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I'm looking to purchase a prop for my boat. Not sure of the the exact size of my currant prop. I know it's a 19p but have to check the diameter. The engine is a 2-stroke 90hp Yamaha on my 1984 17' Montauk. The tach is not presently working so I am not sure of the RPM's at WOT. What type and size prop would be right for my boat? I'm sure there are a few people running the same if not similar set up.

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Hi Harley,

I have similar set up. 90 HP 2 stroke Yamie on a 17 ft. I use a 19 in Black stainless K series prop by Yamaha. I squeeze 5200 RPM out of it with a light load... I also have the same prop in a 17, that jumps to 5700. I will be making some minor changes. Drilling ventilation holes in the prop for better hole shot for water sports. May also add a set back/jack plate. This will allow the engine to be raised an inch or so. May be able to squeeze another 100-200 RPMs with the jack plate.

I have also tried a 19 inch ballistic by Michigan. It was too big. Max RPM was 4900, with light load, 4500 with a load. Not good for pulling. Really designed for bass boats that are very responsive to bow lift.

I am happy with the K series :p