Mercury KE4 speed

[mercuryman]

I recently purchased a KE4 and it appears to have a Wizard 6 hp prop. (MB 2091 )) some one bored it to 9/16 inch . I have another MB 2091 prop and it has the 1/2 inch shaft hole. Well this prop is fast it will do 21 mph on my plywood boat . The correct KE4 K50 prop will only get to 19 mph. This is by boat speedometer. The General Purpose Wizard 6 hp prop is 7 5/8 X 7 and the K50 is 7 5/8 X 8. Why isn’t the K50 faster.

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[sydinnj]

Little less pitch will let it wind up a little faster maybe, maybe the shape of the blades, pitch across the whole blade area, there is a lot of factors that come into play when it comes to props.

[hydrojet]

I run a AJ57 7×8 bronze, pushed my light hydro over 25, by speedometer. Reasons stated above.

[speedlinerbu]

That is one beautiful boat!
Tell us about it.

[mercuryman]

I built the boat from plans on internet designed by William Jackson in early 1950’s. I used 1/4 inch fir plywood. I also ran my KG7 and it got a little unstable when it got to 26 mph on a windy day .

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[westwind]

You would need a tachometer to determine if the motor is getting up to full RPM with both props. Sometimes the labels on the prop are not what they are now, if someone repitched it at some point.

[richardg]

One friend filed the diameter of his K50 prop while taking out chips and found he picked up several MPH. We attributed it to the smaller diameter.

[Author]

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