I am curious about your question. I bought a 2004 Lund 1600 Explorer, tiller, with a 50 hp 4 stroke Yamaha (first fishing boat). That is a great boat/motor combination from my limited experience. That model is rated for a 60, while the same boat with a console is rated for a 90. I asked a dealer about weather the difference between a 60 and 50 on my boat would be worth the extra $. He said the difference in performance would not be too significant. I also asked him about putting a larger motor on the model, such as a 75. He said that he would not do that because that would confict with the maximum recommended.
I wonder if a boat with a motor over the max recommended would be in technical violation of your state regs? Likewise, would the larger motor affect the warranty coverage on the boat for transom issues and so forth? Finally, could there be an insurance coverage issue in the event of an accident? What are your thoughts?
By the way, I am used to running camp 17 foot lund outfitters (700+ lbs.) in Canada with 40 Yamahas with 3 people and lots of gear. When we go, its late August and the props are chewed and dinged. Last year they put a governor on the motors because someone had an accident earlier in the season. We were putting around 15-20 mph max. Previously, the 40 moved us pretty well. The 50 on my boat really moves it well with 2 people and gear and full tank. Have yet to try it with 3 people. We will see how it does with 3.
You probably already checked this, but Yamaha has a performance test site for various boat/motor combinations. I found it on google “Yamaha performance” The other responders have more experience than I do. But, for what its worth, I believe you should max out the 1700 with the highest you can within the manufacturer’s rating. Obviously, the 1700 is significantly heavier than a 1600 and it has a larger fuel tank I believe. Good luck.
