28 HP rough run, where to go next, video included

[diveman05]

Recently picked up this motor and have been doing some basic maintenance to it while we've been in lock down so its ready for the summer.

It starts up fairly well, the electric choke had been removed by previous owner.

Misses ever now and then, esp. in mid range, see the video for examples.

2 New plugs
2 New Coils
New plug wires
took the carb off and cleaned and replaced, set the valve at 1.5 turns per the other thread on here.
Checked compression, both cylinders around 110


Seems to idle pretty good, and seems ok at higher RPMS, but mid range it has a miss.

Should I look at fuel or spark next do you think? Anything super obvious I missed?

https://www.youtube.com/watch?v=qx-1yXDiZ3o&feature=youtu.be

 

[tblshur]

diveman05 i would do a cylinder drop test check spark with an adjustable spark tester is the choke still missing?

 

[diveman05]

diveman05 i would do a cylinder drop test check spark with an adjustable spark tester is the choke still missing?

I will do a drop test and spark test in the morning, neighbors probably wouldn’t like it too much now.

the electric choke Solenoid is still missing, the fuel line goes direct from the pump to the carb, the 2 little lines that it appears went to the choke have been cut and plugged

 

[racerone]

Not good to wind it up in neutral.----Sounds like it might be running on one cylinder.

 

[F_R]

That thing is lean sneezing. A couple of theories:

1. Possibly all it needs is a tweak to the left on the slow speed knob
2. Possibly the carb throttle pickup is too soon.
3. Possibly you are "confusing" it by running at high RPM in neutral/no load.

 

[jimmbo]

When you say you cleaned the Carb, did you R&R the welsh type disks, cleaning the areas they covered?
When you reinstalled the Carb, did you verify the Sync between the Carb and the Spark Timing?

 

[diveman05]

Thank you everyone so far for the advice, I will be working on it today. I don't like reving it in the tank but our great governor has shut down all the boat launches until May 1st so I'm kind of stuck in my driveway!

 

[oldboat1]

So don't rev in the tank!

 

[F_R]

BTW, by "confusing" it, what I meant was under such conditions it is developing abnormal pressures in the intake manifold and crankcase, which lead to unpredictable results. But one predictable result is the chance of engine runaway--an uncontrolable high speed revving.

 

[diveman05]

BTW, by "confusing" it, what I meant was under such conditions it is developing abnormal pressures in the intake manifold and crankcase, which lead to unpredictable results. But one predictable result is the chance of engine runaway--an uncontrolable high speed revving.

I made the mixture a little richer today and it seemed to idle/run better. I've kept the RPM's lower per everyones advice, so I can't take it out until they open the boat launches in Michigan on May 1st hopefully.

I did a spark test and found both the upper and the lower we're able to jump the 7/16th fairly easily.

Tried dropping one cylinder at a time, top cylinder the engine sputtered a little but kept running,

bottom cylinder it died shortly after.

both coils are brand new, so i switched them and the problem followed,

will follow the other thread to test the coil to make sure it is good and i didn't get a bad new one.

After that I'm thinking pull the flywheel, make sure everything is good and clean under there, then onto timing