1982 Johnson 115 hp J115TLCNB Outboard Motor Propeller

[KLDARMY]

I just purchased a 1982 ebbtide montego with a 1982 Johnson 115 hp J115TLCNB Outboard Motor. I took it out and it runs great. The problem is that I am reaching 6000 rpms. The manual says optimum operating rpms is 5000. The prop is a stainless steel 13 3/8 x 17 prop. My question is should I go to a 19 or a 21. Top speed is now 41mph from gps(speedo only said 37). I don't want to overwork the engine, 6000 seems too high. I don't want to lose speed but if I go up in pitch I should gain speed if I am correct.If I go with the 19 pitch I'm guessing rpms would be about 5600rpms. Would that still be too far from the manuals optimum rpms or should I go with a 21 pitch to bring it down around 5200? The man I bought the boat from had it set up for wake boarding. I may do some tubing or knee boarding but no skiing or wake boarding. Thanks for any help.

 

[steelespike]

Re: 1982 Johnson 115 hp J115TLCNB Outboard Motor Propeller

Your numbers seem reasonable. 17 and 19 are pretty common with the 115 a 19" should put you about 5600.

 

[etracer68]

Re: 1982 Johnson 115 hp J115TLCNB Outboard Motor Propeller

The 5000 rpm in the service manual is the minimum the motor should run. That motor will run to 6000 rpm, but not for long period of time. I would say 5600 rpm is a good number. I would go with the 19p, and use the 17 when you have a heavy load, and or pulling tubers or skiers, and just keep an eye on your tach, the 17 will give better hole shot, but once on plane, keep it about 5500 rpms. I have three props I use, depending on load, and what Im doing with the boat that day. I run a 1987 90hp, and mostly use my 17p SST prop, and run about 5400 rpm@WOT, but I cruise @ 3400/3600rpms. Im not in a hurry anymore in life.

 

[KLDARMY]

Re: 1982 Johnson 115 hp J115TLCNB Outboard Motor Propeller

Thanks for the input. I will buy a 19p stainless.