Service
SERVICE
DEPARTMENTS
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.
GROUNDLESS STATOR
Last year I purchased a GS750 and have been very pleased with this motorcycle, but it has a flaw to which I would like to alert other owners. After only 6500 mi. my alternator stator burned out. The mechanic has informed me this is due to a poorly grounded battery box, battery and regulator-rectifier.
As I missed getting my bike in by only a couple weeks of the warranty date, I had to foot the bill, although it would seem to be a factory related problem. My particular dealer was very reasonable and understanding, but yours may not be. So I urge other owners of these motorcycles to have this checked and repaired if necessary, as this is an expensive repair if the bike is out of warranty.
Fred D. Willms Caldwell, Idaho
Suzuki’s tech people tell us they’ve had very few alternator or charging system problems on the GS750, and that the same system is used in the GS850 and 650. They
say that most stator failures result from damaged insulation on the stator windings, usually from a manufacturing defect, improper handling during installation or repair, or vibration against a mounting bolt or case cover. A bad ground on the regulator-rectifier will cause a slight increase in stator temperature, making damaged in-
sulation more likely to fail, but it shouldn’t create enough heat in itself to damage the stator. In the few cases where a stator has really been fried, the cause is generally a wiring harness short from the battery side of the regulator-rectifier, so that full battery voltage gets fed back through the stator to ground. Most grounding problems in the rectifier or battery merely lead to reduced charging capacity.
Frequent washing of the bike, damp air; vibration, age and the usual corrosion between bolted parts and electrical connectors can all cause poor grounding in the charging system, so it’s a good thing to check if any charging problems arise. In the ease of a relatively new GS, a bad ground may have aggravated a stator insulation problem that was already there.
MORE STATOR TROUBLE
I own a 1979 Yamaha SR500 with 12,220 mi. on it. One evening, after 1 tuned it to perfection, it failed to start>
after many kicks. The battery was charged, all wiring was clean, dry and properly connected. The spark plug was good.
Several other SR owners told me of a similar problem. They said after checking everything from fuel in the tank to tire pressure the problem was narrowed down to a faulty stator and/or silicon rectify, replaced at a cost of S240. This gave me indigestion. The bike has never been abused (i.e. run with no oil, given a full rev burnout IO sec. after starting, etc.).
What would cause such a catastrophe? Is there an inexpensive alternative? Is there any way to prevent it again? Plea.se help. I grow weary riding my 10-speed 24 mi. to school in the Portland rain.
Brian Manion
Portland, Ore.
The most common cause for the problem you describe is not in the stator itself w hich is a fairly reliable part of the system, but in the pulser coils attached to the stator. Disconnect the wire connectors between the pulser coils and the ignitor unit and use an ohm meter to test the resistance in the coils. Checking the resistance of the white/green wire to black you should get 87 ohms, -\—30 percent. Then check the white ! red wire to black and you should grf a resistance reading of 16 ohms, H—30 percent. If either circuit is bad, the pulser coils are out. Early Yamaha parts cards may not show' these as a separate part, but the unit part number is 2J28141 and the list price is $17.16 for a new’ set. There is no single reason for these parts to malfunction. other than those usual enemies of electrical components, heat and vibration, which can cause internal breaks in the wire w indings of the pulser coils.
Another, but much less common, cause for ignition failure on the SR and other big Singles is a sheared key in the keyway between the crank and the flywheel. Not likely, but it never hurts to check the easy things first.
OIL LEAK AMENDMENT
We reported in our May, ’82, Service column that leaking cam end plugs on Kawasaki 1000s could be cured by wrapping the plugs w ith seven layers of Teflon tape. Kawasaki Service Dept, has since provided us with some added information. The leaks, they say, occurred only on some ’81 1000s and 1100s, usually after the plugs had been removed during motorcycle servicing. Wrapping the plugs w ith Teflon tape w as a temporary fix for old plugs only. Plugs <W newer models and the replacement plugs now’ in stock are of a new design and should not be wrapped, as damage to the cylinder head could result. The new' plugs fit both the ’81 and ’82 models.
GPZ INJECTION FLOW
I own a lightly modified 1981 Kawasaki GPzl 100 and am trying to find a procedure to calibrate the analog fuel injection system. 1 have a shop manual, but it contains no precise information for this. The changes made in the bike are these: ( 1 ) a Kerker 4-into-l exhaust, (2) a K&N air filter has been installed, and (3) the air box cover has been modified by cutting the center out, leaving only the edge of the filter top to secure a tight fit for the filter itself, while reducing air flow restriction.
The dealers here only sell the bikes and none of their mechanics have any experience with the GPzl 100 fuel injection system. Any advice you could offer would be appreciated.
Claude Horner, Jr.
Mililani, Hawaii
The EFI system on the '81 GPzl 100 uses a trapdoor-type airflow meter on the intake to regulate fuel flow relative to the amount of air passing through the meter. There is enough latitude in the system as it comes from the factory to compensate for the changes you are making, so no adjustment or recalibration should be necessary.
LUBE AND OIL TIPS
A couple of hints you may want to pass along: When applying chain lube with a spray can it always seems to get where you don’t want it—even with the small nozzle, which always seems to get lost. 1 spray the chain lube in the can top and apply it to the chain with an acid brush. These are the metal handled brushes with about Vi in. stiff bristles, generally used for applying soldering paste flux. They sell for less than 15 cents at hardware stores.
Carrying oil on a trip: Phillips packages its Aviation oil in plastic containers with screw tops. The container is relatively flat and packs well. It also has a long spout which is handy for pouring. One could scrounge an empty one at an airport.
Robert L. Mann
Gothenburg, Neb.
A couple of the other oil companies, such as Bel-Ray and Chevron, are also selling motorcycle oil in jug-like plastic containers with caps now. Handy for people on the road who don’t like leaving messy half-quarts of oil behind at gas stations. The spouts on these are generally not as long as those on the av-oil cans, however, so people with hard-to-reach filler caps may find the aviation containers best. Reusing a plastic container is also a nice idea, of course, because (getting in our conservation licks here) the cheap, traditional paper and tin oil containers eventually melt away while plastic is on this earth forever. IS
