Service
SERVICE
We welcome your technical questions and comments, and will publish those we think are oj interest to our readers. Because oj 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, Calij. 92663.
NEEDS AN ADVANCE
In the August, 1978 Cycle World KZ650SR test there was a comment on the lag just off idle on the 1977 Kawasaki 650s. I have an early KZ650C that has this annoying glitch. In the test, Cycle World fiddled with this problem until an advance curve from a KZ900 cured the glitch. Would you please comment on exactly what was done to clear the glitch?
Frank Draine Pennsauken, N.J.
The ignition advance mechanism was replaced with an advancer from a KZ900. Ignition timing on the KZ650 is controlled by points opened and closed by the points cam. The points cam is not mounted directly on the crankshaft, but is mounted on a centrifugal advance mechanism which is connected to the crank. You will have to remove the points backing plate to reach the advance mechanism, a minor job. Kawasaki part number 21148-010 is marked on the box our advancer came in.
RADIO NOISE
I have a 1973 CB750K2 with a Windjammer II fairing. I installed an AM-FM radio, which plays great until you start the engine. I guessed it was spark plugs, so I switched to resistor plugs and then resistor caps, but neither helped. I know the spark plug wires are solid rather than carbon, but
I can't change the wires unless I also change the coils. Have you any tips on installing radios?
Ed Whitaker Hot Springs, Mont.
Resistor caps and plugs will usually do the job, and when they don't the chances are changing the spark plugs wires wouldn 't ' help, either.
We’d guess your culprit is the antenna. If it’s too close to the engine, your radio will pick up electrical noise. Try mounting the antenna on the fairing, while keeping the. cable as short and as far from the engine as you can.
THREE’S A CROWD
I currently possess a slightly pregnant wife and an affectionate Yamaha RD350. used as a commuter and weekend tourer.Can I boost it to 400cc with parts from an RD400? Is this a sensible change? I want mufflers quieter than stock. What can I use? Will SuperTrapps do it?
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Finally, I'd like to attach a sidecar for the w ife. If I gear the bike for a top end of 65 or so. could I construct a sidecar to carry a 125 lb. wife? If so, w here can I get plans or share ideas?
Steve Savage University. Mass.
You can bore the 350 to nearly 400 ce, but because the factory did the enlargment with a stroke increase, 54mm to 62 mm, and made a series of other interna! changes, you can't use later parts unless you buy a complete engine. And because Yantaba saw fit to make a stronger drivetrain to go with the added displacement and torque, we'd suggest you keep the 350 as a 350.
Super Trapps will work fine. Try seven or eight discs for a start and juggle until you 've got the sound right. Also, be prepared to scrape out the carbon on a regular schedule.
A sidecar is not a good idea. We understand why you'd want to keep a prized scooter even though your family is growing. But. The RD350 is a super sports bike. The power band, the engine size, the geometry and suspension, even the size of the machine are as far from optimum for sidehack hauling as it's possible for a motorcycle to be. Keep the RD for solo and save up for a nice slogging four-stroke if you want the family car to have three wheels.
IDLE TOO LONG
My just-bought 1972 Suzuki TS125 has a small but annoying problem. The motor has a lag as soon as the throttle is opened. I've adjusted the carb. changed plugs, cleaned the filter, etc. The engine pulls strongly above 3500 rpm. This problem makes trail riding darned near impossible and right now I'm stumped.
R.L. Johnson Conneaut. Ohio
Your bike probably has more years than miles on it, that is, it may have spent a long lime just sitting idle. Check the carb for shellac or varnish on the slide and other internal parts. Then clean the pilot jet, needle jet, etc., with solvent. Your miss sounds like the engine is going too lean when the throttle is cracked.
Or it may be plugged with carbon. Near the end of your exhaust pipe is a #2 screw. Remove it, and take out the internal baffle. Clean the baffle and put it back—for forest legality and social conscience.
GOLD WING ON THREE
Your comments in the October issue about the 1978 GLIOOO interested me. I have one of the beasts, with 25.000 miles on it. The part about running on three cylinders got me. My bike does the same thing.
Larry Nattras Ocean Springs. Mass.
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Honda 's tech people say the cure is easy. The GL's carbs tend to collect sludge with the miles. Clean the vacuum pistons with solvent, contact cleaner or the like, and wipe them dry. Just in case, the spark plug the factory people are using is HD's X24ESU.
PARTS SOURCES
Can you help us with a problem? Our son has a Benelli, in excellent condition except for a few missing parts. Do you know where we can find them?
Jerome Garfoot Elroy. Wise.
Try Cosmopolitan Motors, Jacksonville and Meadowbrook Roads, Hatboro, Penn< ¡9040. They've been importing and distributing Benellis for years and usually have a complete stock of parts.
RICKMAN RESOURCE
However hard this is to believe. I have run across an interesting piece of maj ehinery: a Rickman Metisse with Zundapp 125 piston port engine. It’s equipped with a speedometer but lacks the headlight and taillight. I'd like to know w here I can get parts.
Roy Shiro Idabel. Okla.
Target Products, 2724 W. Main Street, Alhambra, Calif. 91801 is the place to go They have a complete stock of parts for the dirt Metisse models, 125 and 250, Mk. 3 and Mk. 4, as well as parts for the street and road-race Rickmans. They also import the current frame and suspension kits for Honda and Kawasaki engines and the Rickman line of race and touring fairings.
MORE PARTS
You surely remember the 125 MX DKW. the one with the famous false neutrals. I've had one since 1971. Problem is. how' can I get parts? Does Hercules still handle parts for us DKW owners?
Donald Clifton Fort Myers. Fla.
Hercules Dist., Ltd., 9825 Mason Ave., Chatsworth, Calif. 91311 has parts for Sachs and DKW, 1968 through 1974, 80, 100 and 125 cc, five and six speed, etc., along with other parts and even repair manuals.
You might also want to try Stormers, Ltd., 8410 Katella, Stanton, Calif. 90680>
THE SOURCE
The man who wanted a breakerless ignition for his BSA might like to know about a company with the best stock of Triumph and BSA parts I've found. It's GP Cycle Works. 4721 Telegraph Ave.. Oakland. Calif. 94609. They have parts from 1947 on and I've found them invaluable in working on my 1969 BSA Rocket Three.
Skip Lively Virginia Beach. Va.
SPROCKET SELECTION
I own a 1978 Kawasaki 650-B2 and would like to improve the gas mileage. Would it be better to fit a smaller rear sprocket or a larger front sprocket? And I'd like to find a happy medium between the 650's fine performance and getting lower rpm on the highway.
Frank Magli Grayslake. 111.
The answer depends on how much difference you want. Changing a rear sprocket enables you to make smalt changes of a tooth or two. A change of one tooth on the rear will he hardly noticeable on the 650 Kawasaki. A change of two teeth will he about a 5 percent change and a couple of hundred rpm at 60 mph. A change of three teeth on the rear sprocket works out about the same as a change of one tooth on the front sprocket.
Changing rear sprockets is usually more expensive than changing front sprockets because the rear sprockets are larger. They Just cost more. But rear sprockets wear faster than front sprockets and you're more likely to need a new rear sprocket than front sprocket. When your sprockets wear out. try a different size. If your sprockets shownoticeable wear; forming a cup-shaped surface on one side, or the chain has stretched nearly to its limits, it's a better idea to change both sprockets and the chain so the w orn pieces don 7 wear out the new pieces faster than they should. E3
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