The Service Dept

THE SERVICE DEPT

Len Vucci

If you have a question or comment of a technical nature, send it to us. We’ll attempt to answer as many letters as possible and we’ll publish those which we think are of interest to the majority of our readers. We’ll also print some helpful hints and how-to’s reflecting frequently asked questions. Technical correspondence should be sent to: Service Department, CYCLE WORLD, 1499 Monrovia Ave., Newport Beach, Calif. 92663.

OSMOTIC HYGIENE

Here’s an economical means of keeping a motorcycle’s running gear sparkling clean. An old paint brush, and a soupy mixture of ordinary modeling clay and water is all it takes.

For years I've been crumbling scrapped clay into water to produce a mixture about the consistency of mortar used in brick laying. The mixture should be thick enough to cling but at the same time liquid enough to be easily applied with the paint brush.

About once every two months I coat my Yamaha 360 and my son’s Honda CT90 wherever grease, road tar and traffic film have accumulated. Occasionally, I paint the entire bike, skipping only the saddle and tires.

The first coat should be applied between an eighth and a quarter of an inch thick, and will dry rapidly in the sunlight. As soon as the water has evaporated out of the clay, the hardened product begins acting like a sponge—soaking up most grease through the principle of osmosis. The process can easily be seen because sections of the even-colored clay turn dark as oil and grease are absorbed. If more is needed it is a simple matter to paint on an additional coat, of the same thickness, and repeat the procedure.

The clay should be left on the frame, engine, wheels and fenders overnight. When the clay has begun drying again, this time with grease and oil absorbed throughout its texture, it will usually flake for easy removal with an ordinary garden hose or at a self-service car wash. After washing, the clay again may leave a fine grayish film on some surfaces, particularly fenders, headlight, and chrome, but it wipes easily away with a clean cloth.

This simple process, repeated at frequent intervals, is all that is required to keep any bike clean year after year.

Robert Latimer Las Vegas, NV

EASY FIX

In the summer of 1975, my 1973 Norton 750 Mark V Commando was running great—until a four-wheeler ran a stop sign. I have reassembled the bike, after having the frame straightened by Kurt’s Frame Shop here in Pittsburgh. It’s running great again—no wobbles at any speed, but I am now plagued by an engine problem. The motor bogs when the throttle is snapped open. I notice this most when opening it from idle, but it is also evident in a high gear roll-on from 50 or so (3000-3500 rpm). The motor sat for a year, but I cleaned the carbs thoroughly. Do you think the 67 degree Magura throttle I installed is the culprit? Help!

Mike Davis Pittsburgh, Penn.

The Magura throttle might indeed be an indirect cause, but the symptom you describe seems to be normal operation!

If the throttle is snapped open—the Magura makes this easier—the suddenly large venturi area of the carburetor causes a drastic decrease in fuel mixture velocity. Consequently, carburetor vacuum and fuel flow also decrease, starving the engine of fuel. This will be especially noticeable at lower rpm and in higher gears.

Some carburetors use an accelerator pump to provide a squirt of raw gas to enrichen the mixture during sudden throttle opening. This is one expensive solution. We recommend merely rolling the throttle on more gradually, the cheapest solution of all.

ANOTHER LIGHT PROBLEM

I recently purchased a 1975 Honda CB360T. I like its riding quality and handling.

The problem I am having is in starting. So far I have had to have the battery charged twice (I use the starter motor a lot). After 85 miles, the stock plugs were so fouled there was no spark across the electrode. I then installed Champion N-3s but starting still seems far below my expectation.

I would be grateful for any advice.

Jack C. Burton Edgartown, Mass.

The problem you describe has been increasingly common since the introduction of non-switched headlights. The lights on most motorcycles draw nearly as much current as the charging system can supply. Little current is available to charge the battery, which can then be drained by frequent starter motor use.

The normal solution involves the installation of a switch in the lighting circuit. This allows the battery to receive an adequate charge during daytime bike use.

If by chance you are primarily a night rider, that fix is obviously not for you. Instead, purchase an inexpensive trickle charger and use it often. Or, use the bike's kickstarter.

NEED A LIGHT?

Many 12-volt road bikes with bulb/refiector-type headlights lend themselves well to an inexpensive conversion. If the original headlamp bulb is rated about 35 watts, the 40/50 watt standard automotive sealed beam can often be adapted to the stock headlight shell. The increased brightness and superior pattern of the sealed beam is a considerable improvement over most stockers.

Automotive sealed beams cost as little as $1.50 in many auto supply houses, and are available in two sizes.

Afier the original bulb/reflector assembly is removed, one of these sealed beams will often be a perfect fit. If not, a little scrounging through the local shop 's used parts bin should turn up a shell that is usable.

The dual filament (high/low beam) lamp has three lugs, arranged in a “U". The right leg of the U will be common or ground; the center lug is low beam; and the left leg is high beam. Crimp-type spade-connectors can be used after cutting off the original plug, making sealed beam replacement fairly easy.

Those late-model road machines already equipped with sealed beams can also use the inexpensive automotive type. I've seen prices at some motorcycle dealers which were closer to $10 than $5! Reasons offered were different beam pattern and current rating, and resistance to vibration and shock. While pattern and current draw might be slightly different, headlight standardization means any sealed beam will be entirely acceptable.

HONDA XL

I would like to pass on a tip I have learned on troubleshooting XL Hondas.

Often, a thorough tune-up including new plugs, points, and condensor fails to cure a misfiring problem. Indirectly caused by vibration, this might be the fault of either the ignition or kill switch.

Try disconnecting them, one at a time, and ride the bike. If the misfire disappears, replace the switch which was at fault.

Richard (Frenchy) Klimas Parkersburg, W. Va.