Hi! My main motor is a Johnson 50hp 2 cycle, 1992. Runs great. I have an 18-foot lifeboat. Speed is NOT an issue. My backup is a 1987 2 cycle 15 hp Yamaha. Works perfectly. If I change the fuel connector on the Yamaha and on its tank for Johnson connectors, both my fuel tanks could be used on either motor. Does the small difference in the fuel line diameter make a big difference ? Thanks for your time. Greetings from Northeastern Québec where it is FINALLY cooling off a bit.