85hp suzuki 20mph tops

I am helping my uncle out with his boat and the boat does 20mph tops and does not go any faster<br />it is a 1988 suzuki 85hp. Can anyone tell me what to check for that would cause this. Thanks for you help.

Re: 85hp suzuki 20mph tops

Howdy, 90HP.<br /><br />We would need a lot more info to be able to help you.<br /><br />Go to www.outboardrepairs and look up power loss.<br /><br />If the advice there doesn't help, come back here, tell us what you did and what happened.<br /><br />Good luck.

Re: 85hp suzuki 20mph tops

90,<br /><br />You're probably running on two of the three cylinders. Those engines frequently popped head gaskets.

Re: 85hp suzuki 20mph tops

1988 suzuki 85hp with oil injection. Checked the spark and it was fine and did a compression check and 150lb all round. when I took the boat out I messed with the tilt and trim<br />and the boat ran fine. Can anyone explaine the tilt and trime for me and how that would make the boat go 20 mph until found the right spotanf the tilt and trim.

Re: 85hp suzuki 20mph tops

Make sure the tilt is all the way down before you play with the trim.<br /><br />Sounds like your plowing (bow digging in)<br /><br />If you can't get the bow up with the tilt all the way down kick it out a bit then go back to the trim.<br /><br />The more you tilt/trim out the higher the bow should come uo

Re: 85hp suzuki 20mph tops

Are we talking about an 16' runabout or a 28' CC?

Re: 85hp suzuki 20mph tops

15' thunderbolt bass boat

Re: 85hp suzuki 20mph tops

hi rob,i too have a suzuki 85 and am looking for info to remove lower unit. also what is the serial # range of your motor..thanx. drh

Re: 85hp suzuki 20mph tops

I have a 17.5 ft boat with a DT85 and it does about 35-40 mph so I know your boat will go more than 20mph. Did I read you correctly that you were able to get it past 20 by playing with the tilt and trim or were you still stuck at 20.<br /><br />If you trim the motor up (tilt it forward) it will push the stern down and the bow up. At planning speed this gets more of the hull out of the water, less resistance, more speed. Too much and the prop starts sucking air, you cavitate, and the motor speeds up and the boat slows down.<br /><br />If you trim the motor down (tilt it backward) it will push the stern up and the bow down. This is good for rapid planning but it tends to dig the bow into the water and puts a lot of hull in the water, more resistance, less speed, harder steering.<br /><br />Also, the cavitation plate, should be about 1/2 or so below the bottom of the hull. If its more than that it will slow you down. If you get it too high you will haved problems with prop ventilation.<br /><br />Best place to start trim is with the cavitation plate parallel to the boat bottom and fine tune from there.