95 115 Johnson OB poor performance underload

Hello,

I just wanted to know before I put any more monies into fixing this motor...If this boat should have any problems pulling a 140lbs salmon skier out of the water with two adults (less than 300 lbs ) in the boat? :'(

The motor was fully rebuild about 40hrs ago by Johnson authorized machine shop...I two different marine mechanics look at it...one put it on a dyno...check compression (great)...check carburetion....found nothing wrong with it.d

Second Mechanic, rebuilt the carburetors (cleaned and re-jet), replace the circulation values and adjusted timing….

Currently I using a 14 x17 pitch prop…The best speed I can get out of it is 45mph @ 5600 rpm…. The major problem is the sluggish starts under load…When I’m alone in the boat not pulling anyone it seems to pop out of the water, but when ever I put an extra person (my wife <120lbs) and pulling my son…it has problems getting out of the water…the last mechanic removed the shim because there was to much negative trim….

One suggestion was that I should replace the power pack….could this effect the bottom end performance????

Any help would be appreciated…Thanks you in an advance!

Re: 95 115 Johnson OB poor performance underload

If it is running on all cylinders then your power pack is fine. You may just need some help on the set up and dhadley is the man for that. Could be as simple as trimming the engine as you pull up a skier.

Re: 95 115 Johnson OB poor performance underload

fireman57 said:

If it is running on all cylinders then your power pack is fine. You may just need some help on the set up and dhadley is the man for that. Could be as simple as trimming the engine as you pull up a skier.

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Hey fellow Canadian. I am having the same issues as you with my 94 115. I think it should have way more snap out of the hole as well. Checked plugs and they are consistently black (carboned up I assume). Where do you live in Alberta? I'm up in Edmonton.

Re: 95 115 Johnson OB poor performance underload

Which 115 do you have? They made both the crossflow and looper that year. Post your model number.

Re: 95 115 Johnson OB poor performance underload

how heavy is boat?how about a 15p for watersking?

Re: 95 115 Johnson OB poor performance underload

Tell us more about the boat, length, weight, type etc...

I put a Stingray Hydra-foil on 91 Cajun f/s 17.5' and it made a big difference in how fast skiers came up. You have to make sure that the motor is trimmed all the way down before you hit it to get on plane fastest and then trim it up so the nose doesn't plow. I use a 17 pitch prop on my 90 115 Johnson and get about 45 MPH at 5500 RPM's so yours sounds about right depending on the boat.

Re: 95 115 Johnson OB poor performance underload

I've check the plugs....Nice choclate brown! The boat is a 96 Glastron GS160 (16' Foot Deep V) The motor Model # is J115TLEDA. I can't see the boat being any heavier than a new GX170 (1485 lbs. (674 kg.) w/o Engine)...I'm concerned about over reving the motor if I use a 15p prop...so I haven't tried one...yet! I'm going to try and video tape the performance issue and post a link to it hopefully Wednesday July 26th....

BTW eric I'm in Lloydminster, AB

Re: 95 115 Johnson OB poor performance underload

Your engine is a 1996 crossflow. Your rpm's are close to normal, perhaps just a little low on top end, but certainly it is running properly with the 17 pitch prop. Setup may be the key. How do you have the engine mounted? is the anti-ventilation plate level with the hull bottom? Props can play a major difference, esp, those with the vent holes in them. Many do run two props-one for crusiing and one for skiing.

Re: 95 115 Johnson OB poor performance underload

emdsapmgr said:

Your engine is a 1996 crossflow. Your rpm's are close to normal, perhaps just a little low on top end, but certainly it is running properly with the 17 pitch prop. Setup may be the key. How do you have the engine mounted? is the anti-ventilation plate level with the hull bottom? Props can play a major difference, esp, those with the vent holes in them. Many do run two props-one for crusiing and one for skiing.

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Re: 95 115 Johnson OB poor performance underload

Hi emdsapmgr, I not sure what you mean anti_ventulation plate??? I'll encoding some of the video taken today and posting a link...

Re: 95 115 Johnson OB poor performance underload

The anti-ventilation plate is the flat plate surface cast into the lower unit, just above the prop. Goes the length of the lower unit. Engines are generally mounted on the boat so that this plate is even with the boat bottom (keel,) or even with the water flowing under it at normal speed. If this plate is buried in the water (underwater) when running, it creates a lot of drag, and you get poor performance and economy.

Re: 95 115 Johnson OB poor performance underload

emdsapmgr said:

The anti-ventilation plate is the flat plate surface cast into the lower unit, just above the prop. Goes the length of the lower unit. Engines are generally mounted on the boat so that this plate is even with the boat bottom (keel,) or even with the water flowing under it at normal speed. If this plate is buried in the water (underwater) when running, it creates a lot of drag, and you get poor performance and economy.

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iamcanadian: just sent my boat off to a local mechanic. found out the motor was getting a little hot on the heads, but not enought for the warning horn (some melted wire casings). we also found that the primer bulb was not holding. as a result there wasn't enough fuel in the bowl and the floats dropped a bit. long story short, the motor was running too lean and getting hot. also noticed that the motor seems to be set a little too low so he's going top raise a notch. both might be contributing to the dogging out of the hole. hoping to get the boat back next week. once I test it out, I'll let you know.

Re: 95 115 Johnson OB poor performance underload

Sounds like some good steps. I personally feel that your boat is a bit heavy at 1450 lbs for your motor. Thats why your hole shot is weak while your top end seems fine. The 300 pound payload with a 140 lb slalom skier isn't very much. I bet you find that the hole shot is tough no matter where the passanger sits, but you could try the bow, if it is open. Raising the motor and getting your max fuel will help your hole shot, but I'm thinking it isn't a factor once you're underway with your skiier. He could try starting with on leg out, dragging behind him, his thigh will act as a pontoon, and then slipping his rear foot in after he is up (if he has a rear toe piece, not a rear full boot). In my family, it is four to six hundred in the boat pulling up a 205 to 220 pound skier, so I hear you!

fp

Re: 95 115 Johnson OB poor performance underload

Don't know it the outboard will make that much difference, but my Searay has a 120 hp Mercruiser with a 19 pitch prop and it pulls me at 220 lb out of the water on a slalom with two in the boat.

Re: 95 115 Johnson OB poor performance underload

Sorry Guys, I finally found the weight of my boat to be 1290lbs,,,,

Freddyray21, can you provide details of your boat length, weight etc...just want to compare!

Re: 95 115 Johnson OB poor performance underload

If, after raising the motor and rpm is below 5800, consider having the prop repitched one inch lower. (Generally, even inch pitches are not availabler in new props anyway). Your motor can run all day at 6000 w/o any problem as long as it's not running too lean, then all bets are off at any 5K+ rpm.

Re: 95 115 Johnson OB poor performance underload

Hi Guys,

Talked with one local shop...he indicated that the pilot jets might be too small that could be the issue...Does anyone have an idea which ones should be installed???? What about Jetting? we are roughly 2000 feet about sea level!