Service

SERVICE

JOE MINTON

Squealing CB750

I own a 1974 Honda CB750 with 7000 miles showing on the odometer. It is in mint condition and I am very fond of the bike, but it is plagued with a front brake that squeals horribly. The disc is not galled and the pads are new Honda metallics.

What is the cause and how can I prevent the noise?

Richard H. Wallace Groveland. California

Your problem is a common one, not only on the early Hondas but most other disc-brake-equipped bikes of that era. The squealing is due to what is called stick-slip vibration, the very thing that causes chalk to squeal so gratingly on a blackboard. The design solution has been to increase the stiff1 ness of the brake caliper and associated hardware, thus altering the natural vibration frequency of the brake-system components. These and other design developments have largely eliminated disc-brake squealing as a

problem during the past decade.

You can probably get rid of your bike's brake squeal by applying one of several anti-squeak compounds, available at auto-parts stores, to the backs of the pads. These compounds dampen

the vibration between the pads and caliper. If this doesn't do the job, change pads. Hard metallic pads are more prone to squealing than softer organic pads, which seldom present a squealing problem. >

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No time to ride

Last year I bought a new 1 986 Honda 700 Magna and I love it to bits. I'm busy during the week and only have time to ride it on weekends. Since the bike sits for five or six days at a time. I'm concerned about the gasoline leaving deposits, and about shortening the battery’s life. Also, for winter storage, my owner's manual states that I should change the oil and filter prior to storage.

And, even if the bike isn't run and it sits for more than four months, that the oil and filter should again be changed prior to riding it. Why is this?

Mike Kay

South Holland, Illinois

Letting a bike sit for five or six days does not const it me ",storage, "so you needn't worry about fuel deposits or the battery sulfat ing. But if the bike sits dormant for more than three weeks, the battery should be disconnected, serviced and then charged on a trickle charger for a couple of hours every two weeks.

I fa bike is stored where the temperature varies considerably, condensation inside the engine can occur that would contaminate the motor oil. But by changing the oil, you decrease the possibility of running the engine with impurities in it that may have accumulated through the storage period. AH of which could damage or shorten the life of the engine.

Custom crazy

I'm sure that you are aware of many motorcycle shops that customize Harley-Davidson motorcycles. But are there any shops that provide similar service, especially engine hop-up work, for Japanese cruiser-style machines?

I have a 1400 Suzuki Intruder with a Corbin seat, a Jardine exhaust system and some minor aftermarket bolt-ons. Aside from that. I’m lost.

James Christian Atascadero, California

You own a motorcycle that is technically and functionally superior to the Harley-Davidson Big Twins in most ways. However, it is inferior in one important way: It is not largely supported by the aftermarket.

Understand that many people buy Harleys because of the enormous aftermarket support that exists for the bikes. There are many of us (including major players within H-D itself) who believe that Harley would not have survived its troubles of the early '80s were it not for the American aftermarket.

One of the difficulties of rapid design change, something the Japanese are doing less and less of incidentally, is that a supporting aftermarket does not have time to develop before the bike disappears front a maker's lineup. The only Japanese motorcycles that have had long-term support in the aftermarket are those that make good drag racers. If you own an original Kawasaki Z-l or Suzuki G SI 100, you can buy all sorts of performance parts for them. That will never happen for your 1400 In truder.

Tingly Maxim

I recently purchased a 1 982 Yamaha Maxim 650 with 5000 miles on it. The bike runs great except for a vibration in the handlebars and footpegs just above 5000 rpm. Unfortunately, that’s the cruising rpm at 60-65 mph. A service shop told me this is normal for inline-Fours. Is there anything 1 can do to get rid of this? Is a gearing change possible to lower rpm at cruising speeds.

Larry Kaskel

Pacville, Maryland

AH inline-Fours have a second harmonic vibration that has roughly onefourth the energy and twice the frequency of the printary imbalance. The printary imbalance is canceled by the alternating motion of the pistons, and the secondary imbalance can be canceled with a counterbalancing shaft. Most inline-Fours aren't equipped with counterbalancers, and, as you /night expect, this is not something that one can bolt-on.

While you cannot redesign your engine, you can alter how its inherent vibration affects your bike and you. Following are some of the things that I have found to work. Be sure that the engine is properly tuned. Incorrect carburetor idle-mixture adjustments together with curbs that are not sychronized will greatly affect vibration. Loosen the engine-mounting bolts enough to let the engine move, run the engine at 4000 rpm or so (don't ride the bike!) for a few seconds, then retorque the bolts. Perhaps you can change the amount of vibration you feel by fitting different handgrips or foot peg rubbers.

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Since your Maxim is a shaft-drive motorcycle, you cannot realistically change its gearing beyond fitting a slightly larger diameter rear tire.

Smoke signals

1 recently purchased my first motorcycle, a 1986 Honda Interceptor 500 with 23,000 miles. It seems to run great except for one problem. When T start it, it waits 1 5-20 seconds and then begins to billow out a pretty substantial amount of smoke. When it warms up. the smoke problem begins to subside, but my friends tell me that it blows out small puffs as I go through the gears under moderate to heavy acceleration.

I know this may be a bit difficult to diagnose with the given information, but I am a college student and I'm trying to avoid my local dealer’s “Gimme 50 bucks and we'll take a look at it’’ advice.

Mike Stewart

San Luis Obispo, California

/ recall a cartoon showing an Indianapolis. Indiana, used-car dealer telling a potential customer that the car they were looking at had "only" 500 miles on it. The car, of course, was an Indy race car. Chances are your "great-running" Interceptor 500 has some serious engine maladies.

A leak-down test will indicate how well the piston rings are sealing. However. even if the oil rings have gone limp, you still may record a reasonable leak-down test result (94 percent or so) and still have smoke. It is also possible that the valve-guide oil seals have failed. Both pist on-ring and valveguide-seal failures are more often due to locally elevated operating temperatures thati high mileage. In other words, if the bike has been run very hard, it may need rings and seals. Unfortunately that is a rather expensive operation for the Interceptor series of motorcycles because the cylinders are an integral part of the crankcase, and installing new rings requires a complete leardown of the engine. 0