The Service Department

THE SERVICE DEPARTMENT

GARY BRAY

RELAX?

Recently my friend who has a BMW came over and we decided to take a ride. While riding down Route 17, a four-lane highway in New York State, a gravel truck in front of us was pelting us with gravel. We passed on a gradual curve and just as we straightened up we hit a strip of oil about thirty feet long and six to ten inches across. Almost instantly we hit ground. Due to much scrambling we got out of the truck's way. My friend who was driving was unhurt except for a few scrapes, but I lost a few teeth and had quite a swollen face, despite being well protected by boots, jacket, pants, helmet, etc.

Are there any tips you can give me as to what to do in the future in a situation like this, and also do you think a bubble shield would have saved me?

Jonathan Lewis New City, New York

Although extremely difficult, one should relax as much as possible when control of the machine has been lost. This will minimize injuries. The bubble shield would have stopped the pelting pebbles enough for your friend to have picked a better place to pass, and does give some protection in a spill.

Foreign substances on the roadway do pose a problem in that they are hard to anticipate. Highway intersections, truck crossings, and lengths of road where cars and trucks may be stopped from time to time are the most dangerous places.

From the rider's standpoint, he must exercise good judgment when such a situation arises. Once the machine has gone down, usually the safest thing to do is hold it down. If the rider fights for control after a certain point, the bike will react quite violently.

The passenger, on the other hand, is in a more difficult position. Since he is not controlling the machine he will not be quite as alert as the rider. As far as what to do after one finds himself in the road minus his vehicle, he can but use his own judgment in relation to other traffic. If possible, lie either on your back or side and get your arms and legs as close to your body as you can.

DISAPPOINTED

I have a Honda 150, purchased 7-7-64. I followed the manufacturer's break-in procedure, to the letter. With 500 miles experience on both the machine and myself, I discovered we were one object instead of two, so by the time 650 miles had passed under our wheels I elected to find out how fast we could go ... a disappointing 57-60 mph. The manual with the machine claims 75 mph. Two Honda garages say that there is nothing wrong with the machine, "it's just that all bikes differ somewhat." I feel that a differential of 20 percent from the manufacturer's stated claim and actual performance is a bit strange to say the least.

57-60 mph is all that can be obtained in 4th gear, in fact on some occasions 57 mph has been gained in 3rd, and then when shifting to 4th, the machine has momentarily held its speed, and then gradually it has fallen off to 55 to 50 mph, and held there without much snap in the machine. Now for the question. What is wrong with the bloody thing?

Stan Faubion Spokane, Washington

The unfortunate fact is that machines of the same brand and model do differ. Some just perform better than others for no apparent reason.

I do feel, however, that you can help the speed of your 150 by replacing your present countershaft and rear wheel sprockets. The counter sprocket should be 14 teeth; the rear wheel sprocket should be 40 teeth. A change similar to this has also been found necessary with the Honda 300 Dream.

RE-JETTING

In the September, 1964 issue, Gary Bray stated in the Service Dept. that the installation of megaphones on a 305cc Honda Super Hawk (or any other motorcycle) might require a change in carburetor jetting, and that the engine could suffer if rejetting was neglected. Now, 1 did a bit of research on carburetion and the operation in general of motorcycle engines to try and find out about this, and, at the risk of sounding rather stupid, 1 don't see how the installation of megaphones could have any effect on carburetion at all, much less necessitate re-jetting.

This summer I plan to trade in my old bike and buy a new Super Hawk; 1 also plan to install megaphones on it. Therefore, 1 would appreciate it very much if you would answer the following questions for me: (1) Will 1 have to change the jetting of my carburetors if 1 install megaphones? If so, should 1 re-jet according to my plug readings? If I do not change the jetting when I install megaphones, will the engine lose power, or will it suffer any mechanical trouble such as carbon buildup, etc.? (2) Should I break the bike in on the standard mufflers and then install the megaphones, or should 1 put the megaphones on when the machine is new and then break it in?

Ron Twisdale Honolulu, Hawaii

Any deviation from a stock exhaust system when back pressure is reduced in hopes of increasing a machine's maximum power output (as is usually the case when megaphones are installed) will require some sort of recarburetion. Use of megaphones generally requires richer carburetor settings throughout the entire power range.

The correct main jet size must always be determined by spark plug readings. This rule applies to any motorcycle engine — stock, standard or what have you, if the machine is to be operated at maximum rpm. Lean jetting will cause piston failure while too rich a jet will keep the machine from performing at its best. Tn the lower rpm ranges, throttle response may become hesitant when megaphones are used. A richer carburetor slide (one with a smaller cutaway) and a higher needle position should overcome this problem. From the standpoint of reliability, no trouble would be encountered by fitting megaphones on the machine when new, since the break-in period must still be covered. It might, however, be interesting to compare the difference in exhaust systems by using the stock mufflers while running-in.

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WHY A CENTER STAND?

I have a 1948 Triumph 500cc and 1 would like to know if it is possible to make a center stand for this low machine. My trouble is the metal seal in the clutch case; not until 1949 did they make rubber seals. Is there any way that 1 can seal this or get a seal?

Wolfgang Mannweiler

Colorado Springs, Colo.

While no reference was made to an oil leak, the mention of a center stand and steel washer in the clutch case seems to indicate that oil loss occurs when the machine is put on its side stand. It would be possible to adapt a late Triumph center stand to this machine by shortening it and fabricating the necessarv mounting brackets. This is, however, going to a great deal of trouble if only to prevent oil leakage.

Oil finding its way outside (in the vicinity of the inner clutch case and transmission mainshaft) can be remedied on earlv Triumphs by replacing the transmission main drive gear bushing with a later type, Triumph Part #T-1370. Use of the later bushing requires replacement of the steel washer located in the inner clutch case behind the clutch assembly. Triumph Part #T-1381.

The difference between early and late main drive gear bushings is that the later bushing extends through the steel washer and into the primary case, preventing transmission oil from seening along the mainshaft and running down the inner clutch case to the ground when the motorcycle is leaned over on its side stand.

Over-filling the gearbox will also cause oil to leak out on the ground. This possibility should be looked into before attempting any major work on the gearbox. Capacity of the transmission is 2/3 pint or 400cc.

OIL INJECTION

I would like to ask a few questions about two-strokes that are lubricated by a separate oil pump arrangement, rather than the usual oil-gasoline mixture. There are several of these machines in use (Allstate/ Puch 250 and the Yamaha "Injector" models), and it seems their popularity is likely to increase.

One question is in regard to the type of oil to be used in these models. Should one continue to use a specific two-stroke oil in these machines, even though the oil is kept separate and never directly mixed with the gasoline, or, because of this, can one use a four-stroke oil just as readily or even advisably? Many of us would benefit from your counsel in this matter, I'm sure. Also, since combustion does not take place amid a mixture of fuel and oil in these models, what can one expect regarding carbon build-up in the cylinder head and exhaust system compared with the regular twostrokes? Similarly, what difference is likely to be experienced in spark plug life? Richard F. Gugel, Jr. Lake Mills, Wise.

(Continued on page 32)

The fact that gas and oil are not mixed prior to filling the fuel tank of a twostroke motorcycle fitted with oil injection does not mean these elements aren't combined at some point before entering the crankcase. Since gas and oil are mixed (only the method is different), benefits derived from using oil designed specifically for the two-stroke would remain. Excessive wear in the two-cycle engine occurs primarily from the presence of varnishes and other matter in gasoline itself. Bearing and crankcase seal life may be shortened if the lubricant being used does not resist the formation of waste deposits left by the fuel. Oils developed for the two-stroke do provide this protection. The oil injection system, besides being a lot less bother, supplies only what oil is needed for proper lubrication. By mechanically metering the amount of oil passing through the engine, less oil finds its way into the combustion chamber and exhaust system. The overall result is longer spark plug life with less chance of fouling, and the necessity of frequent carbon removal in the exhaust ports and mufflers is greatly reduced. Connecting a standard ammeter between the ground side of the battery and point of ground does produce an "in circuit" condition. With the ammeter installed at the hot, or power, side of the battery, a burned meter will certainly be the result if a direct short is allowed. However, merely bridging the hot wire with an ammeter will not create a direct short. Natur-

SOME DISSENSION

Regarding your reply to Harvey Ramsey (page 24, March '65 CW), I hope your readers do not attempt to apply your advice to electrical trouble-shooting in general. The type ammeter normally used offers almost no resistance to electrical flow and is always inserted IN the circuit, not across it. If the battery has a negative ground you will get no reading on the ammeter from the negative batter terminal to ground. If it has a positive ground there will be a puff of smoke as the ammeter goes "pfftt" due to the dead short you have just established through it. On some Har ley s the battery negative terminal did not ground direct to the frame, but went to the ammeter which then grounded at the switch panel. Even on that model, a test ammeter will not operate when connected as you describe. I would suggest that Mr. Ramsey carefully dean all terminals in the electrical system. I have seen numerous cases where a little resistance within the switch could cause the trouble. Evert L. Knight Springfield, Ohio

ally, any attempt to connect the plus and minus battery terminals creates a short, but this was not implied in answer to Mr. Ramsey's inquiry. Bridging the ground wire with an ammeter does work whether the system is negative or positive. I have used this method myself for some 12 years. •