50 hp evinrude triple low speed issues and short top end

[ShoestringMariner]

Hey guys, tried out my new to me 50 and it did not run well.
Fires right up, no issues
Warms up well on fast idle.

Slow acceleration is issue one. It does a fast ch-ch-ch stutter until I give it more throttle and then it clears up and then it runs nicely. Electrical??

It has no real top end. It feels like there should be more revs but there’s not. Prop size issue? Tune up issue?

Back at the dock, it won’t stay running at an idle while I wait for the other boats to clear so I have to do fast idle circles to keep it going.

The compression on this motor isn’t wonderful 105-110 ish, so should be ok. No?

What do you guys think? Carb rebuild?
What about the stutter? That feels like ignition.

Edit: no tach, harness coming. Mid July

 

[jimmbo]

Engine needs 3 three things to run;
Compression in both Crankcase and Cylinder
A Strong(strong enough to jump a 3/8" Gap) Spark, delivered at the Proper time
Fuel supplied in the correct portions

Take any of the above out of the Equation, and the engine doesn't run, or doesn't run well

 

[ShoestringMariner]

Agreed, but to clarify;
Compression in the crankcase to run pump and move fu to cyl? What would the suspect cause be here? Gaskets? Reeds?

Do you think 105-110 is getting low enough to cause idle issues? I’d think 85-90 to be consider low, right? Im thinking that’s more carb issuers and low speed circuits. Motor sat on a stand in my garage for 2 years…

I’ll check the spark gap. Wish I had a remote cranking button. Any cheap ideas I can rig up at the motor? Does the spark normally get stronger as the rpm’s increase?


And thanks

 

[jimmbo]

A couple of pieces of wire, long enough to be a few feet away from the engine, so fuel vapours and any spark from the wires, don't come into contact, with clamps on one end, and bare wire on the other end. Attach one to the Battery Cable where it is attaches to the Solenoid. The other wire goes on the Terminal(on the Solenoid) that goes to the Key Switch. Touch the two bare ends together to crank the engine.

Low Crankcase Compression can be from, but not limited to, Leaky Crankcase Gaskets, Leaky Crank Shaft Seals, Broken or Damaged Reeds, Scored Cylinders, Weak/Broken Piston Rings.

Is the Ignition producing a Spark that can jump a 3/8" Gap, on every cylinder?
Are all carbs getting Gas?
Are all the Circuits in each Carb Clean?
Are the Floats Buoyant/ and properly adjusted?
Are the Mixture Needles(if there are any) set correctly?
Are the Carbs all in Sync(fully closed at Idle) with each other?
Are the Carbs properly Synced to the Spark Advance?

 

[ShoestringMariner]

Great thanks Jimmbo. Appreciate the crank wire idea. I thought it would be more elaborate than that, so no complaints here!

I’m definitely going to clean/rebuild carbs and I’ve done the link & sync before. I’ll blow out or replace smaller fuel lines. (Probably the latter)

I’ll check the spark gap too.

 

[jimmbo]

Harbour Freight probably has some Remote Triggers for very little money. With the Bare Wire, be very careful not to get too close the motor, cause if it sparks and there are Gas Vapours, it can quickly become a Bad Day. Use at your own risk

 

[ShoestringMariner]

Harbour Freight probably has some Remote Triggers for very little money. With the Bare Wire, be very careful not to get too close the motor, cause if it sparks and there are Gas Vapours, it can quickly become a Bad Day. Use at your own risk

I was thinking about looking for a button style trigger

 

[flyingscott]

When were the carbs serviced last? Is the roller in good condition? Which way is the red lever on the primer facing? Have the carbs been adjusted at all? Your compression is probably fine as those blocks have decompression holes.

 

[ShoestringMariner]

When were the carbs serviced last? Is the roller in good condition? Which way is the red lever on the primer facing? Have the carbs been adjusted at all? Your compression is probably fine as those blocks have decompression holes.

Thanks. Service Unknown. I bought it used 2 years ago from a backyard marine mech. Hood is beat up & faded and covered in heavy shop dust. My guess is it was not well loved.
I have not touched carbs yet. Rebuild kits ordered.
Primer valve inline with primer body. Pointing to other end of primer

 

[bleb]

Following as I've got basically the exact same problem