Topic: 1975 Evinrude Mate – Antique Outboard Motor Club,Inc

This topic has 14 replies, 6 voices, and was last updated 6 years, 3 months ago by outbdnut2.

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August 25, 2018 at 2:59 am #10966
shane-r13
Participant
Is 105psi to low for a 1975 Evinrude mate? I bought this little bugger in pieces, I’ve assembled and it starts up and goes. It has used gaskets though. Anyways i’m pulling 105psi consistently but it wont idle right down. I can get it to go just a little less than the start position on the throttle lever.

I realize this may actually be a fuel issue. I have soaked and totally cleaned the carb it has a newer plastic float and not a cork one. But i haven’t personally gone and bought a new Carb kit yet. Likely will when its sitting in the winter.

I also find that since this motor wont idle real low it also seems to rev up and down when full throttle. Is this fuel or compression related?

Shane
August 25, 2018 at 3:14 am #81738
cajuncook1
Participant
105 psi is ok. They kind of like 110 to 120psi, but that being said 105 is not bad. Put two ounces of seafoam or Evinrude tuner per tank with the correct fuel mix 50:1. Premix your fuel and oil in a container then add the seafoam or Evinrude/BRP engine tuner. Mix well and then pour it into your motor’s tank. This will decarb your pistons rings from slug and coking that can prevent them from sealing properly. Long periods of low trolling and long periods of setting up can cause coking and limit ring functioning. The Seafoam or Engine Turner will decarbonize or removed the coked up carbon on the ring and powerhead. This may improve compression if compression was limited due coking of the piston rings.

Make sure your motors tank is clean. Fuel is gravity feed to the carburetor, so sluge in the line can affect delivery as well as an in line fuel filter that is partially occluded. Part 2 in the diagram may need to be cleaned or replaced. Sometimes people place a filter in between the shut off valve and the carburetor. Combination of the filter at the shutoff valve and another filter inline can cause additional restriction of fuel.

I know you stated that you clean your carburetor and I believe you. When you are servicing your carburetor there are somethings that people neglect to do.

1st. Did you completely remove and replace the old packing from the low and high speed circuits? Look at diagram part numbers 30. The packing breakdown and becomes worn over time. If you do not have fresh packing, then air can be introduced in the circuit. The packing along with the compression nut item #16 on the low and high speed needle help seal air from entering the circuits and also prevent the needle from wandering (turning during operation) once the motor has been dialed in properly.

You will need to take paper clip or a small flat tip screw driver to carefully remove the old packing. Don’t damage the threads.

2nd. People forget to remove the welsh plug over the low idle circuit. Item number #6 in the diagram. Below that plug is a chamber that has 3 small hole at the bottom that can get gummed up and affect low speeds or idling. A new plug will be needed to reseal it.

3rd. Check the conditions of your low and high speed needles for damage or gouging. Previous owner or mechanics may have damaged the needles when trying to dial in the carburetor. Needle damage can affect your carburetor’s ability to efficiently mix fuel and air mixture and delivery. Damage can also occur to the needle orifices from needles be tightened to hard.

Setting for your carburetor:

Make sure these are your beginning carburetor settings:

These are going to be the initial settings for the carburetor for starting purposes. Your will later fine tune the settings.

Facing the carburetor you will notice (top) slow speed/idle knob and the (bottom) high speed needle and knob

– Top needle is your slow idle needle. You will gently turn in (clockwise) until the needle is gently seated..please don’t force. Once seated, you will turn out (counter clockwise) the slow idle needle 1 1/2 turns. Leave it there for the time being.

– Bottom needle is your high speed needle. You will gently turn in (clockwise) until the needle is gently seated..please don’t force. Once seated, you will turn out (counter clockwise) the slow idle needle 1 turn. Leave it there for the time being.

quote :

(Carburetor Adjustments – Two Adjustable N/Vs)

Initial settings are: Bottom high speed = seat gently (turn needle clockwise), then open 1 turn out(counter clockwise). Top slow speed = seat gently(turn needle clockwise), then open 1-1/2 turns out (counter clockwise.

Once you have adjusted the idle/slow speed needle and the high speed needles, then snug up/ tighten part numbers 16 and 16 with 7/16 open in wrench enough to feel resistance when you turn the needles, but not too much where it makes it very difficult to turn the needles by hand.

Setting the high and low needle valves properly:

NOTE: These settings should be done a large test barrel or on the boat in the water/lake!! It best to do these adjustment on the boat in the lake or on commercial size test tank. (You can damage your motor running it wide open in a small test barrel.)

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn in (clockwise), waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You’ll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out (counter clockwise) the needle valve 1/4 turn. Within that 1/4 turn, you’ll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turn in (clockwise), start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you’ll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn (counter clockwise). Within that 1/4 turn, you’ll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

Watch these videos, they are little long, but it will give you a good idea how to properly clean and evaluate your carburetor. The carburetor in the video does not have high speed needle, but the video with give you a good general idea. Sorry the 1st and 2nd video pertain to a 18hp and 6hp motors, so just scoot along until you get to the carburetor disassembly and cleaning.

Just jump to video 4

OMC fix jet carburetors part 1 of 10 (Motor displayed 1968 Johnson 6hp)

https://www.youtube.com/watch?v=7MmDOaOQyQg

OMC fix jet carburetors part 2 of 10 (Motor displayed 1968 Johnson 6hp)

https://www.youtube.com/watch?v=PuByx8J-EfY

OMC fix jet carburetors part 3 of 10 (Motor displayed 1968 Johnson 6hp)

https://www.youtube.com/watch?v=FpivbGEv0wM

OMC fix jet carburetors part 4 of 10 (Motor displayed 1968 Johnson 6hp)

https://www.youtube.com/watch?v=-aWICvsQZQ8

OMC fix jet carburetors part 5 of 10 (Motor displayed 1968 Johnson 6hp)

https://www.youtube.com/watch?v=JqB6PLqeTI4

OMC fix jet carburetors part 6 of 10 (Motor displayed 1968 Johnson 6hp)

https://www.youtube.com/watch?v=HS5J_AxJrAY

OMC fix jet carburetors part 7 of 10 (Motor displayed 1968 Johnson 6hp)

https://www.youtube.com/watch?v=Iq_2RfWjQ28

OMC fix jet carburetors part 8 of 10 (Motor displayed 1968 Johnson 6hp)

https://www.youtube.com/watch?v=-lXIVBX_UF4

OMC fix jet carburetors part 9 of 10 (Motor displayed 1968 Johnson 6hp)

https://www.youtube.com/watch?v=-nA_4YmNgt8

OMC fix jet carburetors part 10 of 10 (Motor displayed 1968 Johnson 6hp)

https://www.youtube.com/watch?v=94lcU7y2P9Y
August 25, 2018 at 4:46 am #81740
cajuncook1
Participant
Here is a video of a 1972 Johnson 2hp I had about 4yrs ago. I sold it, it was a great runner. Didn’t need it, I had a bunch of 3hp motors with larger gas tanks. The little Johnson 2hp had 118 psi. It ran smooth and idled down well.

https://www.youtube.com/watch?v=dfSbAsRDyPE

Cheers,

Cajuncook1
August 25, 2018 at 5:10 am #81741
reivertom
Participant
US Member
I have the same motor from a few years later, and it runs fine at idle with 105psi. I had to rebuild the carb and clean and reset things under the flywheel, and it runs great. I agree with others on here, it may be a fuel flow problem. You may also get a bump in PSI after you run it a while. I did do the Seafoam treatment also, and it helped with compression.
August 25, 2018 at 9:54 am #81745
billw
Participant
US Member
I’m starting to think that a lot of their in ability to idle may have to do with the lower crank seal. I have finally figured out how to change one but have not put a whole engine back together and tried it yet….115 IS a better compression number, though.

Long live American manufacturing!
August 25, 2018 at 12:38 pm #81752
shane-r13
Participant
Wow tons of information here. Thank you!!!

When I cleaned the carb. I suppose i did it the lazy way. I soaked it in carb cleaner for a few days. Changed the gasket, float and needle and seat, along with the packing in the high and low needles. My kit did not come with the welch plug so therefore I did not change it. I will have to look into changing that since its never likely been done.

I generally run seafoam on the first fishing trip of the year in all my motors. This year I did not in this motor as I put new rings into in the winter and have only used it once for a trolling motor this year. The rest has been playing with it in a barrel.

Fuel flow from the tank to the carb is good. its pours out when fuel line is disconnected from the carb. I also cleaned the shutoff valve and the tank it self when cleaning the carb. The tank is plastic on this model just an FYI.

As for the crank seal. That is always possible. This motors crank seal came off another parts motor I had so its not new by any means. But it "looked" ok, which generally doesn’t mean much haha.

So in short, I think I’ll buy another carb kit with the welch plug, new head gasket (since the one i have is who knows how old – cant hurt to replace), double check the fuel from tank to carb, and look into a crank seal. They are not to hard to change but it takes a bit of time. Hopefully doing one of those helps. Oh and then I’ll have to adjust the needles again but thats easy.

Another thing to add to the winters projects list!

Thanks for the wealth of knowledge and the links!
Shane
August 25, 2018 at 1:52 pm #81755
cajuncook1
Participant
Ah, a couple things that you brought up that can effect running.

You re-ringed the piston. Please use a fuel ratio of 24:1 to properly break in and set those new rings for at least 8 to 10 running hours.

Reusing the old head gasket should not be done. Reusing the old head gasket can set you up for water leaking into the cylinder.

Reusing a parts motor lower crankcase seals on your current motor can set you up for water intrusion in the crankcase and eventually cause servere crankcase damage. Incompetent lower crankcase seal can effect crankcase pressures and cause fuel delivery issues.

Post a video when you get her straightened up. Always a treat on the forum here.

Cheers,

Cajuncook1
August 25, 2018 at 2:06 pm #81757
shane-r13
Participant
All those points are vaild. Never really considered water intrusion. I knew my seals might be great but was thinking air not water.

I’ve been running 40:1 in it. I’ll make a t a bit richer next time I run it.
August 25, 2018 at 2:38 pm #81760
fleetwin
Participant
US Member - 2 Years
Shane
Have you posted about this engine previously, sounds familiar to me…
Did you replace the piston rings? I seem to remember a post about an engine that couldn’t be made to run after replacing the piston rings, so forgive me if I am confusing your current post with an unrelated one…
First, if you did replace the rings, did you get the piston oriented correctly back in the cylinder? The sharp side in the piston dome reflector needs to face the intake parts, which are on the right side of the engine block when viewed with the cylinder head facing you.
These engines run pretty well, until they don’t…..In other words, when they are worn out internally, they tend to be hard starting, idle poorly, and don’t develop full power. Your compression sounds OK, but new rings are only half the story here. Piston skirt fit to the cylinder wall is critical to ensure the correct intake charges are developed and delivered to the combustion chamber. In other words, you could have great compression, but poor crankcase sealing. And yes, the lower seal on these engines is a common issue. When water gets into the lower needle bearing, things go south quickly, this affects the lower seal also creating a crankcase leak. Damage is usually pretty obvious when you remove the lower seal/bearing/housing…But, be careful, sometimes the needles love to fall out of a serviceable lower needle bearing when it is removed. You may have honed the cylinder oversize when you had it apart, did you hone the cylinder? In any event, if you decide to disassemble the powerhead again, it is crucial to measure the cylinder bore and piston skirt carefully.
All that being said, it is important not just to "assume" this engine is worn out internally. You mention that the engine "hunts/lopes in RPM" at high speed as well as low speed, which is an interesting symptom. I have never encountered a worn out 2hp that hunts, usually just is hard starting/poor idle/low on WOT power. Hunting surely sounds like a fuel delivery problem. I know you said the carburetor looked pretty clean inside, maybe there is a problem with the fuel valve on the tank, these get pretty rusted/crapped up, I’m sure you have already replaced the fuel line. These carburetors usually don’t wear out, but can be damaged from lack of use, corrosion/rust. Oftentimes the throttle shafts get stiff and don’t move easily. Forcing a seized throttle shaft can cause further damage by bending the shaft or distorting the butterfly valve. The easiest thing to do would be to just try another carburetor, but I’m sure you don’t have one on hand…I might have one, will look when I get home. I suppose the reeds could be damaged, it is not difficult to pull the intake manifold and have look also. Like others have said, packing nuts that are loose can create an air leak also. An ignition issue is possible, though unlikely. Like I say, these engines usually suffer from lack of use, things getting rusted and jammed. So, a stiff set of ignition points might created a running issue like this, the point cams often get rusted on these engines also, make sure the oiler wick is in place and properly lubricated.
I know you see this as a fun project, and it is for sure. But, it is easy to spend a lot of money on powerhead repairs, so I don’t recommend getting in too deep on this little engine.
August 25, 2018 at 2:44 pm #81761
fleetwin
Participant
US Member - 2 Years
quote Shane.R13:

All those points are vaild. Never really considered water intrusion. I knew my seals might be great but was thinking air not water.

I’ve been running 40:1 in it. I’ll make a t a bit richer next time I run it.

A bad lower seal/housing/needle bearing can draw water into the crankcase. And, like others have said, it is never a good idea to "reuse" old gaskets, especially ones that might create internal water leaks. Have you had the exhaust cover off? A bad gasket, corroded/distorted exhaust cover can certainly create internal water leaks.
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