Toning Down Objectionable Exhausts

” The standard of silence is still totally unsatisfactory,” said the judge’s Report on the A.C.U. 1000 mile trial for standard stock motor cycles. And, we think, the public will agree with him. Not the sporty boy, perhaps, estimable though he is. He likes an engine with a big kick and a healthy bark. We hope, however, that he will soon realise that the latter is not essential .to the former.

The future popularity of the motor cycle and its general adoption as a cheap, safe, comfortable and reliable means of transport, is undoubtedly largely dependent upon the good opinion of the general public. There is no room for question that public opinion is prejudiced when a flock of motor cyclists streak along on machines that cackle like a dozen Lewis guns in full blast.

Noise in connection with the motor cycle should not be spoken of without qualification. There are exhaust notes which greatly offend, and others which are almost as noisy, but practically inoffensive. There comes to mind, in this connection, the characteristic note of a famous two-stroke.

This machine is a very long way from being silent, but its noise is like the drone of an aeroplane, and, except to the very fastidious or nervy hearer, is more agreeable than otherwise. It is the sharp barking type of noise that brings out the policeman’s notebook and rouses the ire of the public. That this noise is not essential to speed has been shown by the performances of certain comparatively quiet racing machines.

Amongst the several noise-reducing devices now claiming a good deal of attention is the ” Carb-jector ” silencer—or to be more strictly accurate, tonaliser made by Bridgehead, Ltd., Bankhey Works, Blackpool. The fact that the Blackpool Police motor cycle patrol have fitted their machines with this silencer, should certainly be evidence of its efficiency. The function of the ” Carb-jector “is to reduce the sound of the exhaust to a healthy and pleasant drone. A motor cycle that glided along with the silence of a Rolls-Royce would, perhaps, be dangerous to be comfortable in the hands of certain riders. But it is unquestionably desirable to extract the aggressiveness from the exhaust bang, and this is the job of the ” Carb-jector.”

What the sporting rider, or the rider of a lightweight sidecar outfit, each of whom wants to use every ounce of power his engine can give, has yet to be convinced about, is that there is a silencer which allows an engine to rev, as fast as with an open exhaust. This is where the ” Carb-jector” claims to shine. In fact its claim is even more ambitious. By hurrying up the clearance of exhaust gasses, it is said that this scientifically-constructed silencer, or exhaust scavenger, actually increases the revs, and multiplies the power output.