Back when I had a 24'Explorer (mid-90's), powered by a Yamaha 250, I also had a kicker for trolling. I used a Yamaha 9.9 4-stroke, and it did fine. Their 9.9's have a lot of torque, and have larger props with a lower pitch, so they work well. I think Yamaha' niche' with that engine might be for sailboats. It pushed my boat up to about 6 knots. And just plumb it right into your main fuel tank (use the aux pickup); no messing with gas/oil mix.