xi Ignition Problems and Troubleshooting . . . . . . . . . . . . . . 217 Engine Does Not Start, Starting Diffi culty. . . . . . . . . . . . . . . . 217 Poor Running at Low Speed . . . . . . . . . 218 Poor Running or No Power at High Speed . . . . . . . . . . . . . . . . . . 218 Troubleshooting Procedures and Techniques . . . . . . . . . . . . . . . 219 Chapter 11 Lubrication Systems . . . 223 Friction and Lubricant . . . . . . . . . . 223 Oil Functions . . . . . . . . . . . . . . . . . . . .224 Oil Types . . . . . . . . . . . . . . . . . . . . . . .225 Additives . . . . . . . . . . . . . . . . . . . . . . .226 JASO, API, and SAE Oil Classifi cations . . . . . . . . . . . . . . .227 Two-Stroke Engine Lubrication. . . 228 Premixed Lubrication . . . . . . . . . . . . . .228 Oil Injection Lubrication . . . . . . . . . . . .230 Oil Injection System Maintenance . . . . .231 Primary Drive and Gearbox Lubrication . . . . . . . . . . . . . . . . . . . .233 Four-Stroke Engine Lubrication. . . . . . . . . . . . . . . . . . . 233 Dry Sump Lubrication . . . . . . . . . . . . . .233 Wet Sump Lubrication. . . . . . . . . . . . . .234 Common Sump Lubrication. . . . . . . . . .235 Oil Pump Types. . . . . . . . . . . . . . . . . . .235 Check Valves . . . . . . . . . . . . . . . . . . . .237 Relief Valves. . . . . . . . . . . . . . . . . . . . .237 Oil Filters . . . . . . . . . . . . . . . . . . . . . . .238 Oil Cooler. . . . . . . . . . . . . . . . . . . . . . .238 Lubrication System Maintenance . . . . . . . . . . . . . . . . . 239 Checking Oil Levels. . . . . . . . . . . . . . . .239 Leak Inspection . . . . . . . . . . . . . . . . . .240 Changing Oil and Filter . . . . . . . . . . . . .240 Oil Pressure Check . . . . . . . . . . . . . . . .242 Troubleshooting Lubrication Systems . . . . . . . . . . . . . . . . . . . . . . 242 Two-Stroke Engines Premixed Lubrication System . . . . . . . . . . . . . .242 Two-Stroke Engines with Oil Injection Lubrication System . . . . . . . . . . . . . .243 Four-Stroke Engines . . . . . . . . . . . . . . .243 Chapter 12 Cooling Systems . . . . . . . 247 Air-Cooled Engines . . . . . . . . . . . . . 247 Liquid-Cooled Engines . . . . . . . . . . 248 Liquid-Cooled System Components . . . . . . . . . . . . . . . . . . 248 Coolant . . . . . . . . . . . . . . . . . . . . . . . .250 Radiator . . . . . . . . . . . . . . . . . . . . . . . .250 Recovery Tank . . . . . . . . . . . . . . . . . . .251 Radiator Cap . . . . . . . . . . . . . . . . . . . .251 Thermostat. . . . . . . . . . . . . . . . . . . . . .252 Water (Coolant) Pump . . . . . . . . . . . . .252 Cooling Fan . . . . . . . . . . . . . . . . . . . . .253 Hoses and Clamps . . . . . . . . . . . . . . . .254 Troubleshooting and Servicing Air-Cooled Systems . . . . . . . . . . . 254 Troubleshooting Liquid-Cooling Systems . . . . . . . . . . . . . . . . . . . . . . 255 Servicing Liquid-Cooling Systems . . . . . . . . . . . . . . . . . . . . . . 255 Coolant Check . . . . . . . . . . . . . . . . . . .255 Flushing the Cooling System . . . . . . . . .257 Testing the Radiator Cap . . . . . . . . . . . .257 Testing the Thermostat . . . . . . . . . . . . .257 Water Pump Service . . . . . . . . . . . . . . .258 Checking and Replacing Hoses . . . . . . .259