first off motor runs strong it is a 1996 Johns spl 112 that is an a 1996 pro master CC compression is good and spark and timing are all good. when i bought my Boat it has a Stainless steal prop on it. when i run it up to WTO the RPM will max out at 5600-5700 the Max on my motor is 5000 per the manufacture recommendations so i never go over 4500 that just me i believe a lot of motor issues come from people over revving there mototers with the wrong props and ever thing just to get 4mps more out of them with me and my son it will run about 37-38mph but when i put a few heave guys the boat struggles to get to plain cold I have the wrong prop on here what is the recommend pich for a stainless steal prop on the motor my grand father and dad had this same motor and never had a issue ever with theres the only think i had to do was replace a starter and i need to change the fuel lines soon but right now my issue is it seems to struggle with i have a bit of weight in it. or if i am coming in to a head wind it seem t lack power to pop it up on a plan with a lot 4 men in it or a strong 25mph head wind can someone tell me what prop i need for this motor and the pith i was thinking a 20-21 i dont mined give in a few mph for a better boat that does not run over 5000 rpms

What is the length and weight of the boat?

Everything I can find online says your max RPM should be 5500. Where did you get max 5000. I think with the extra weight it just too much to get your boat on plane. Sounds like its working like it should. If in Waco I have a SE Sport 300 hydrofoil that I am not using, it may help you get on plane. Its Free to you. Hope this Helps.

what prop do you have on it now?

Are you trimming down to get up and moving?

I may take that foil can you pm me i will be up that way this weekend thanks can you send me your phone number if you cant fish i can offer you some bait . i could really use it if it will fish my 112ph

to take you cat fishing a few times. t i cracked mine last time i was out at granger
that 5000 max in on the conceal and the motor my grand father said the samy it should be 5500 someone my have put that one there to keep someone from over running the motor
but ir runs the best at 47-4800 it will do close to 40 but runs the smoothest at 32-35mph i dont need to go fast i just want to get there i have kids and crippled guys in my boat all the time. I sent stave an pm but never got back to me. the pitch is 17 x13 1/2 i was told today by the shop the motor is set way to high when i am running on a place you can see the fin the lower end is barely in the water. I was told to lower the motor on the transom the boat is a 1996 pro master 18.5

the motor has 3 holes for mounting it and mine is set as high as it can go i was told to lower it as low as it will go and it should take care of it

the extrea weight should not be an issue i have been around this motor for many years and they have alway been very strong and can push 5 guys on my grandfaterhs boat just fine i really think it is like the shop said the motor is set to high the guy who had it before me use to run it in skinny water so i am sure he did it and never put it back down

That is interesting, that is the same size blade I run on my 85hp Evinrude.

A 17P, 4 blade is optimal for that HP. You want it to run at max rpms at WOT, so when you have it loaded down it doesn't struggle as you say. A higher pitched prop will just make holeshot worse.

that is what the guy at Killeen Boat world said. it has the right prop and going up with jut make it work then i took the boat down there the notice the motor what set on the bottom bold hols lifting the noter about 3-4 inches between the transom and the mount of the motor. he said some one raised t to probably run it in shallow water and never put it back it was affecting the plain. the problem is the silicone the mount and i tried to move it but i twisted my back and my sone had to pretty much cary me in the house. having a jacked up hack is hell when you need to do something you cant. when i finly get it on a play with will cruse at close to 40 with a boat load oo people with just me it will do over 40 if anyone is in the killeen copperas cove away and could give me a hand i can pay a little money just to lower it to the top bold holds

Lewis if you are going to pull your motor you need to clean your steering cable and tube.

My dealer told me that the cavitation plate on the motor should be about water level when running at cruising speed. Mine was initially low so I raised it an inch. it was easy to do the Steve's jackplate but after doing that, I seemed to get a lot of what sounded like a combination of exhaust and cavitation noise so I lowered it back down where it was and the noise went away. I didn't notice a difference in performance at all, but then I'm not trying to get 70MPH out of a bass boat.
The important thing is to get the motor to run at the max rated RPM with the boat loaded like it normally is. Then you can get the prop worked if you need to, but with a utility fishing boat, that probably isn't going to be worth the $$$ to try to tweak it.

Good advice on checking that cav plate location while running. We replaced a Yamaha 90 with a 115 Johnson and the dealer set the motor too low. Holeshot is fine but when you start to trim up the cav plate "digs". Get her on plane and have yourself or someone else look over the stern while someone is driving to see how high the cav plate is out of the water. You should be able to trim up without the plate digging in the water. A cheap and easy solution would be to get a rapidjack from Steve and adjust as needed till you find the sweet spot. But I believe that promaster has a plywood transom so you may want to have a shop check its integrity before you add a plate.