Ranger 481v with gt175

[Ranger481v15]

I have a 481v with a gt175(j175stlese) on it. I have a 6in jackplate. 25p shooter prop.
I got this boat last year so it is new to me. I am only getting 55mph at 5400rpms. I have checked everything I k no it to check. Compression is highest is 110 lowest is 95. I have replaced the power pack, and have tried two different timer bases and stators because of no spark on two cylinders. I believe this boat should be moving on better then 55 mph but I’m not 100% sure what it should be doing. Any help would be appreciated.

[BillDSR]

I have a Merc 175 so there might be a difference in gear ratio, not sure. However, with tournament load, half tanks of gas and two onboard, mine ran right at 62.4mph at 5650rpm. That was with a Trophy 4 blade. I also have a 6 inch jackplate installed. Since then, I've had Mark Croxton balance and blueprint the prop, and will have new numbers for you tomorrow. My suggestion would be to double check engine health and prop to pad. You might want to try a Tempest Plus prop. Others with more knowledge will be able to steer you in a better direction.

[jarhead175]

Might post in the correct motor form. Completely possible I am wrong but I was told all cylinders should be within 10% of one another. I Had a 110-112 on 5 and 90 on the 6th right before it let go while we were trying to decarb the motor.

[mdtritn21]

what year motor is it and is it a ficht

[Ranger481v15]

1990 gt175.

[mdtritn21]

It's only supposed to turn 5500 rpm's but I think you have a lot of prop slip with that old shooter prop. Find a known good 24" Raker and try it.