The Service Department
THE SERVICE DEPARTMENT
GARY BRAY
IT EATS PISTONS
I have an Allstate (Puch) 175 which is a very dependable machine except that I ride about 2,000 miles a month and keep burning holes in the rear side of the front piston. I have been replacing the piston about every 5,000 miles. Since there is no dealer around except Sears, I have to do all my own servicing.
The bike is stock. 1 have been running Esso Plus gas and SAE 50 Valvoline oil, 24 to 1. Pistons have been rather gummy, so I switched to SAE 30 Texaco outboard oil, 20 to 1, about a week ago and the pistons look cleaner already. Timing is right on the button, condenser is good, spark plug is Champion L-10, cooling fins are kept clean. Most of my riding is on the highway but I have been holding it to 50 or 55 lately and it still eats pistons. What do I do now?
Tom Wade Burlington, N.C.
The change to an outboard oil was a good move, but I think the problem you have experienced is due to the heat range of your spark plug. For hard cruising I would recommend Champion N5 or N3, NGK B6 or B7, KLG F-80 or Lodge 3 HLN. The electrodes should be light brown after a quick test run.
The conditions under which you use your machine may warrant a change in carburetion. If after changing to a colder plug there is still an indication of excessive heat, I would raise the needle and increase the main jet one size.
WHAT HANDLES BEST?
Is there a motorcycle frame that is more suited for broadsliding on dirt than any others? If so, is there one that will hold a 1964 Triumph Bonneville engine? Also can you get roller-bearing connecting rods for the 1964 Bonneville? Would it be advisable to put these type rods in a Triumph that is to be used for TT racing? Also what size A mal carbs would you recommend?
Sam Hinze Stuttgart, Arkansas
A rigid frame such as the BSA dirt track chassis would be more suitable for pure broadsliding. However Class C competition rules do not permit such combinations of engine and frame.
The 650 Triumph has been extremely successful in TT racing. Handling characteristics of the late Triumph frame are very good. For competition, the front forks do require stiffer springs and double action dampeners. These components should be available through your Triumph dealer. Roller bearing connecting rods are not available for Triumph. The standard 1 3/16" Monobloc carburetors are quite sufficient for all around performance.
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IS IT SAFE?
Please give me your opinion as to whether safety is being sacrificed in riding a cycle that does not track. The rear tire tracks about one-half a tire width to the right of the front tire plant. (Run in moist dirt and on pavement after run through shallow water.)
The machine is a 250 Honda and used mostly for street driving. The machine feels and drives ok. My dealer tells me many machines are driven that way and it will cost around $25.00 to have the frame straightened. Is it worth it?
Robert J. Ahrens Los Angeles, California
A bent frame or associated components such as front forks and rear swinging arm assembly do under most circumstances create an unstable condition. This is largely determined by what’s bent and how badly. Excessive wear to tires, rear chain and final drive sprockets can also result from damage to the chassis. Sometimes the rear wheel is in poor alignment. This gives the impression of a bent frame.
By sighting down the rear chain and seeing that it runs true in relation to the final drive sprockets, correct rear wheel alignment can be determined. Assuming the machine has been looked at and a bent frame is evident, I would have the necessary work done to correct the trouble. Any ill effects to handling may not show except under high speed and/or poor road conditions. Then it may be too late.
A POWER LOSS
/ have a 1955 BMW R25/3 which 1 recently had overhauled. After running it for a short time it began to heat up and lose power. I had the timing set, but that didn’t solve the problem. What do you think is wrong, and how can 1 fix it?
George Briedis Manlius, New York
First off, the valve clearance should be checked. The correct settings are .006 for intake and .008 for exhaust. This should be done with the engine cold. If for any reason the valve clearance has taken up you will experience the symptoms you describe.
Since the machine was recently apart, the camshaft has in all probability been disturbed. To check cam timing, put the machine in high gear. With the spark plug removed, rotate the rear wheel forward until both exhaust and inlet valve are slightly open. At this point the letter “T” should be visible through the inspection hole in the crankcase. This mark on the flywheel indicates that the piston is at top dead center. By rocking the rear wheel back and forth at this point you can determine if both valves appear to be open the same amount. This is known as splitting valve overlap. If one valve appears to be open more than the other, camshaft timing is incorrect.
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Should this seem to be the difficulty, I would suggest you see your local BMW dealer or whoever did the work previously. For the inexperienced, cam timing can be confusing and some special tools are required.
CONDENSATION
Can you tell me if there have been any problems with the unit engines and transmissions of condensation forming in the primary drive case?
Harold W. Fry Redondo Beach, California
No more than any other transmission or primary drive. Condensation occurs most frequently when a machine is used for short periods of time and never quite warms up. The appearance of condensation can also be traced to frequent washing of the machine. Simplest method of dealing with this problem is a good long ride, followed by an oil change.
WILL IT?
ƒ am new to motorcycling and I have two questions to ask you. First, do you think a Honda 250cc could make a 400 mile trip with no stops except gas and meals without harming the engine? Second, what exactly is an engine seizure, what causes it, and is it just racing machines that have them?
Dan Blackburn Ypsilanti, Michigan
The modern 250 is quite capable of making such a trip. In fact if reasonable cruising speeds are maintained (50 to 60 mph) coast to coast travel is completely feasible.
The term “engine seizure” refers to one of several problems. Most common of these is piston seizure. This can be caused by insufficient piston-to-cylinder wall clearance, too hot a spark plug, carburetor mixture too lean, failure in the lubrication system, and incorrect machining of the piston itself.
Other causes of engine seizure can include: connecting rod failure, broken main bearing and even a broken camshaft. In rare cases what appears to be a seized engine is traced to a malfunction in the primary drive or transmission. These problems can occur in any motorcycle, not just racing machines.
MICKEY MOUSE?
What is an energy transfer ignition system and how does it work? 1 once asked a fellow who works for a BSA dealer and all he could tell me was that it’s “mickey mouse.”
Pete Hansen Santa Clara, Calif.
In simple terms, an energy transfer system is an A.C. generator with, shall we say, added incentive and a more definite direction (we hope). As an example: Two of the six coils normally used for keeping the battery charged are wired in series and connected to the low tension side of an external ignition coil. A set of points bridges this circuit and they are closed much longer than a normal magneto or battery coil ignition system. This allows the current to flow mainly through low resistance points and very little current goes through the coil.
At the appropriate moment (again we hope) the points open and current which has built up in the generator coils is diverted through the secondary coil winding to provide ignition. The biggest problem encountered with this system is timing the points to open when peak voltage has been obtained from the alternating primary current. In some cases the magnetic field, or rotor as it is called, may be positioned incorrectly on the crankshaft. When this occurs one may find himself timing the engine to the ignition rather than vice versa. I might add that this causes much confusion.
In comparing the energy transfer system with a conventional magneto, it must be noted that the energy transfer system has fewer moving parts to cause trouble. ©
