We have an old 1973 Johnson 65 HP outboard ... (65ESL73R)<br /><br />When we are at idle in neutral I can rev up the motor no problems. When I put it in forward or reverse, the engine runs fine on idle but when I try to go full out I don't achieve a good speed. We cleaned the carbs out properly. The one thing that we don't have is a battery. We are able to start the motor with a boost and then it runs on its own. Is it possible that the engine needs a lot of power when in gear and full out that since the battery isn't plugged it can't get its maximum electricity to power the coils ?<br /><br />What would be the best things to test ?<br /><br />Does it make a difference if our fuel line from the motor to the gas tank is 3/8 and not 5/16 ? That means that theres more fuel going to the motor than if it were the smaller hose ?