1985 115 johnson questions looking for answers

[rigamortis]

New user I have a johnson 115 horse with a ballastic 13.5 by 17 and I was wondering what is top end rpm supposed to be is it safe for it to run 7000 rpms its all stock internal also what fuel pressure should I be at I run an holley blue with a fuel pressure regulator also my other question is how do I set the timing need to know where number one is got where to adjust and how to check timing thank you for any help it will diffently help

 

[wilde1j]

Re: 1985 115 johnson questions looking for answers

Prop for ~ 5800 @ WOT ... 7000 is too high. 3 to 4 psig on fuel. See shop manual for timing procedure.

 

[rigamortis]

Re: 1985 115 johnson questions looking for answers

Don't have a shop manual that's why I was tring to see if someone could tell me where number or which ever plug wire you have to be on for the light also will it kill the engine to run over 6000 rpm topend because the motor seems to come to life at 5000 and I thank you for the help just let everyone know the motor is on a 16.5 bass boat and also is it easy to switch to an 6 cylinder powerhead I can still run the same gear case and mid section

 

[tal]

Re: 1985 115 johnson questions looking for answers

Depending on the weight of your boat, it sounds like you need a higher pitched prop. Too much low end will make too many rpms and kill your top end. I'm in the process of putting a 1985 120hp on a 16ft skeeter bass boat. The 120 currently has a 21 pitch prop. It was recommended to me by a local mechanic to up the prop to about a 25 or 26 to help top end since these motors make so much torque.

Again, all depends on the weight of your boat but a 17 pitch prop sounds really extreme to me.

Oh, standing behind the outboard, top right should be your number one.

 

[reeldutch]

Re: 1985 115 johnson questions looking for answers

what is the objective of the engine?

want to race???

 

[rigamortis]

Re: 1985 115 johnson questions looking for answers

Not really race per say we use the boat primarly to ski or tube just for fun but I would eventually like to be able to take this boat to hot boat rallies and run faster don't we all get the itch or is it just me. Also just looking for the info to be able to make it better got it as an old broken down boat and slowly but surely making it better that's all thank you guys for the help

 

[reeldutch]

Re: 1985 115 johnson questions looking for answers

so if you want to keep the motor for a while, dont run it at 7000 rpm.

set it up at 6000 you will be fine when you tow a skier.
hight , load, prop size.

 

[rigamortis]

Re: 1985 115 johnson questions looking for answers

Ok prop is a ballistic 13.5 by 17 and not sure on load or hight what does that mean alittle new to boat termanoligy cars and trucks I would be fine work on them for a living

 

[wilde1j]

Re: 1985 115 johnson questions looking for answers

You need to try a 23 or 21" pitch prop. You'll get more speed and motor will last longer. Six cylinder powerhead not a good idea. If you want more power, sell your motor and buy a bigger one.

 

[rigamortis]

Re: 1985 115 johnson questions looking for answers

I have a four cylinder now if I change to a v6 powerhead that has more base horsepower then i would be better off right and then i can use my midsection and lower unit right and is there a way to change the rev limter in the stock configuration. Because last time in the water it 7000 rpms no problem then changed the set screw under the flywheel which i thought was the timing adjustment and now it runs 5800.

 

[wilde1j]

Re: 1985 115 johnson questions looking for answers

You changed the timing to change the RPM? Wow! You're looking to smoke the engine. Get yourself an OEM shop manual and set the timing correctly. I wouldn't run it again until you do, but, hey, it's your motor.

BTW, rev limiter is in the powerpack and different ones have different limits.

 

[rigamortis]

Re: 1985 115 johnson questions looking for answers

so iguess its the same thing in a gas four stroke that i was basically ripping the tops of the pistons off i agree with no running it till i get it set right. Also if nothing changes but the tirm can i run more rpms than with the motor down like i said in a earlier post im new to boats but very good with the four wheeled brothrin. and im diffently glad to find the forum here and on scream and fly yall all have been helpful

 

[rigamortis]

Re: 1985 115 johnson questions looking for answers

hey by the way i was wondering what the other gentleman was talking about hight load when im pulling a skier what all does that mean or what info was he looking for

 

[emdsapmgr]

Re: 1985 115 johnson questions looking for answers

Also, check your tach for the correct setting. Would be unusual for that engine to run 7000 under load. On a stock engine, the torque and hp drop off significantly over 5500-5700 rpm, so it is best to prop it to max out rpm in that range. Turning it over that rpm range can reduce the long term durability of the engine. I carry two different props and swap them when I want to pull skiers or go fast.

 

[rigamortis]

Re: 1985 115 johnson questions looking for answers

Thank you guys for all the help I diffently going to get a shop manual and set the timing and also the fuel pressure and see how it works and the two prop idea I probably will due that sounds like a good idea