
I just Harvested this Tohatsu 70hp and it is already mounted to my

Of course, that's only when you have the throttle wide open, which on these boats would be less than 10% of the engine's operating hours.Ormonddude wrote:Understand for the engine to hit the Higher Peak horsepower EVERY stroke has to be tuned to the blocks Max Capability.
Not from my understanding of engines lets use my 100hp - 150hp example at 1/4 throttle the 100 is putting out approx. 25hp the 150 is putting out 37.5hp on the same crank and block realize both Engines have the same RPM rating basically the 150 is IMHO is going to break first. I know its open to debate and there is weight consideration. This is just my thoughts on it. I never like the Max HP configuration.Of course, that's only when you have the throttle wide open, which on these boats would be less than 10% of the engine's operating hours.
Herschel wrote:Two questions: 1. The dealers with whom I have been speaking have been assuring me that they will go out on the water and get the right prop for the engine and the boat after the sale and install. Does Bass Pro offer that service, too? 2. I don't hear much about Yamaha on this board, but I have several folks bending my ear that way. I am getting the picture that the Mercury Bigfoot is gong to run about $1,000-1,500 less than a Yamaha. Did that figure into your decision to go with the Merc?I just repowred my 97 MacX with a 50 Bigfoot.
Out the door cost me $6500 with controls and cables from Bass Pro.( 50 bigfoot $5300)
Ditto all of this, especially lack of use. The core issue with lack of use is that engine oils seep to the bottom of everything slowly over time. When you fire up an engine daily, there's oil everywhere, but when you light them up once a year, those first few cycles until the cylinders are well lubricated is equal to hundreds of routine starts. That's why you "fog" an engine with oil when you're going to leave it over the winter.raycarlson wrote:No one would be able to convince you otherwise,but the last thing on the long list of what causes a moderen outboard to have a catastophic failure would be running the higher rated block WOT.these motors are so over built and under rated at 6000rpm there just starting to breathe.It really should not even be a consideration.I would worry much more about cooling system maintence.fuel injection problems,fuel quality,etc.. More outboards die from lack of use then anything else.
eddy wrote:I have a 9.9 yamaha on my x, and was thinking to move up to a 25 or 30 HP. I was planning to travel on a river with some current and assumed that some hp would compensate the current. I don't need to go fast.
Think i stick to my 9.9 then.
That was possibly the best summary of the subject I've seen.JohnCFI wrote:That is really interesting info, thank you.
I would think a 9.9 would be enough for normal running, but if facing a strong wind, a 15 hp would probably make more sense for a boat that size, but I would defer to anyone who's actually used such a small motor on anJohnCFI wrote:So, effectivley, if all I am interested in is the 0-7 knots, with a little in reserve, what HP should I be looking at for good economy.
What is the motor speed at WOT? It's possible you're overpropped, and lugging the engine at higher speeds. Or there are clogged passages. Or the impeller has lost a lobe or three. Or the thermostat is stuck in a partially open position. Lots of possibilities, but you need to start with the engine being propped correctly for the boat.JohnCFI wrote:To sneak in another question, if I run at 3000-3500 RPM or more I get an overheat buzzer after a while, slow down to less that 2750 and it goes away, and will run happily all day. Any suggestions as to cause, someone locally suggested wrong oil type (Tohatsu 50HP don't know exactly but probably only a couple hundred hours up).