The Service Dept
THE SERVICE DEPT
SERVICE BOOK REVIEW
JODY NICHOLAS
This book isn’t intended to replace the workshop manual for a specific motorcycle, but study of it will make certain portions of a shop manual easier to understand.
The book is filled with many good illustrations and graphs, most of which are explained in detail, which is helpful to the beginning motorcyclist. An example is in the carburetion section where several brands and types of carburetors are discussed and compared, and five pages are devoted to illustrations and notes on the disassembly of an Amal concentric carburetor.
Other important sections of the mo (Continued on page 44)
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torcycle engine are also explored and explained. Of special interest is the section on motorcycle ignition systems, which schematically shows and in simple terms explains the workings and limitations of the most popular spark producing units found on today’s motorcycles.
A great deal of stress is made on the keeping of a tuning log book, and several of the book’s back pages are blank log sheets which can be filled in to record tuning progress.
Even though engine settings found in a motorcycle shop manual are recommended, they are not always optimum for the use the motorcycle will be put to. The author gives some hypothetical examples which make it easier for the reader to understand how to razor-tune his machine.
Some portions of the book go into considerable technical detail, but many of these sections may be glossed over because they are merely placed in the book to further help the interested reader really understand what is happening.
But many of the hints and tips found throughout the book will be of interest to every rider, no matter how experienced-simple things that are often overlooked can make a ride more enjoyable.
No matter how inexperienced or expert a motorcyclist is, there is information in Tuning for Performance which will be of benefit to him.-Jody Nicholas
CHAIN LIFE
Would you please clear up a question for me? It concerns the chain on my 750 Suzuki. I have had the bike for about six months, and have put 13,000 miles on it. After having gone through two chains and one set of sprockets, I decided to buy a chain other than Suzuki’s. (I followed directions on chain maintenance to the letter.)
I mentioned something to this effect at my dealer’s, at which time one of his mechanics lost his presence of mind. He claimed the Suzuki chain is the strongest on the market. He also said the press-fit type master links that Suzuki puts out are no good. (Why does Suzuki make them then?) The only logical statement he made was never put in a regular master link. On that I agreed.
It was my opinion that if I bought a Duckworth or Diamond chain, and used the Suzuki press fit link, that it would be as strong or stronger than the original Suzuki chain. Seeing that they all are 530 size chain, I can see no difference except that a $45 price for the Suzuki chain seems to be rather high. The Diamond and Duckworth chains run about $20. Since both Diamond and Duckworths are used on Harleys, they must be strong chains.
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Robert A. Loose Beaufort, N.C.
With any high performance motorcycle which is capable of developing as much torque as the Suzuki GT750, you can expect fairly rapid chain wear unless you ride extremely carefully and pay extremely close attention to the recommended chain maintenance schedule. You claim to have done this, but other factors such as improper chain alignment or tensioning might have been at fault.
Service personnel at U.S. Suzuki Motor Co. maintain that they have seen GT750 rear chains last 10,000 miles with scrupulously careful maintenance, and have seen other chains last a maximum of 3000 miles with little or no maintenance. In a couple of instances the battery overflow tube was installed incorrectly, dripping battery acid onto the chain, and these lasted only a few hundred miles.
Every chain which was available several months ago was sent to the Suzuki factory for evaluation and after testing them all the factory engineers went to DID, the largest chain manufacturer in Japan, and had them design a chain especially for the GT750. It’s called the Heavy Duty 50 S and is indeed a robust chain. The DID engineers also insist that the riveted master link be used, a practice which has been employed on racing motorcycles for some time.
It is conceivable that you might get satisfactory life from another brand of chain, but I don’t believe it would last as long as the original GT750 chain.
Many GT750 owners ignore the first part of the chain maintenance instructions: “wash and lubricate every 500 miles,” and merely squirt chain lubricant on right over the dirt. The dirty layer prevents the lubricant from finding its way down into the bearing surfaces where it is needed most. Highly stressed chains with insufficient lubrication don’t last very long. Be sure and use a chain cleaner before you lubricate your chain, and then ensure that you have adjusted the chain properly.
With motorcycles becoming more powerful each year, exposed chains will be requiring more and more attention
BLOWOUTS AT SPEED
I recently had an accident on my (Continued on page 50) Honda 450 due to a blowout of the rear tire while traveling at the speed of the traffic on Interstate 84. I had my helmet on, as did my girlfriend, but neither of us remember anything after the bike started fishtailing. I revisited the site, and figure I rode the unstable bike for 200 yd. until I was going slow enough to pull over and be past the guard rail. I don’t remember stopping the bike, but I must have because I have a dislocated shoulder. My girlfriend had a lacerated elbow, but we’re both OK. I only bent the handlebars and broke the headlight.
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I had the bike for only three weeks, but had driven a friend's bike frequently for a year, and a mini-bike I built for six years. Should I have been able to control the bike to a stop? What would be the proper technique? The steering damper on my bike was not working. Would that have helped the fish tailing? What exactly does a steering damper do?
Upon examining the tire I found no punctures, but the tube was blown in the familiar star pattern. I figure the tube failed. Some people have suggested I change tubes three times a year. Does this sound like a good idea? Have you ever heard of tubes just blowing? It seems to me that bigger tires would be more reliable. What size tires do they use on big racing bikes? Might I be better off with large racing tires, both from performance in everyday condi tions and reliability, but not necessarily wear or top speed points of view? -
Many people think I’m crazy for wanting to get on a bike again. I’m not scared, I like to ride and I’m confident in my ability to see potential danger, but I want to see the question rationally. Are there ways of setting up my bike so it handles better-specifically different forks, different rear shocks, different fork angle, different wheelbase, or disc brakes, particularly rear? I know some of these might be expensive, but I’m willing to spend some money if it avoids another accident.
Richard A. Booth, Jr.
Boston, Mass.
Blowouts on motorcycle tires while traveling at freeway speeds are quite rare if the tire isn’t worn so far that the inner cord is worn through, causing an abrasion of the inner tube.
Tread depth is a good indication of how much wear a motorcycle tire has had. If the depth of either of a motorcycle’s tires is in the region of 1/8 in. it’s time to replace that tire. Also important to high speed riding is the (Continued on page 52) tires’ inflation. Your owner’s manual gives details on how much air your tires require for high speed riding, either solo or carrying a passenger.
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Other telltale signs of impending tire failure are obvious external scuffs on the sides of the tires and less obvious fatigue marks which can only be seen from the inside and which look like bruises. These marks are usually made when an under-inflated tire hits a sharp object. Generally speaking, it’s better to run a tire with a little too much air in it than with too little air.
Riding techniques to be used with a tire blowout are a little difficult to set forth because of the many variables involved. If the blowout occurs while traveling in a straight line as yours did, it is best to keep the motorcycle as upright as possible and decelerate gently, using the brake on the wheel which is not flat. Hence you should have applied the front brake gradually and made an attempt to get out of the way of traffic as soon as practicle. Try not to ride over any bumps with a flat tire or you will almost assuredly get into a fishtail situation.
A steering damper is placed on a motorcycle to help keep the front wheel from being rapidly deflected sideways if an object is struck, and to lessen the effect of the oscillations a machine will sometimes get into at high speeds. If you were moving at the same speed as the rest of the traffic, you shouldn’t have needed to have your steering damper tightened at all.
New motorcycles are delivered from the factory with tires which have proven to give the best all around handling characteristics. Altering these sizes will not in most instances improve the handling characteristics of the motorcycle significantly. Most road racing tires are not recommended for street use because they are somewhat “triangular” in cross section, which affords the tire less adhesion with the ground when the machine is in a vertical attitude. These tires are also softer than a normal street tire and will wear out more quickly.
There are many different front fork and rear shock units available which are adaptable to many different motorcycles. However, the manufacturer has gone to great pains to design and produce units which are compatible with their products. Unless a great number of miles have been covered on a motorcycle, these units should be in good enough condition to keep from contributing significantly to a situation which could cause an accident. Good riding habits are the best things to use in the prevention of accidents.
