Have an older Nissan 5hp which has an internal tank. I have to fill it often and am looking to purchase another motor. The 5hp does not seem to move the boat forward very fast so I am thinking about purchasing a larger motor. I hate having to mix my oil and gas so I am leaning towards purchasing a four stroke. I have had a 9.9 two stroke on an older 22 footer in the past. Is a 9.9 to large for the Capri 18