Letters
LETTERS
FOUR-SPEED REVERSE
As a driver of a Messerschmitt cabin scooter (in addition to riding my Triumph 21) I was interested in your reply to the "backwards running two-stroke" query in your April issue.
It is with regret that one notes your use of the past tense when talking of the 'schmitt. These machines stopped production in about 1964, but there are still a fair number on the roads of Europe. In the U.K., my club, the Messerschmitt Owners Club (London and E. Eastern area) comprises about 70 enthusiasts whilst the larger Messerschmitt Owners Club of Great Britain has about three times this number. In addition, there are many more (possibly some 2-3,000) in use for daily transport by less fanatical owners.
It is a pity you didn't mention the best feature about this type of reverse, which is the ability to use the full four-speed gearbox whilst traveling backwards. It's a brave man, however, who gets into top gear in reverse, as steering becomes distinctly unusual at speeds of "minus 30." The engine must, of course, be allowed to stop spinning before switching to reverse or the results are catastrophic.
Production of engine spares is supposed to be terminating within two years and vehicle spares, available at the moment, will almost certainly become difficult to obtain in the 1970s. However, the real enthusiasts of the club feel that a few 'schmitts will still be giving enjoyment to their owners 20 years from now.
I'm amazed to find CYCLI: WORLD has actually heard of the 'schmitt — I'd rather assumed that none had crossed the Atlantic. However, you'd got all your facts okay except for that past tense!
RICHARD E. BAIL 28, Weston Road Aylesburg, Buchs England
DOUBTER
I grabbed a copy of the May edition of CYCLE WORLD as soon as it became available, and one of the first articles I read was "Vibration Modes of Two and Four Cycle Engines," by P. E. Wikoff. The premise of this article is quite interesting, and I followed it with considerable interest up to the point where the author begins talking about Schroedinger equations, which have to do with the Heisenberg Uncertainty Principle in wave mechanics and nothing whatever to do with motorcycle mechanics. From that point on, the article degenerates into a blatant satire on other technical articles in your magazine.
I conclude then that, while Mr. Wikoff may not have intended to make motorcycle riders look like a bunch of idiots, he may well succeed in doing so. I suffer from visions of cyclists riding down the street at night, risking their lives to study meaningless patterns in their rear-view mirrors. I hope I am greatly understimating my compadres, and I look for great things from Mr. Wikoff in the future, like maybe studying tire conditions by the whistle they make (which can only be done in an absolutely quiet countryside, of course).
(Continued on page 26)
DON THOMPSON
Los Angeles, Calif. We think you are underestimating your compadres—Ed.
INDIAN SIDECAR
I have been reading your magazine for two years and still think it is best. I enjoyed your issue on sidecars very much, and am enclosing some photos of a sidehack I recently completed. It consists of a 1927 Indian frame and tank; engine is rebuilt stock, 1948 vintage. Sidecar is also Indian, 1938. The engine was a tight fit in
tne early frame, but in getting it in, no alterations were necessary. The late model Chief engine pulls the rig quite well, as the early frame is very light, even while pulling the "chair."
It took me approximately two years to complete. It draws some attention as I ride it on the street, and gets many smiles instead of New York "scowls."
I plan to use it to take me to school. I am a 17-year-old senior at Newburgh Free Academy.
ED DOERING Newburgh, N.Y.
NON BELIEVER
You are putting me on.
The article on page 100 and 101 of May, by Mr. Wikoff. I mean, charging down a busy road at night at 50 miles per and peering intently into the rear view mirror to see which way it shakes.
You are putting me on. You are putting me on, aren't you?
WILLIAM L. CASTEEL Somerset, Pa.
MOANER
I write to moan a bit, about your tests of the BMW R-69S. Both tests, run at intervals of about two years, fail to show the true performance capabilities of this machine. You can hardly be blamed, because the bike you tested was too new to perform well, and secondly, it has to be ridden differently than most bikes in order to achieve maximum acceleration. A friend of mine took his stock, 1962 R69-S to the drag strip at Pittsburgh International Dragway this summer just for kicks, and turned 14.36. With a little tuning and a different rear end, they will do much better, but this is not the way they will normally be ridden. I have seen the speedometer of my 69S at over 120, with 7,000 miles on it. Agreed, the speedometer is no doubt inaccurate, but it is not that bad, as I at least was turning 110. You calculate 118 at top revs in top gear, and a 69S with 10,000 miles on it, and in good tune, will come close to top revs in top gear.
(Continued on page 28)
My whole point is that your road tests of this machine show it to be much slower than it actually is. Even if the BMW were slow, it would be one of the best bikes available, but when you consider that it is one of the fastest bikes on the strip or the road, then it is a truly remarkable machine. I would appreciate it very much, if along about next year, you would seek out a well tuned 69S with 10,000 or more miles on it, note the impeccable condition compared to other bikes in that mileage bracket, take it to the strip and wind it up. I think you are in for a hell of a shock.
CHRIS McINTYRE
Pittsburgh, Pa.
SEVEN DOLLAR THOR
I bought an old Thor motorcycle recently. I estimate that it is about 40 years old.
This does not help me in locating parts, however.
Could you help me in finding out how old it is? The serial number on the block is H5249, the one on the head is 1128. Also, I would like to know how much it is worth. Any literature or advice will be greatly appreciated.
Aside from a worn crankshaft, the engine is in good condition and all parts are there except for the seat and taillight. It also needs a tire and tube (not bad, since I paid $7.00 for it).
It's a belt drive and looks something like the 1912 Pope in your March '66 issue, only it has what vaguely looks like crash bars.
BARRY DANISH
147 Penny stone
San Antonio, Texas 78223
Any Thor enthusiasts around? — Ed.
UNBALANCED
The main reason I am writing is to comment on the article, "Engine Balancing," by Dale Herbrandson. I expect you will receive many letters, so I will try to be brief and try to cover most of the errors.
First, the author's viewpoint of his reader's knowledge is a little mysterious. If a reader has enough knowledge of mathematics to follow his derivations, etc., the only reason the reader will read the article is to review his knowledge of balancing or to see if he can follow the author's reasoning. His comment, then, under the paragraph "Applying the Tools," is slightly out of context. If the reader does not have the skills to follow his reasoning, he should have put many more steps in his derivation to help the unskilled reader. The reader who would be helped most, however, is the reader in the gray area between no knowledge and one skilled enough to follow the author's devious path.
In general, however, the work is excellent and is badly needed to bring some of the rider's knowledge up to even a mediocre level.
Please grant me the favor of letting me point out a few errors.
In the diagram on page 65, the angles 6 and B are not well defined. The equation at the bottom of column two defines the angles to an engineer, but does it define the angles to others?
Next, the author should have put down the general expansion of (a + b)n. This expansion may be found in the Chemical Rubber Co. handbook and goes something like this:
(a + b)n := a" + nanlb n(n—1 ) (n—2) _j_ where 3!
a is defined as 1, b is defined as (—X2 sin2 e) and n is defined as Vi or the square root. These are terms under the square root radical. If desired, the factorial expression might be defined.
His expansion of Cos B is correct, but the third term as repeated at the point "e.g." is not correct. The powers should be 4.
(Continued on page 30)
Under "displacement," page 65, third column, his "y" equation is correct. Under "velocity" his V equation is correct, but is not exactly rigorous mathematics. He
should define 0 exactly as <o = , or to
dt
help the reader in the gray area understand better, he could define it as rpm (rate of change of rotation with respect to time). His differentiation of V is correct, but an explanation of where 2 6 comes from might be helpful. Sin 2 6 = [2 sin 0 cos o\ where the expression in bars is the differentiation expression of sin 2 0.
dv
Next A = —— but does not equal dt
w'dy . w2d2y
r • 1 he correct expression is ^2—
or the second derivative of displacement with respect to rotation. His derivation in column three is wrong, but strangely enough, is correct in column three, page 66 under "acceleration" below the middle of the column. The correct derivation is: a = —Reo2(cos e + 1\2 cos 2e).
At the bottom of column two, page 66, the expansion of sin (e +180°) might have been shown, since there appears at first glance no reason to convert this into sin e. See the old faithful Chemical Rubber book for justification of this step. I fear that you will think I am just picking the article apart. There will be many people in this gray area for which more steps would be a big help. I realize you are not a text book, but too large a step just confuses many people. Also, please don't accept any sketches without centerlines. At the bottom of column two, page 67, what are the angles exactly? Certainly not those that would be assumed from looking at the sketch.
Finally, keep up the good work. We need more articles of this kind. The author's justification of rotating and reciprocating rod weights was excellent. Get him to do another.
LEONARD A. KARBER
Las Vegas, Nev.
KARTING FACTS
I was reading through the May, 1967 issue of CYCLE WORLD, when I came across your article concerning Jon Dahlstrom. I agree with everything you say concerning Jon's talent and all, but there was one phrase which prompted me to write this letter. It was "Karting World, the now defunct go-kart magazine." According to the dictionary, defunct means dead, expired, finished. "Karting World" is still very much in existence, being printed by another publishing company.
Since you have had experience with both a kart and a cycle magazine, perhaps you could tell me why there are so many cycle and car magazines being published today, and only two kart magazines now being printed in the U.S. Let's face it; when it comes to out and out racing com-
petition, the only machines which have a definite advantage over the enduro karts are Formula One Grand Prix Cars. The overall track record at several sports car tracks throughout the nation are currently held by enduro karts. Fifty hp out of 250cc, 140 mph on the straights, at a cost of only around $1,000. What more could a person want? Of course, not very many people get killed racing karts. Maybe that's it. The subconscious mind of most racing enthusiasts cries for blood.
So that's all right. Everyone rush on out to the local stock car track or the local drag strip. There's plenty of danger there!
DAN NEUMANN
Urbana, 111.
STILL STUDYING
This letter concerns the article "Vibration Modes" published on page 100 of the May issue of CYCLE WORLD. Since I have a B.S. degree in Engineering Physics and am working on a Ph.D. in astrophysics, besides being a motorcycle enthusiast, I feel that I am qualified to judge Peter E. Wikoff's article.
Briefly, he has taken what he has modestly referred to as the "Wikoff's Principle," tried to apply some of the things he has heard in physics and mathematics classes, and scattered these tidbits throughout some impressive sounding, pseudo scientific, incoherent mumbo-jumbo. These are about the only printable remarks I have, and I do hope you print them in full. Two things impress me most: (1) the ignorance displayed by the writer and (2) the gullibility of the editor that let the article be published. I still think CYCLE WORLD is the most intelligent motorcycle magazine published. In the future, PLEASE be more careful about printing articles that you don't understand.
(Continued on page 32)
RICHARD BRUNDAGE
Columbus, Ohio
SIMPLE DIAGNOSIS
Congratulations to Peter Earl Wikoff for his marvelous article on "Vibration Modes." The article was a tribute to the ingenuity of the motorcycle rider. Upon reading it, I was so inspired that I immediately set out to follow-up on the idea. After an intensive 15 minute research period, I came up with the following procedure for the diagnosis of faults within the motorcycle engine.
The first step is to fill the gas tank to an integral multiple of the engine's displacement. Now, ride the cycle at an even 46 mph down a very smooth road. With the gas cap off, look into the tank and note the pattern of ripples you observe. Poor compression is indicated by weak waves radiating from all sides of the tank. If you see choppy ripples seeming to originate from the rear of the tank, the ignition timing is retarded. If you can see nothing except the bottom of the tank, you're out of gas.
I am sure of these deductions because I have observed each effect on my own cycle. Besides, what else could those little ripples mean? Seriously for a minute, in Ron Gyalog's "Cycle Word," in the May issue, who is the Yamaha GP rider with initials P.R.?
RON WHITE
DeSoto, Mo. We think you are serious about the ripples, but putting us on about Phil Read's initials—Ed.
A AM RR BOOSTER
It seems that the first thing I read in the June issue happened to be a letter written by a Mr. Samuel A. Coombs, Jr., who made a valiant effort to discredit the AAM RR from the standpoint of expense to the entrant. This irked me to the point of writing this letter before I read the magazine any further.
Apparently, Mr. Coombs fails to realize that a great majority of riders who road race in the Northeast are road racers, period. The competitive road race machine represents a far greater investment than the competitive scrambler, and without such groups as the AAMRR, the serious road racer would have very few opportunities to keep his machine from gathering dust, if he were to restrict his riding entirely to the U.S. The northeastern road racer is more fortunate than his counterpart in other locales, as many CMA road races are also open to him. If he were to depend entirely on the AMA, he would be limited to one event per year at Laconia, unless he was able to travel to Daytona
and Greenwood. Even then, where would this leave the owner of such machines as Manxes, desmo Ducatis, or water-cooled Bultacos? These machines are illegal, according to that AMA rule book, which Mr. Coombs claims to have in such abundance.
As CYCLE WORLD points out so well, road racing is an expensive sport. From the expense standpoint, I would like to point out this fact: an AMA membership plus competition license costs slightly more than the AAMRR or CMA equivalent.
At this point, I would like to make it clear that I am not attempting to exonerate the AAMRR; nor, for that matter, am I attempting to discredit the AMA. My sole interest in the sport is road racing, and I participate in as many of the AAMRR and CMA events as I possibly can, and would willingly run AMA events if they ever decide to organize enough road races in the Northeast to justify the cost of a competition license.
As far as the number of events is concerned, I must admit that I can't road race every weekend "from April to November," but if this were the situation, I'm afraid that holding down a job and properly maintaining my machine would approach the impossible.
In closing, I'd like to compliment CYCLE WORLD for the reply to Mr. Coombs; the sole purpose of this letter is to touch on a few points which CW passed over.
WALDO E. BURDICK, JR. Elmira, New York
