Service

SERVICE

We welcome your technical questions and comments, and will publish those we think are of interest to our readers. Because of the volume of mail received, we cannot return any personal replies. Please limit your “Service” letters to technical subjects only, and keep them as brief as possible. Send them to: “Service,” CYCLE WORLD, 1499 Monrovia Ave., Newport Beach, Calif. 92663.

MORE XS BLOWBY

I read with some amusement the letter in your Service column from Ronald Shortz (June ‘81) entitled the Oiled Filter. I too own a ‘78 Yamaha XS750E and experienced the same problem of blowby oil leaking out the airbox. However, a top end job every 20,000 mi. is really not a very practical solution. Instead, I merely installed an oil trap in the breather tube, using a small plastic bottle, cable tied to the rear of the engine, used the necessary fittings and added an extra length of breather tube from my friendly Yamaha dealer.

I must admit, though, that with 19,000 mi. on my bike my oil consumption is only about half of Mr. Shortz’, at half a quart every 500 mi. Still, I think this may be a useful suggestion for Yamaha owners, since they do all have this problem, as you pointed out. Dave B.asott.

GRAPHITE OIL

I own a 1978 Yamaha XS-400E, stock engine except for a J and R header system, ARC ignition and rejetted carbs. I asked everyone I thought might know if it would be safe to use ARCO graphite oil in my bike. Everyone said “maybe”, “don’t know”, etc. Five hundred miles ago I decided to try it. I have experienced no clutch problems whatsoever. I have tried to provoke slippage by slowing in top gear, pulling the clutch and revving the motor, then dumping it. It simply hasn’t affected the clutch, even after a long ride with the oil hot.

One thing that was affected was how my bike shifted. Missed shifts between 5th and 6th gears and general notchy shifting was the norm until I used ARCO. Now missed shifts are few and far between (most of the time it is now due to sloppiness on my part), and the shifting is very smooth. I can’t say what would hap-> pen in the clutch of a high-power bike like a GS or GPzllOO, as I don’t happen to have one right now (wait until next year!). If you happen to have one on hand wl\y don’t you try it and see.

Dave Hamblin

Cincinnati, Ohio

ARCO does not recommend using this oil in four-stroke engines with wet clutches because they haven’t tested its effects on the wide variety of clutch friction materials used. Also, most manufacturers will not warranty engines using graphite oils. For those reasons, and because most modern motorcycle engines provide an extremely long service life on bearings, rings, etc. (even under racing conditions) using conventional, less expensive multi-grade motor oils recommended by the manufac-* turers we’ve been able to see no clear advantage in using a graphite oil. Easiëï shifting, in your own case, may be a worthwhile advantage, especially if the clutch is working fine and the bike is off warranty anyway.

PHILLIPS BLUES

I’ve just tried to perform your suggested carb fix (Jan. and May 1981) on my GS550 and failed for a simple and embarrassing reason. Even with the help of Liquid Wrench and my K-Mart impact driver I wasn’t able to get the Phillips screws loo^p on the second carburetor I tackled. Is there a secret to loosening factory-tightened screws without butchering the slots? If so, let me in on it.

Incidentally, I restored the first carburetor to its original condition. I assume it’s not a good idea to run one carb richer than the others.

Bob Olmstead

Maywood, 111.

When a Phillips screw becomes really rounded out and you have a crater instead of slots, there is little recourse but to drill the screw out and retap the hole, or drill off the head, remove whatever the screw was holding, and unscrew the remaining shank with Vise-Grips. But before things get to that stage, a few other tips are worth trying First, make sure the Phillips screwdriver is the right shape and size for the screw; don’t use a #1 tip in a screw that will accept a #2. Cheaper screwdrivers, even if they are thy right size, often have pointed tips that keep the blades from nesting firmly in the screw; sharp tips should be ground off. Having found the right tip, be sure to exert solid pressure against the screw when you try to turn it. Phillips screwdrivers will try to cam out of the screw slots when turned, which h why most manufacturers use them in the first place—the screw head limits assembly torque and prevents snapped bolts.

If a screw resists loosening, try tightening it a little, then loosening again. Impact also helps loosen screws; a few sharp blows with afiiammer at the end of the screwdriver may jolt the threads loose. With an impact driver like yours it is important to have the right \fit, hold the driver handle firmly in the direction you want the screw to turn, and also to have the part held solidly, either on the bike or in a vise, so you can give the impact driver a good sharp rap with the hammer. Ôn a piece like a carburetor the rubber jnounting sleeves may soften the blow of the impact driver and prevent it from loosening Hie screw. It might be better to use a Phillips screwdriver with a square shank and turn it with a wrench while holding pressure against the heel of the screwdriver, or use a Phillips head socket with a ratchet and extension.

Hot and cold treatment sometimes helps With larger bolts. If you can heat the surrounding metal with a benzene torch, a soldering iron or welding torch (but don’t do this on your carb bodies!) it will expand foster than the bolt and make a looser fit for removal. In some cases it is possible also to cool the bolt with contact cleaner or a spray can with freon propellant, like aerosol lens cleaner.

In the case of your carb screws, if the screw heads are already stripped, the next step is probably to try gripping the screw heads with small Vise-Grips (use a small file to make square corners on the screw heads, if working space permits). If that doesn’t work, you’ll have to drill and retap. As one last hint, carbs are always easier to work on—and less likely to suffer stripped screws—if you take the extra time and effort to remove the carbs from the bike and fix them on your workbench. Screws will be easier to see and reach, and the carb bodies can be supported more securely. Small screwdrivers at wrong angles in awkward places are great for stripping screws.

BELT LUST

I lust for a belt drive on my Yamaha SR500E, similar to the one on the Kawasaki 440 LTD. Is it possible to adapt This type final drive to my Yamaha?

J.L. Blankenship

Angleton, Texas

We don’t know of anyone now supplying belt drive kits for the SR, so you and your focal machine shop will be on your own doing the conversion. If you adapt the belt drive sprockets mdke sure you have the right swing arm length and axle adjustment to allow the use of an existing belt, like the Kawasaki’s, as Gilmer-style belts •are still limited in application and aren’t available in a variety of sizes. >

BAJA ENTRY

I would like to know if I, as a man who has never raced before, can enter the Baÿi race? Do you have to be a member of the AMA? Please enlighten me as to registration, fees, and so forth.

Andrew Seymore Lockport, La.

The major Baja endurance races are sanctioned by an organization called Score International, which is not associated with the AMA. To race in the Baja 1000 you must be a member of Score. The annual^ membership fee is $25 and the address is Score International, 31332 Via Colinas,, Suite 103, Westlake Village, Calif. 91362. Membership will put you on their mailing list for bulletins of upcoming events. Entry fees for Baja vary from year to year, but a motorcycle entry with insurance fees and Baja municipality and state fees will run in the neighborhood of $370. Part of that money is used for a Baja improvement fund; roads, hospitals, etc.

Previous racing experience is not necessary in entering the Baja race, though riding experience and good physical condition are certainly assets for anyone who enters. Mechanical requirements for bikes entered, equipment carried, etc. differ from the rules in other off-road events, so a certain amount ofpreparation specifically for Baja is required. Score will fill you in on the details.

CZ SOURCE

I’m sure you are aware of Jawa CZ’s brilliant motocross achievements in the 1970s. I hope you can suggest several sources for parts, parts lists and manual^ for my ‘74 CZ 125. Are there dealers in the U.S. or Canada? Central parts warehouses? Tech reps?

Les Nordin Ottertail, Minn.

We know of two sources for Jawa CZ parts and information: Metropolitan Motors, 1661 Hyde Park Ave., Hyde^ Park, Mass. 02136 and Cycle Mechanix, 957 Washington St. Rt. 138, Stoughton^ Mass, 020272, (617) 344-7181. B