine draws ambient air from the test room. If it is supplied with air from a controlled source, references to ambient temperature, pressure and humidity apply to the air from the controlled source.
6.5.2.1 Temperature - A thermocouple or thermometer shall be provided to read air temperature in the range 10 to 50°C (50 to 120°F). The overall accuracy of temperature measurement, including that of recorders, shall be within +/-1°C (2°F).

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

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

6.5.2.4 Calibration - Calibrate the tachometer, ambient temperature, and pressure measurement devices every 90 days. The calibration standard shall be traceable to NIST.

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

6.5.3 Engine and System Temperatures:
6.5.3.1 Spark Plug Gasket Temperature - The spark plug gasket may be fitted with one or two thermocouples, the number depending on the instrumentation used. A design that has been found satisfactory is described in Appendix X1.

6.5.3.2 Exhaust Temperature - A thermocouple is required in the exhaust elbow within approximately 65 mm (2.5 in.) from the cylinder exhaust port to monitor exhaust temperature. The thermocouple junction shall be located within +/-3 mm (0.12 in.) of the center of the pipe.

6.5.3.3 Spark Plug Gasket and Exhaust Temperature Recorders - These temperatures shall be recorded using a system capable of storing the data for later retrieval. Maximum interval between successive recordings of the spark plug gasket temperature shall not exceed 1 s, those of the exhaust temperature should not exceed 10 s. A recorder with a range of 40 to 750°C (100 to 1400°F) and an overall accuracy of +/-1°C (2°F) is suitable. An alarm or automatic shut-down device may be provided.

6.5.3.4 Calibration - Calibrate the exhaust and spark plug gasket temperature measurement devices every 90 days. The calibration standard shall be traceable to NIST.

7. Materials and Reagents
7.1 Test Fuel:
7.1.1 Phillips J is the preferred test fuel. It consists essentially of hydrocarbons and contains trace amounts only of lead.

7.1.2 If Phillips J is not available, use gasoline containing 0.013 g/L (0.05 g/gal) maximum of lead, free of non-lead metallic antiknock additives and oxygenated blending components such as alcohols or ethers, with a minimum Motor Octane number of 82 as determined by Test Method D2700 or D2885 and otherwise conforming to the requirements of Specification D439 Class A or Class B. It may contain conventional anticorrosion, anti-icing, and so forth, additives and oxidation inhibitors in normal concentration. Any such alternative gasoline shall be tested by the procedure of 9.6 before it is adopted as a test fuel as it has been found that adequate differentiation between reference oils cannot be obtained with some fuels, some as isooctane, that otherwise meet the requirements of this section.

7.1.3 About 72 L (19 gal) of fuel are required for a complete test, including 15 L (4 gal) for the break-in.

7.2 Reference Oils - ASTM 604 and 602 reference oils are used for calibration purposes. ASTM 600 reference oil is used for break-in and as an assembly lubricant, and can be specified as the benchmark reference oil. About 0.4 L (0.1 gal) of each reference oil is required to run a calibration test, and 0.4 L (0.1 gal) of 600 for a break-in. The properties of these oils are summarized in Annex A2.

7.3 Non-reference Oil - About 0.4 L (0.1 gal) is required for a test. At least twice this amount should be provided in case the test is rerun.