An internal combustion engine is provided having {HEAD ~ a pair} of cylinders interconnected by means of {TAIL ~ a narrow connecting channel} 
An internal combustion engine is provided having { HEAD ~ a pair } of cylinders interconnected by means of { TAIL ~ a narrow connecting channel }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL