Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/126430
Before you sync, take these three basic steps This is the first ma series ofarticles by mstructors ofMotorcycle Mechanics at Los Angeles Trade- Technical College. Becawe "live" warll is tallen in as part of the training for third and fourth semester students, they have current llnowletlge of problems encountered by ewtomers. Many ewtomers prefer to do their own maintenance and tune-up. These articles wiU give some insight on the problems most often found, some of which are very difficult to locate without having had some actual e%perience. By Pat Owens Since the introduction of the four-cylinder road bike in 1969 - as a standard rather than a rarity - we find many times that any engine problem is blamed on carburetion adjustment and synchronization. . Many owners feel that merely adjusting and synchronizing the carburetors will solve their pro- Don't WII8te your time end bucks on carb synchronization before performIng these three simple melntenanc:e steps: ,(top to bottoml Dreln the fIoatbowls, looking 'or dirt end wllt8r; teat your wires end sperk plug caps; chenge aperk po..II8, being sure to remove old plug weshera from tho.. herd-to-reIIch middle cylinders. 22 blems; they feel this one step is the major pan of an engine tune-up. The fact of the matter is, that water in the carburetors as a result of the local car wash is the most common reason for carburetors causing poor running. In the course of a tune-up, carburetion adjustment and synchronization are done as the last step. Prior to any carburetor adjustment and synchronization. the following items should be checked and adjusted: (1) Battery; (l!) Compression on each cylinder; (5) Camchain tension; (4) Valve adjustment; (5) Contact breaker points for wear and the lubrication of rubbing block on battery ignition models; (6) Point gap or dwell on battery ignition models; (7) Timing using strobe light; (8) Air filter; (9) Gas filter at fuel valve. We now find three other areas left to be checked. and chances are you'll solve your problem in the process. Draining water and minor foreign \,Dalenal from most carburetors is simply a matter of shutting off the gas valve and loosening the carburetor drain screws on each individual carburetor. Usually a drain hOle leads from each carburetor to a mid point on the motorcycle behind the engine. If a piece of white paper is placed under these drain lines it is pretty easy to see if din and water has been drained from the carburetor float bowls. On bikes fitted with Mikuni carburetors, the paper must be placed directly under each carburetor as their drain lines are not connected to the drain screw outlet. that misfire under Engines acceleration or at high speed are often found to have defective high-tension spark plug wires. defective spark plug terminal or defective spark plugs. Staning at the ignition coil. determine if the spark plug wire is plugged in tight and is free from corrosion and carbon as a result of arcing. If the end of the spark plug wire is black from arcing, it should be shortened to eliminate the burnt end, the exposed coil of wire cleaned. and a new terminal end fitted. The inside of the coitshould also be cleaned. Before plugging the wire back into the coil, the wire' itself should be checked with an ohmmeter for resistance up to the end fitted to the spark plug cap. There should be zero resistance in the wire. Motorcycles come equipped with resistor spark plug caps. The standard resistance is usually between 6.000 to a maximum limit of 1l!.000 ohms. With age the resistance will increase, and this is a major cause of engine misfire on older motorcycles. In addition to increased resistance. these caps will sometimes develop cracks or carbon tracks which can allow the coil voltage to jump to an external ground instead of firing the spark plug. A close visual inspection will often allow you to see the cracks and carbon track deposits. Before installing spark plugs. check that all old spark plug gaskets are removed from the cavities in the cylinder head. A magnet on a flexextension has retrieved as many as three per cavity from the center cylinders on 750cc Hondas. Lastly, a visual inspection of a spark plug is a very poor way of determining its ability to fire a compression mixture in a running engine. The only good method is by using a spark plug machine which can put the plug under pressure with compressed air and fire it at the same time. Because -many road bikes are fitted with CB radio. we have found the new Cham pion resistor type spark plug to be a good replacement. On a recent trip to Oregon. a Gold Wing owner told us that not only did fitting resistor spark plugs help his CB radio interference, but also resulted in a five mpg fuel increasel