78 Johnson 115 - NEW Questions

[olseaspirit]

Ok guys, I have read about 100 post on these motors and still havnt been able to answer my questions.

took the boat out to the lake this weekend and it ran good for the first 20 mins or so. Then the motor started acting funny, it would run good at WOT but not idle. it would not rev up very fast even out of gear, and sometimes i would have to choke it before it would start back.

if i got it into gear without it going dead it would plane good and run great at around 5200 RPMs

any ideas of what could be wrong? Just rebuilt both carbs

 

[wavrider]

Re: 78 Johnson 115 Questions

Re: 78 Johnson 115 Questions

There are thermo switches in the heads of the motor,

it should be a brown wire coming out of the cover of your heads, you may have one or maybe one in each head.

It will have a blade connector, just turn your ignition switch on, short the blade connector and you should hear an overheat alarm go off, usually mounted in the control box of the remote.

this is your over heat alarm.

I have the exact same engine as yours, I added a tell tale to mine so I can visually see the water and put two new temp switches in, just to be on the safe side.

Mine also seems to run a little rich at idle, the old v-4 like to drink the gas, it is not so bad on the water moving but in a test barrel stand by for the smell.

I also gap my plugs to .040 to avoid fouling as alot of my time is in no wake zone in the intercoastal.

 

[olseaspirit]

Re: 78 Johnson 115 Questions

Re: 78 Johnson 115 Questions

Thanks, I will try that tonight. How did you put the tell tale in? did you tie directly into one of the two lines going into the cylinder heads? do they sell a kit for this? Thanks

 

[F_R]

Re: 78 Johnson 115 Questions

Re: 78 Johnson 115 Questions

The tell-tale is water droplets blowing out the exhaust relief holes in the backside.

Please don't take it personally, but it is foolish to rely on either the overheat alarm or tell-tale of any kind. Sudden water pump failure will burn up the motor in seconds, long before you ever think think to turn around and look at the tell-tale, or even for the alarm to go off. How do I know? Well how about almost constantly having a motor torn down for new pistons in the shop. The hub would break loose and spin in the impeller and that's it, all she wrote as they used to say. The only half-way safe way to protect yourself is to replace the impeller periodically whether it needs it or not. Fortunatly, the '78 wasn't as bad about that as it's earlier sisters.

 

[olseaspirit]

Re: 78 Johnson 115 Questions

Re: 78 Johnson 115 Questions

I know its foolish, I do replace the water pump yearly simply because if you get an alarm its usually too late.

 

[olseaspirit]

NEW 78 Johnson 115 Questions

NEW 78 Johnson 115 Questions

OK, compression is 117 to 125 across all 4 cylinders, each are firing, just rebuilt carbs.

the boat will run good until it warms up, then it will not idle, runs great at WOT about 5200 rpms, if i adjust the timing so it will idle it will not plane out and has no power

any suggestions? seems like it is running rich

 

[olseaspirit]

Re: 78 Johnson 115 - NEW Questions

any one?

 

[ezeke]

Re: 78 Johnson 115 - NEW Questions

My suggestion would be to take the boat to a dealership that has a test prop and test tank and have them set the timing correctly.

 

[olseaspirit]

Re: 78 Johnson 115 - NEW Questions

My suggestion would be to take the boat to a dealership that has a test prop and test tank and have them set the timing correctly.

haha thats a good answer, if i wanted spend a lot of money on this boat I wouldnt be on here asking for help.
I was hoping for a reply from a mechanic or another owner who had similar problems in the past. Thanks!

 

[ezeke]

Re: 78 Johnson 115 - NEW Questions

I am a 66 year old retiree and a veteran user of the engines.

When I am outclassed, I at least have sense enough to know it and pay for good service .

It is no laughing matter when you screw up a perfectly good motor because you have no idea what you are doing.

If you think you can buy knowledge and skill on the cheap, keep going.

 

[olseaspirit]

Re: 78 Johnson 115 - NEW Questions

I am a 66 year old retiree and a veteran user of the engines.

When I am outclassed, I at least have sense enough to know it and pay for good service .

It is no laughing matter when you screw up a perfectly good motor because you have no idea what you are doing.

If you think you can buy knowledge and skill on the cheap, keep going.

this is the most ridiculous statement I have ever heard
- listing your age as a reply is hillarious
- hinting that I am outclassed and do not have sense enough to realize this
is insulting
- and I will keep going, even if I have to pull power packs/coils/plugs and
even the carbs again if i have to

But in the end I will have a good running motor that i have taken pride in repairing my self , and I will be in a much better mood than you are.
so take your keyboard boasting somewhere else, if you dont have a suggestion then dont reply , everyone on here knows that taking their boat to a mechanic is an option

 

[SKEETR]

Re: NEW 78 Johnson 115 Questions

Re: NEW 78 Johnson 115 Questions

OK, compression is 117 to 125 across all 4 cylinders, each are firing, just rebuilt carbs.

the boat will run good until it warms up, then it will not idle, runs great at WOT about 5200 rpms, if i adjust the timing so it will idle it will not plane out and has no power

any suggestions? seems like it is running rich

Sounds like you are just messing with the timing blind here. I am sure that is what concerned ezeke. Set the timing with a timing light or per Joe Reeves method then diagnose your fuel issue.

 

[olseaspirit]

Re: 78 Johnson 115 - NEW Questions

well after removing the carbs several times i finally found a piece of trash in one of the low speed orfices. cleaned out the carb, syncronized the carbs, and now shes running great. seemed to be getting a little warm though so im replacing the impeller(again)

 

[wavrider]

Re: 78 Johnson 115 - NEW Questions

Check the top of the forum , there are instructions on how to install tell tale.

It is a visual check for water being pumped through the engine.

It does not cover all the possibilities of a cooling problem but it is at least another check for water flow, I guess the engineers think it was a pretty good idea of having as the newer outboards, all models, have them from the factory.

Use Joe Reeves timing method to set timing it works great.

Timing is very important to a two stroke, set it wrong and it can cause big headaches.

this forum is a great place to get info, and the satisfaction of doing it yourself.

good luck.