got some questions

[Dustin Dockery]

so im new here didnt see a section for introductions but im Dustin and a ag mech

my dad recently bought a boat and we took it out yesterday for some fun and well it was slow to get up to speed and he has to rev it high before he can take off or it'll die..

its a 1978 115hp 115ml78 johnson motor and its on a 16ft larson we want to be able to pull a skier or kneeboard behind it but it dont have any get up and go we have about 600lbs of weight on it. neither of us are really boat mechs but i bought a service manual for it waiting on that but was hoping you guys would be able to offer some suggestions we changed the prop cause the one that was on it was damaged and it was 13 1/4 by 17 what we put on it we have no idea my dad had it laying around from when he had a boat before and it was a spare prop

 

[SEAHORSEJOHNSON]

you changed the prop before finding out it would not pull a skier? or after you found out?

 

[Dustin Dockery]

the prop that was on it was pretty beat up with a couple good size chunks out of it. so we didnt really want to chance it..

ill tell him he needs to change the plugs and check the water pump ill try the spark gauge and ill let you guys know.