To the disgust of both, when a test was made with the launch still held immovable, and the heating was overcome, explosions in the muffler developed.
“Now we must find whether that is caused by a cylinder missing fire and pumping the gas into the muffler.”
“How will that do it?” asked Chester, who, while a good motor boat pilot, possessed less practical knowledge than his chum.
“The charges which I spoke of are ignited from the heat of the next exhausted charge. It may be the exhaust valve is stuck or does not seat properly, or the gas mixture is too weak to fire in the cylinder, or the spark may be insufficient or over-retarded. It is a job to get that straightened out, and when that is done, perhaps something else will turn up, but we may as well tackle it at once.”
It was fully dark before the difficulty was remedied by a careful readjustment of the carburettor. Repeated tests were made, and everything found to be right.
“At last!” said Alvin, with a sigh of relief. “And now we are ready to go home. But where is Mike?”