Force 120

[austinmassey14]

I got a 90 force 120hp that runs down the river decent but it tops out at 33.7mph. My boat is glassport 16.5 foot bass boat I feel like I should be able to go faster. Also the boat has a mercury 18p vengeance prop on it. Any help is much appreciated

 

[racerone]

Perhaps the motor is running on 3 of 4 cylinders.----Test compression and test for strong spark.

 

[jerryjerry05]

Gotta figure out the rpm's at wide open??? No tach??
Get a Tiny Tach about 20$-25$
Your motor should run at 53-5500 RPM's
Post that info and we can help you get the speed.
The speedo working right?
You should be able to run at 40-45 mph.

 

[austinmassey14]

I will get a tach soon. Speedo doesn't work either I'm using gps speed off my garmin fish finder. It does too speed of 33 but will go into higher rpm and doesn't go any faster. I'm rebuilding the carbs and reed valves now. Also got spark and compression already checked.

 

[jerryjerry05]

IF??? the rpm's go up but the speed doesn't increase?? the prop hub might be spun.
Check the forum/web on how to test the hub for slippage.