Service
SERVICE
Len Vucc
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.
LETDOWN SHOCKS
I recently installed a pair of Reeder Gaspring shocks on my 1969 Honda 750. Although the installation gave me a few problems, mostly because of unclear instructions, the shocks seem to work fine, and provide a good ride.
While installing the shocks, however, I inadvertently allowed the air to escape, at which point the rear end of the bike settled down with the fender against the rear tire. In this position, the wheel was locked solid by the weight of the bike.
The thought of an air leak while I’m riding at freeway speeds bothers me quite a bit. Is there some way I can prevent such an occurrence, or must I just take my chances?
Gerald S. Mizes Berkeley, Calif.
The situation you describe is potentially extremely dangerous. It can be easily remedied, however, and should be taken care of as soon as possible. The problem is one of too much shock travel; in the fully-compressed position, the eye-to-clevis distance (effective shock length) is inadequate. To increase the compressed length, a spacer must be installed on the shock shaft, between the rubber bump cushion and the top eye. To determine the thickness of this spacer, compress both Reeder and stock Honda shocks, and measure their lengths. The difference between the two measurements will be the proper thickness for the spacer.
To install the spacer on the Reeder shock, the top eye must be removed, followed by the air spring unit. The locknut should then be removed, and the spacer placed on the shock shaft. Reassemble the components in the reverse order, and use a dab of Loctite on the eye threads as insurance against loosening.
Because of the construction of the Reeder shock, a stack of flat washers can be used as a spacer. This method is also possible for other threaded-eye shocks, but will not work on shocks which have the eye permanently mounted to the shaft. If you have a similar clearance problem, and the latter type of shocks, you’ll have to use a set of spacers which can be fitted externally. Called travel limiters, they can be obtained from two sources:
S & W Engineered Products 2617 West Woodland Drive Anaheim, CA 92801
Number 1 Products, Inc.
4931 North Encinita Ave.
Temple City, CA 91780
LEADED VS UNLEADED GAS
I have a 1977 Honda Gold Wing, and do a lot of highway road travel on it. My owner’s manual says to use low-lead gas because low-lead gas is scarce, I asked my dealer which kind I should run. He said to use unleaded, and I have done so. The bike now has 7000 miles on it, and runs great, averaging 46 mpg on trips. I still haven’t tuned it and don’t intend to until it needs it.
Recently, on a 3800 mile trip to Yellowstone, we visited other Honda dealers and in each instance the dealer would tell me I was wrong in using unleaded gas and I should be using regular. One dealer even said I should be using premium. Who is correct?
Paul Fox, Jr.
Richardson, Tex.
A friend of mine owns a Kawasaki KH250; I own a 750 H-2. Both bikes are two-strokes yet my bike’s owner’s manual says never to use unleaded gas and the KH250 owner’s manual says you should use unleaded gas. Why is this? Wouldn’t the performance of the KH250 be better using leaded fuel or would it be damaged?
William J. Hartleib Columbus, Ohio
Lead compounds are added to gasoline primarily to raise its octane rating. A higher octane rating means the gas is less prone to detonation, also called knocking or pinging, a potentially damaging, localized heat condition in the engine’s combustion chamber.
Generally, it is assumed that the higher is the octane rating, the better is the gas. From a strict performance standpoint this is correct. High-performance vehicles, i.e., the 750 H-2, often have high compression ratios and require high-octane leaded gas to avoid detonation and engine damage. Engines with lower compression ratios (the KH and Gold Wing) are less prone to detonation, and will operate satisfactorily on loweroctane leaded or unleaded gasoline.
There are other factors involved, such as combustion chamber design, valve seat materials, ignition advance, and so on. But a general answer as to which gas is necessary might read: Use the grade of gasoline which does not induce detonation.
The Honda Gold Wing will run quite well on virtually any grade of gasoline, so from a detonation-prevention standpoint, they’re all appropriate. But one additional consideration must be taken into account. Low-> lead, to a certain degree, and unleaded, to an even greater degree, reduce the rate at which deposits accumulate inside the engine. This fact makes the use of lowor no-lead gas quite attractive, as the intervals between tune-ups becomes substantially greater. In fact, a tech representative at Honda Motor Corp. recommended the use of unleaded gas in GLIOOOs for this reason, and is substantiated by the good service Mr. Fox’s Wing has rendered.
If your bike runs well (no detonation) on unleaded gas, use it. Use low-lead gas if that’s the lowest octane-grade your bike will tolerate, and premium if you have a hi-per bike which detonates on anything else.
As a final note on gasoline in general, a common misconception is that if a vehicle runs good on regular it will run better on premium. Wrong. All grades of gas have the same per-unit energy. What premium (higher-octane) gas will do is allow you to run high compression and more ignition advance without detonation. It’s the engine’s state of tune—not the grade of gas— which produces the extra (or lack of) power.
TIRE FIX
What is the proper way to repair a small puncture in a tubeless tire?
Daniel Churcho Chicago, 111.
Like a punctured inner tube, a tubeless tire can be patched to repair small leaks. Because of the stiffness of the tire carcass, it’s slightly more of a hassle, but the procedure is essentially the same.
After locating the puncture, make sure there is no additional debris in or around the entrance point. Place the tire on top of a vise or other semi-round surface, puncture side down. Have a friend grasp the tire beads and pull down and out on the sidewalls to expose the inner tire surface at the puncture point. With a stiff wire brush, thoroughly buff the area around the puncture for a diameter of about 2-in. The surface must be uniformly scuffed, andfree from shiny spots. Clean the surface with a patching preparation, or use alcohol or lacquer thinner. Do not use a solvent which leaves a residue, and make sure the surface is completely dry prior to patching.
The tire should be patched with a good quality inner tube patch of a 1-in. (approx.) diameter. The cut-from-a-sheet type patch will work, but much better are the individual round or oval ones with feathered edges. Follow the manufacture’s gluing instructions, and make sure you roll the patch down securely. If applied properly, the patch will last the life of the tire.
We have assumed that the tire is repairable in the first place. If the puncture is severe, and there is evidence of damage to the cords, you ’dprobably be wiser to replace the tire. And about installing an inner tube inside such a damaged tire? Don’t. While this method will ensure a non-leak fix, the tire’s reduced structural integrity makes for a potentially dangerous situation. If a tubeless tire can’t be fixed with a patch, it can’t be fixed—safely, anyway.
HOT KZ750
I own a 1976 Kawasaki KZ750 Twin. After a 7-10-mile hard run on a hot day the bike feels like it’s overheating. In fact, water will sizzle off if splashed on the crankcase. I assume this means the oil temperature is exceeding 212° F, which is, I understand, too hot.
I’ve searched for an oil cooler for my bike, but could not find one. Could you provide me with some information on oil coolers for my KZ.
Raul del Portillo
Archer, Fla.
If water were to be splashed in the area around the cylinder fins, there would indeed be sudden and sizzling evaporation. Most likely, that’s where the steam is coming from and, being normal for an air-cooled engine, is no cause for alarm. This effect will be more noticeable after hard running on a hot day, as the engine’s temperature will be substantially higher.
Since your bike is two years old and still running, we can assume there are no serious lubrication or overheating problems. If on the other hand, the engine now seems to be running hotter than it had under similar conditions in the past, you may have a mechanical problem. If this is the case, have the engine checked by a competent mechanic.
As for oil temperature, which is not necessarily the same as crankcase and cylinder temperature, 212°F is not an unreasonable figure. But rather than the splash-fizzle method, oil temperature should be monitored with a good-quality oil temperature gauge.
As you suggest, an oil cooler would be beneficial in terms of reduced temperature, but adapting such a unit to your bike poses a problem. None of the oil cooler manufacturers offer a kit for the KZ750 at this time, so you’d have to make up your own adapters, and modify the crankcase to allow installation. Unless you’ll be doing some heavyduty touring or racing, the undertaking might be too complicated and expensive to justify the results. Changing oil more frequently might be a better alternative. ©
