Posts: 3508
Location: Elk River, Minnesota | Hiya,
I would bet that there will be a significant decrease in performance by going to the 70hp yamaha. Engine displacement is less in the 70hp along with the added weight... SWorrall is right on that a pitch change downward will be needed and both top end and low end performance will suffer greatly.
I would also agree with fly here...if you can go to more hp (or at a minimum more displacement) I think you would be much happier.
no doubt that the 2 stroke engine has a much better power to weight ratio than the comparable 4 stroke, but things keep improving... but as fly did, he maxed out his hp and loves his rig. I just went through a 2 stroke repower on mine, went from 69 cid in my former yamaha to 104 cid in the equivalent hp johnson... HUGE difference, even though I added close to 100 pounds of weight. 2 stroke to 4 would need even more displacement to get the same performance...
Steve |
