repowering 2005 Osprey 175

[flounderbound]

My yamaha 2 stroke 90 hp outboard has bearing issues. My mechanic told me it would cost too much to fix it .I`m thinking of going yami 4 stroke.What is the maximum hp I can use?

[RickK]

I think that the difference in weight between the 2 and 4 stroke is the key.  The 175 is pretty sensitive to weight aft and it throws off the center of gravity and can change whether the boat still self-bails or not. Find out the weight of the existing and then the weight of a new 4stroke to see how much more weight you're putting on the aft of the boat. Long explanation aside, I'd look for a 90 to compare.
Also, there is another option on your existing, you can purchase a rebuilt powerhead. I did that on my Envinrude/Johnson. I brought the bad powerhead to them as a "core" and made sure I had removed all the stuff from it that would be needed on the rebuilt one. I'm not a mechanic but was able to swap them.

[flounderbound]

I was told the maximum 4 stroke yamaha motor I can use is a 70 hp.What is the top speed I can achive with a 70 hp 4 stroke motor?I know the weight on the boat (fuel,etc)will affect the speed also

[RickK]

I would guess less than 30mph. Most of the time, with my 90 I am cruising 28 - 30 with some extra in case. If you're ok with the under 30, buy the 70 4S. If your happer with the speed you had with your 90 - go with a rebuilt power head. You don't have to have your mechanic rebuild it, buy one that is already rebuilt. You might be able to get your mechanic to install the power head but of course he won't stand behind anything.

[flounderbound]

I was looking on Facebook Marketplace and saw a 1977 Aquasport 175 with a Yamaha 115 4 stroke outboard on it .How is that possible. I was told I can only put a 70hp 4 stroke on my 175 because of the weight

[BradC]

Maybe that’s why it’s on marketplace … owner’s tired of wet feet …

[BMAC1988]

I would say a 70 would be severely underpowered for a 175 and not be worth the hassle to swap. Not so much even for top speed but time on plane would be brutal if you had any load at all on board.

As for weight the Suzuki DF140 on my 175 is well over 400lbs and I have it installed on a CMC jack plate. The scuppers are for sure in the water at rest and it will hold water in the back recess between the side bins. The performance increase over the Evinrude 88 is nothing more than astonishing as the 88 would even struggle to get on plane when loaded heavy. Top speed with the 140 is 43ish and with the jack plate I could use some more prop so I don't see 45mph being out of the question at all and that is with the t-top. As an additional benefit I can get 5-6MPG with the Zuki over the Evinrude's 3-4MPG