All models covered in this book are equipped with an air-cooled, 4-stroke, single cylinder engine with a single overhead camshaft.
The crankshaft is supported by 2 main ball bearings. The camshaft is chain-driven from the timing sprocket on the left-hand side of the crankshaft and operates rocker arms that are individually adjustable.
Engine lubrication is by wet sump with the oil pump located on the right-hand side of the engine next to the clutch. The oil pump delivers oil under pressure throughout the engine and is driven by the primary drive gear on the crankshaft.
This chapter contains information for removal, inspection, service and reassembly of the engine. Although the clutch and the transmission are located within the engine they are covered in Chapter Five to simplify this material.
Ignition system and alternator components are covered in Chapter Seven.
Before beginning work, re-read Chapter One of this book. You will do a better job with this information fresh in your mind.
Engine specifications and tightening torques are in Table 1 and Table 2 at the end of this chapter.
ENGINE PRINCIPLES
Figure 1 explains how the engine works. This will be helpful when troubleshooting or repairing the engine.
ENGINE COOLING
Cooling is provided by air passing over the cooling fins on the engine cylinder head and cylinder. It is very important to keep these fins free from buildup of dirt, oil, grease and other foreign matter. Brush out the fins with a whisk broom or small stiff paint brush.
CAUTION: Remember, these fins are thin in order to dissipate heat and may be damaged if struck too hard.
CRANKCASE ASSEMBLY
Apply assembly oil to the inner race of all bearings in both crankcase halves.
NOTE: Set the left-hand and crankcase half on wood blocks or a wood holding fixture.
Install the kickstarter assembly as described in this chapter.
Install the transmission assemblies, shift shafts and shift drum in the left-hand crankcase half and lightly oil all shaft ends. Refer to Chapter Five for the correct procedure.
Install the cam chain into the chain cavity in the left-hand crankcase half. Open the lower end up so the crankshaft will pass through it (Figure 79).
