The Honda CB750 DOHC Four Repair Manual 1979-1982 by Clymer covers the following motorcycle models:
Book Excerpt: 1979-1982 Honda CB750 DOHC Four Repair Manual
- Honda CB750C Custom 1980-1982
- Honda CB750F Super Sport 1979-1982
- Honda CB750K 1979-1982
- Honda CB750K LTD 1979
Poor engine performance can be caused by any of a number of things related to carburetion, ignition, and the condition of the sliding and rotating components in the engine.
In addition, components such as brakes, clutch, and transmission can cause problems that seem to be related to engine performance, even when the engine is in top running condition.
Idling that is erratic, too high, or too low is most often caused by incorrect adjustment of the carburetor idle circuit. Also, a dirty air filter or an obstructed fuel tank vent can affect idle speed. Incorrect ignition timing or worn or faulty ignition components are also good possibilities.
First, make sure the air filter is clean and correctly installed. Then, adjust the throttle cable free play, the throttle stop screw, and the idle mixture air screw (Figure 6) as described in the routine maintenance chapter.
If idling is still poor, check the carburetor and manifold mounts for leaks; with the engine warmed up and running, spray WD-40 or a similar light lube around the flanges and joints of the carburetor and manifold (Figure 7).
Listen for changes in engine speed. If a leak is present, the idle speed will drop as the lube "plugs" the leak and then pick up again as it is drawn into the engine. Tighten the nuts and clamps and test again.
If a leak persists, check for a damaged gasket or a pinhole in the manifold. Minor leaks in manifold hoses can be repaired with silicone sealer, but if cracks or holes are extensive, the manifold should be replaced.
The carburetor assembly has to be removed and partially disassembled for this adjustment.
- Remove the carburetor assembly as described under Carburetor Removal/Installation in this chapter.
- Remove the screws (Figure 46) securing the float bowls to the main bodies and remove them. In order to use a float level gauge it is necessary to remove all float bowls for gauge clearance.
- Measure the distance from the bottom of the float to the float bowl gasket surface (Figure 47). The correct height is 0.61 in. (15.5 mm). Use a float level gauge as shown in Figure 48.
Subject: 1979, 1980, 1981, 1982 Honda CB750 service, maintenance, repair. ISBN-10: 0892873043 | ISBN-13: 9780892873043 | Clymer M337