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 f mail received, we cannot return any personal replies. Please limit your "Service" letters to technical subjects only, and keep them as briefas possible. Send them to: "Service," CYCLE WORLD, 1499 Monrovia Ave., Newport Beach, Calif. 92663.
BELT-DRIVEN SIDECAR
I ride a 750 Honda and on occasion I pull a Watsonian side car. The problem is this combination tends to shorten the chain life drastically. In your Sept. issue an article about the new Harley mentioned that several manufacturers make belt drives to replace chains. Could you give me your opinion of this hookup for my 750 with the side car? Also the names of some dealers that may handle the belt kits.
Clark Wroten Ramona, Calif.
We don't know of anyone who makes a final belt drive for a Honda 750 or any of the other big Japanese bikes. Most of the kits now available are primary drive out fits for Harleys and British Twins. Side car rigs often have chain problems because the side car demands lower gearing and owners install a smaller countershaft sprocket, which accelerates chain wear. If your 750 is geared down, it's better to use a standard or larger countershafi sprocket and go to an even larger rear sprocket. If you've already tried that and chain wear is still a problem, a heavy duty chain kit may be the answer. Phantom Rider sells such a kit, using #630 chain, for $70.19. Their address is 3001 Red Hill Ave., Costa Mesa. Calif 92626
IDLE SPECULATION
I own a 1979 Yamaha XS11 standard and a 1977 Suzuki GS400 and am bothered by the different instructions I get regarding balancing the carburetors. Both service manuals say to balance the carbs with the engine at idle speed whereas the Yamaha dealer says to always balance them at the rpm most often used (i.e. 3500-4000). This seems to make sense, but then the carbs are considerably out of sync at idle. What would you recommend?
Also I am thinking of drilling holes in the air duct (going to the air filter) in hopes of making the air intake less restrictive. Would this hurt the engine in any way? Is it a waste of time?
David Mordoff Johnson City, N.Y.
Yamaha recommends balancing the carbs at idle (1000 rpm) on the XSll for a number of reasons. They say holding the engine at a steady 3500 to 4000 rpm long> enough to sync the carbs produces a dan gerous amount of heat in a stationary aircooled engine and could cause the exhaust pipe chrome to overheat and turn blue. Also, the airflow and mixture conditions of an engine under load differ greatly from those of an engine running on the centerstand with no load. The manifold vacuum with throttles closed at idle is also more sensitive to small changes in adjustment, making more accurate settings possible. Some manufacturers have found that cer tain multis perform better if the outer carbs are set a slightly higher manifold vacuum than the inner pair, and Suzuki, for instance, recommends this procedure for all their Fours. The adjustment is sup posed to be made at 1750 rpm, which is
also the rpm recommended for balancing the carbs on your GS400.
After setting the carbs at recommended idle speed, it is always a good idea to raise the rpm slightly by operating the throttle at the twist grip, checking that the vacuum gauges rise and fall in unison. This is to insure the throttles are still in sync when any slop in the linkage and/or cables is taken up.
Occasionally, drilling holes in the intake plumbing or otherwise reducing air box restrictions will produce an air flow and power improvement on some bikes. It has been our experience at the race track and drag strip, however, that the performance of most stock bikes is reduced by tampering with the air cleaner or air box
unless other changes, jetting, pipes, etc., are also made. In most cases a clean aiA filter provides the most significant per formance improvement you can make to a stock intake tract.
GEARING UP
Presently I am riding a fully dressed~ 1975 CB750 Honda with 8000 mi. I'm aver aging 33 mpg commuting and 45 mpg high way riding. I would like to improve on this. Can I change the final drive sprocket or the rear wheel sprocket to improve the mileage? I am informed by the local shop that only the rear sprocket can be changed4 due to lack of clearance in the case. The changing of the rear wheel sprocket was not recommended because it would be of a Smaller radius, creating more stress on the ,chain.
Erwin C. Stickley
El Reno, Okla.
Honda used two different countershaft sprockets on different models, an 18 and a 19-tooth. If yours is the 19 there’s no more '•room for extra teeth at the countershaft, but you can install a smaller rear sprocket. There is no significant stress problem with a smaller rear sprocket. Most of the load is carried at any given moment by a small number of teeth at the top of the driven sprocket, so going up or down a few teeth has little effect on chain wear. Very small countershaft sprockets, however, can inycrease chain wear because a smaller number of teeth with reduced leverage carry the load.
CHAIN LETTER
I can’t seem to find anyone who has put out any information on product testing of the permanently lubed chain. I would love not having to oil the monster every 300 mi. Do those that advertise “no lubrication” really work? There must be some catches; what are they? I really would love to see an answer.
Father J. Williamson Brown, Jr.
Frankfort, Ky.
We’ve used both permanently lubed ITring chains and conventional oil-as-you-go types for extended mileage on large displacement bikes and concluded the following: (l) A conventional chain, frequently oiled, will outlast an unoiled O-ring chain except in conditions of severe dust or sand. (2) An O-ring chain without added lubrication may be quite worn at 10,000 miles and still not fail, whereas a conventional chain can become dangerously worn in less than 1000 unlubricated miles. (3) An O-ring chain will outlast a conventional chain if both are lubed at regular intervals. And (4) a lubed O-ring chain will last longer than an O-ring chain given no additional lubrication.
In other words, we’ve had good luck with permanently lubed chains. Given occasional lubrication (with chain lube approved for ITring chains) they last longer, keep dirt out of> the rollers better, and suffer occasional ne glect without self-destructing. You can buy a permanently lubed chain and never oil it, but it will last longer if you do. Occasional lubrication will also prevent the 0-ring chain from rusting in wet weather.
BELT CONVERSION
I am in the market for another helmet. I would like to know the model of the Electro helmet worn by the rider on page 62 of the July 1980 issue and on page 55 of the August 1980 issue. I would also appreciate Electro’s address so I can write them for more information.
Also, is it possible to convert the chain driven KZ440-A1 to belt drive? Is it an expensive and/or complicated procedure?
Alan J. Okamura Waipahu, Hawaii
The helmet you mention is the Electro 3 Tour Series model. Their address is Electro Helmets, 7166 Laurel Cyn. Blvd., North Hollywood, Calif. 91605.
The KZ440-A1 (but not the BÍ) chain drive model can be converted to belt drive, though a few modifications are necessary. A few spots of metal on the engine case just behind the front sprocket have to be lightly ground away and the swing arm must be slightly dimpled with a hammer to clear the rear spocket. Otherwise the belt and its two sprockets will fit with no problem. Rear sprocket, part no. 42041-5001, costs $53.00 list; the front sprocket, part no. 13144-1035, lists for $20.00, and the belt, part no. 59011-1001, is $40.00. The conversion won’t work on the non-LTD wire wheeled BÍ model because of a difference in swing arm length.
PARTS UNKNOWN
Hope you can help with some information. Who is the U.S. distributor for Ducati parts? What place offers the best chance of getting parts for an old (1967 160cc) Ducati?
E.F. Magdarz Raleigh, N.C.
The U.S. Ducati distributor is Berliner Motor Corp., Railroad St. and Plant Rd., Hasbrouck Heights, N.J. 07604. If they don’t stock the parts you need, they may be able to direct you to a dealer who does.
Another good source of information and parts for older models is the Ducati International Owners Club, who for a $10.50 membership fee can fix you up with a club patch, decal and DIOC Newsletter which provides technical tips, product information, classified ads for parts and bikes, and general Ducati-related news. For membership or more information write: DIOC, Joe Eliel, Director, 1447 S.R. 84, Ft. Lauderdale, Fla. 33315.
BRIDGESTONE PARTS
At our newspaper we have a consumer action column, and we have a reader who is in need of parts for his Bridgestone motorcycle. We contacted the AMA who referred us to you. Can you please forward us any information you may have on this motorcycle as to how parts can be ordered if there still are parts available. Thank you for youT cooperation in this matter.
Martha Easter Charleston Daily Mail
Charleston, W. Va.
The only shop we know of with Bridgestone parts is Marsh Motorcycle Ctf* 36 N. Road, Warehouse Point, Conn. 06008. They don’t have everything, but the owner, Fred Marsh, says he’ll be happy to help if he can.
GS450 FORK TIP
Since you are looking for a cure to the GS450 forks (RX for the Run-Down Fork), the following is a quick and cheap fix.
When 40 weight oil wouldn’t provide enough control, I knew the damper orifices were way too large. I pulled the damper tubes out and welded all four of the holes closed. I filed the welds flush, drilled smaller holes and polished them smooth. I used 0.041 in. for the two top holes (down from the stock size of 0.157 in.) and 0.05% in. for the lower holes (down from 0.234 in.)
I used 150cc of 5-weight oil and preloaded the springs a minimum of 1 in.
This cure provides very firm damping/ which is excellent when used in conjunction with aftermarket shocks and K-81s. LeS§ enthusiastic riders could try holes one-third the stock size, varying oil weight to suit.
Woodrow L. Bolz Lewisville, N.C.
DELL'ORTO KNOWHOW
Although I like to work on my trusty ol^ 1974 Moto Morini, it never really screws up enough to get me any good at it. would like to tear down the two Dell’Orto 26 mm carbs and clean them up a bit, but don’t know zip about how they work. If you could connect me with anyone whà has access to diagrams, manuals, parts^ etc. for these carbs, I would be in your debt.
Garth Proctor Euclid, Ohio Tuning information and parts for the Dell’Orto are available from Ron Wood. He says he’ll be glad to help you with any problems or questions. His address is 755 W. 17th St., Unit D, Costa Mesa, Calif. 92627. Phone number is (714) 645-0393.
LIMITED CHANGES
I own a KZ550 LTD. It is a very nic^e bike but has a few minor problems, i would appreciate any advice you can give me.
1) I have changed the stock tires to
Dunlop K81 Mk.2s. Could you please tell me the proper tire pressure for the front and rear tires for one rider on mountain roads? *
2) In the May issue of Cycle World it says the KZ650 brake pads will work on the KZ550 model. But will they work on the KZ550 LTD model?
3) On the automatic chain tensioner one' of two springs has been recalled. Can you tell me which of the two springs was recalled?
Tim C. Marney San Jose, Calif.
If you are of average weight, in the 160 lb. range, we would recommend tire pressure of 29 psi front and 30 psi rear for the K81 Mk. 2s, looking for about a 3 psi rise when the tires are hot.
The KZ650 pads will fit both the KZ550 and the KZ550 LTD, but in either case the thin metal backing plate and the two rivets which hold it on must be ground off to, make the 650 pads fit. This is an easy job and takes only a couple of minutes.
The chain tensioner spring to replace is the outer one, which sits at a right angle tt> the cam chain, under a 17mm cap. The Kawasaki part number is 92081-1302.
DOT FLUID
I’m confused. The owner’s manual of my 1980 CB750F says to use only DOT 3 brake fluid, but I’ve read many article^ about how DOT 5 is so much better. I must point out that I roadrace and manyother racers have DOT 5 fluid in their bikes. My Clymer manual says any other fluid besides DOT 3 may vaporize.
T.J. Barfield Greenville, S.C^
When the owner’s manual says use only DOT 3, it means you should use no brake-* fluid lower than DOT 3 on the rating scale. DOT 3 fluid will work perfectly well in the 750F’s brake system without boiling or vaporizing, but may absorb some moisture from the air and should be bled and replaced at the intervals recommended in your owner’s manual. DOT 5 fluid offers an even higher boiling point for extreme service, such as racing, and will not absorb moisture which can boil under hard braking and cause sponginess in the brake lever. You can use DOT 5 fluid if you don’t mind the extra expense, or stay with thé* DOT 3 and change it at regular intervals or when you suspect water contamination. You should not, however, mix the two brake fluids.
