The Honda XL75, XR75, XL80, XR80, XL100, XR100 Repair Manual 1975-1991 by Clymer covers the following models:

•  XL75 1977-1979
•  XR75 1975-1978
•  XL80S 1980-1985
•  XR80 1979-1984
•  XR80R 1985-1988, 1990-1991
•  XL100S 1979-1985
•  XR100 1981-1984
•  XR100R 1985-1991

NOTE: see the Clymer M222 shop manual for 1992-and-later Honda XR80R and XR100R models.

This Honda XR75 manual includes  information on the XR80 engine as well as the XL100S and XR100 engines. Replete with hundreds of photos and illustrations populating its 244 pages, the manual helps Honda motorcycle owners tackle engine issues like removal, inspection, service and reassembly, engine cooling, crankcase assembly and tips on how to become your own mechanic. This could save you hundreds or even thousands of dollars as you learn how to tend to matters concerning clutch and transmission, fuel and exhaust systems, ignition and cooling systems, front and rear suspension, brakes, body and frame and more. The Motor Bookstore will ship the manual free to the continental 48 United States, usually within one business day of receiving the order.
Book Excerpt: 1975-1991 Honda XL75, XR75, XL80, XR80, XL100, XR100 Repair Manual ENGINE

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

1. 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.
2. Install the kickstarter assembly as described in this chapter.
3. 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.
4. 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).

Subject: 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991 Honda XL75, XR75, XL80, XR80, XL100, XR100 service, maintenance, repair. ISBN-10: 1599693151 | ISBN-13: 9781599693156 | Clymer M312-14