TOPIC: 73 Evinrude triumph 65hp will not Idle?

1973 Evinrude Triumph 65 hp three cylinder.
I have rebuilt the carbs twice and they are spotless inside.
The fuel system is all new: fuel pump, fuel lines, fuel tank.
Fresh 50:1 premix.
New ignition coils, plugs, wires.
Compression: 138, 140, 140

Engine will start immediately on choke, and I can run it down to about 1200rpms after the choke is off. Any lower than that and it will stall out.
I checked to make sure all of the throttle plates are closing completely.
The carburetor to ignition advance appear to be set correctly (the measurement for the linkage rod is set to factory specifications).

According to the factory service manual idle should be at 650 rpm.

Any ideas what could be causing this?

Thanks for any help!

Chris

I'm not that familiar with the triples, but the V4's don't like it when you run the idle mix lean, always better to fatten the idle mixture screws up a 1/4 turn at a time until she idles smoothly. May not be applicable here, but couldn't hurt to try?

I believe the high and low orifices are fixed (non adjustable). Is this correct? Mi 73 Evinrude 65 idles rough (almost like it is leaning out, and will stall when idling to the dock. I would love to know what the answer is.

Any other 73 Evinrude 3 cylinder guys out there?

The carburetors have fixed high and low speed jets.
Thanks for the response MarkS.

73Crestliner,

You are correct about the fixed jets.
Does your engine ever stall when shifted into gear?
What speed does yours idle at?

Chris

If cold it stalls going into gear, but OK when warmed up. Mine idles around 850 in neutral, about 650 in gear.

Does the block warm up properly? If the thermostat was missing or stuck open, the block would not warm to operating temp and this can cause poor idle.

Another thing to check is for a bad reed valve. Pull the airbox cover and hold a small mirror or other smooth surface close to the carb opening, if it's spitting fuel back on the mirror there's a problem with reed valve sealing.

Bad crankshaft seals can cause poor idling. Bad upper seal would be apparent, lower seal is harder to diagnose since the powerhead must be removed for inspection.

Just a few things to throw out there, HTH.............ed

For my 1973 65 I have been concerned that it could be a bad reed valve, so I have purchased a set of new ones as they come up (as these are obsolete parts it is hard to find them new).

I will test for blow-back (as described in above response) when I get the time.

Chris - have you checked for blow-back on your motor?

Ed,

The engine does seem to come up to temperature fine.
I have replaced the thermostat and water pump.
I don't have any leakage from the upper crank seal, it is all dry under the flywheel.

I did notice that fuel was dripping out of the carburetors after I got it running with the intake cover removed. The inside of the airbox cover was oily.

I have a feeling you might be right about the reed valves.
I have owned and worked on lots of two stroke dirt bikes and snowmobiles in my time but I have never had reed valves fail on me!

Chris

Hi Chris;

I just found and solved my problem. I put my motor on a timing light to test spark at each cylinder.

Top Cylinder - spark even and consistent.
Middle cylinder - same.
Bottom cylinder - NO flash at all ftom the timing light. I checked twice, still same issue. Pulled plug to see if it was fouled, and it was without any gap at all - cannot figure how this was possible.

I am beginning to think the shop that changed my impeller, changed oil, rebuilt carbs somehow did not gap the plug. Once I gapped it to.30 she came to life (and blew a bunch of smoke for a minute cleaning up the oil in that cylinder.

Now she idles perfectly (950 in neutral and 700 in gear. I cannot make it stall now at all. I imagine my speed will increase next time I put her in to test (only had time to tank test today).

I hope your issue is as easy to solve!

Mine will idle at about 700 rpms, but not well. Just this year I adjusted it up to 1000 in neutral. I was having issues (mostly with the kids driving when I am skiing) stalling when put in gear. At 1000-1100 it isn't an issue.
Is it possible you set those floats a little to high?

I have the floats set to 1/16" as per the factory service manual.
I have ordered up a set of reeds and intake gaskets I will install this weekend.
Hopefully that will set things right.
Chris

When you did the carbs, did you remove the jets from each carb?
Don't ask me how I know, but they are different and can be mixed up.
Tiny little numbers are on them.

Have you checked for even spark on all 3 cylinders? Use timing light on each to see if firing well (I have seen bad NEW coils, etc...).

I just put in a set of NGK 2522 (BUHX) surface-gap plugs to see how they work in the 65 HP motor.

UPDATE ON NGK BUHX 2522 plugs. Took it out on the water today with the new plugs installed. Motor ran WOT at 5400 rpm - with me only she hit 41 mph on my GPS. With Me, My Wife, my 16 year old son, and my 14 year old daugher it ran WOT at 34-35 mph. Really happy with the performance (and the much improved gas mileage (we spent almost 4 hours on one 6 gallon tank that still has some gas in it).

The NGK plugs are wonderful in this engine - she will idle forever without stalling - even when cold. I cannot believe it is the same motor. I totally recommend for the 73 Evinrude / Johnson 65 HP. These plugs are supposed to run a bit hotter than the original Champion surface gap plugs the original manual called for, and safer clearance-wise than the L77JC4 Champions that Evinrude now recommends. Hope this helps you get yours worked out.