1970 Evinrude 85 HP outboard

[explorer1803]

I purchased a boat two years ago that was used at an altitude level of 2432'. I use this boat at an altitude of 5200'. I have a service manual that advises me on how to adjust the slow speed idle. However, what exactly do I need to do in order to achieve the maximum performance out of this outboard concerning the carburetor at high speed operation.
Thank you!

 

[tashasdaddy]

Re: 1970 Evinrude 85 HP outboard

high speed is a fixed jet. the recommendation now is to prop the motor to 5500 rpms at wot.

 

[explorer1803]

Re: 1970 Evinrude 85 HP outboard

Thank you for your reply. However what does prop the motor to 5500 rpm wot mean. I am not super mechanical about outboards.

Another question. I never need to add oil to my lower unit. However, when I take the boat out of the water, black goo comes out of the propeller exhaust. Is this because the boat is running way to rich either at lower rpm's and also at high rpm's. If so, will this severely damage the motor.

Thank you.

 

[tashasdaddy]

Re: 1970 Evinrude 85 HP outboard

whether of not you need to add oil, it should be changed with new seals on the drain and vent plugs every fall before the first freeze. you need to know your wide open rpms currently, a tach, timing light, etc. then you need to select a propeller that will achieve the proper wot rpms. they come in many different sizes and pitch.
http://forums.iboats.com/showthread.php?t=207285

 

[explorer1803]

Re: 1970 Evinrude 85 HP outboard

whether of not you need to add oil, it should be changed with new seals on the drain and vent plugs every fall before the first freeze. you need to know your wide open rpms currently, a tach, timing light, etc. then you need to select a propeller that will achieve the proper wot rpms. they come in many different sizes and pitch.
http://forums.iboats.com/showthread.php?t=207285

I have been running a 13.25/17 prop on my boat at an elevation of 5200'. I have purchased a 13.50/15 and will try it out in the next week and let you know how it works out.
Also, since I can only adjust my low speed carb jets, what is the best way to do this. Should I warm up the motor. Then turn all four jets all the way in then back them out one turn and got from there.

Thank you and please advise.

 

[explorer1803]

Re: 1970 Evinrude 85 HP outboard

I went from a 17" prop to a 15" prop at an altitude of 5200'. At full RPM I did not notice any increase in speed?? Was this a waste of money on my part?

Also I still have a motor problem. My motor will start up and idle just fine. However, when I try to accelerate the motor cuts out bad but will eventually reach full RPM's then seems to run just fine. I have replaced the plugs, made sure the fuel filter is clean, I have very good gas/oil mixture. I have also looked for any loose wires or burned wires underneath the flywheel but don't see anything wrong. I do not have a flywheel puller so can only visually look at the wiring underneath the flywheel. Could the amplifier be bad? It is only 3 years old and does not have that many hours on it. Also, what about the distributor cap and spark plug wires?

Can someone give me so good sound advice before I take it to a repair shop.
Thank you.

 

[explorer1803]

Re: 1970 Evinrude 85 HP outboard

Can someone please advise me on this.
Thank you.

 

[explorer1803]

Re: 1970 Evinrude 85 HP outboard

I tried everything as mentioned in my earlier threads but could not get my motor to accelerate properly. So I took it to a boat shop. I think they replaced almost every electrical component before they found a dead short in one of the wires on the motor. Needless to say, I wound up paying more for the repair job than I did for the whole boat 21/2 years ago. I am running the boat at an elevation of 5300 feet. I have a 15" prop and also a 17" prop but do not notice any real difference in performance when I change them??? Any suggestions on this. Also, how can I get more performance out of my motor?

 

[jimmbo]

Re: 1970 Evinrude 85 HP outboard

What rpm is the engine reaching at wide open throttle? Without this bit of info it is difficult to determine if you have the right prop.

 

[explorer1803]

Re: 1970 Evinrude 85 HP outboard

The motor is appx 5500 at wot with the 17 inch prop but it takes it awhile to get there. If I put my 15 inch prop back on shouldn't I realize faster acceleration at wot as well as better performance? Again, I am running the boat at an elevation of 5300'.
Thank you and please advise.