Technicalities

TECHNICALITIES

GORDON H. JENNINGS

FOR SOME TIME, our Service Department column has been serving to transmit both service tips and general technical information, with the result that it suffers in both respects. Therefore, we have separated these functions. Service Department will henceforth be devoted almost exclusively to the everyday problems encountered in the service, repair and modification of motorcycles. To handle this, we have secured the services of Mr. Gary Bray, a professional mechanic who builds and maintains racing machines.

My own efforts will now be directed toward filling this column, Technicalities, with all the bits and ends of new and/or significant technical information that finds its way to my desk. The column will not be so very different from the previous Service Department, but will of course be more far-ranging in scope as I will not have to use readers' letters as a springboard from which to launch my longwinded discourses. The subject matter will depend in part upon what you ask for; and in part upon whatever items or random thoughts happen to be available.

For a starter, I would like to say a few words about the new Villiers Starmaker engine. This is an all-new racing engine introduced about a year ago with a great fanfare and a promise of great things. The Starmaker is not, at first glance, much different from other Villiers two-stroke, single-cylinder 250cc engines, but it is the first from that company to be designed from the crankcase up as a racing unit.

Unfortunately, events quickly showed that the Starmaker was no match for the old long-stroke "touring" engine fitted with one of the numerous square-barrel conversion kits, such as the one made by Marcelle. The Starmaker will rev more freely (as indeed it should, having a shorter stroke) but simply would not deliver the power. As you can well imagine, this has been more than a little embarrassing for Villiers.

Now, the picture seems to be changing. It would appear that the intriguing progressive-opening dual carburetors (1-1/8" Amal Monoblocs) were the villains, as the Starmakers with revised carburetion have been doing very well of late. To get a better sprèad of power for the scramblers, Villiers is now experimenting with engines fitted with a single 1-3/16" Amal Monobloc. It seems fairly certain that this carburetor is really not big enough, but larger throats are available only in the GP pattern, and the GP instruments are vastly more expensive. In fact, cost appears to be the reason for using the twin Monoblocs in the first place, as a pair of these are far less expensive than a single GP carburetor of equivalent air-flow capacity.

Starmaker engines in road racing have been modified in several ways, but the most startling of these is the fitting of 1-1/2" GP carburetors. The old squarebarrel engines were often equipped with 1-3/8" carburetors for road racing, and we thought that was huge, but the thought of a 1-1/2" carburetor on a 250 is really staggering. Of course, staggering or not, the big-bore instrument works, and Villiers reports an output of 32 bhp at 8000 rpm from the Starmaker in this form, and the engine will run up to 9000 rpm.

In light of these recent developments, it would appear that the Starmaker is going to live up to its theoretical promise, and it will almost surely become the engine for the many amateurs in the racing game. There are more powerful engines, obviously, but the Villiers Starmaker is exceedingly light and simple, and relatively inexpensive to buy and maintain. These things count for a lot to those with limited time and finances.

Speaking of low-cost racing, there are many people in England who think that the present rules for Grand Prix motorcycle racing should be revised. It is suggested that the four-cylinder engines that have made firms like Honda and MV all but unbeatable should be ruled out of existence. Various reasons have been advanced for doing this, but the thought that the English are simply trying to put themselves in a more competitive position is inescapable. If this is indeed the reason, they are indulging themselves in a little wishful thinking. The plain truth is that the enormous resources of, for example, Honda, would quickly produce a "twin" that would also have a fairly considerable power and reliability advantage. Over the course of a full season of racing, the bulk of the victories will always go to the team that has had the most time, money and talent lavished on its equipment. If Britain's motorcycle manufacturers want to win races, they will have to put forth as much effort and employ as much talent as their rivals; a lot of jiggery-pokery with race regulations would bring them neither honor nor victory.

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Perhaps the answer to England's problem is a pooling of resources. Certainly, if all the bike manufacturers and similarly interested parties would pool their resources, the funds and talent necessary for building first-rate racing motorcycles would then exist. An effort of this sort, if as successful as it could be, would reflect great honor on the British motorcycle industry, and in the end that would be of enormous value in their export sales program. England has the best racing riders and the best racing tires in the world; it is a pity that there is no really top-flight British racing motorcycle to complete the picture.

Of course, what we would like to see is a full-fledged American effort in GP motorcycle racing, but there is precious little chance of that happening — for reasons that should require no explanation. This country's only large motorcycle manufacturing firm is something less than interested in International competition.

Amal's Monobloc carburetors are fine instruments, but because the float chamber is cast into the main carburetor body, there have been some problems in mounting them. The company has now overcome this by making right-hand and left-hand versions of the carburetor. In some installations,this will mean that the chamber can now be facing outward within easy reach, instead of tucked around on the "inside" of the bike between the carburetor throat and a frame tube. In dual carburetor installations, it will now be possible to have both float chambers facing outward where the "ticklers" can be reached. •