1957 evinrude big twin 35 low power

eolsen

Seaman
Joined
May 7, 2014
Messages
67
I don't seem to have full power. Also I cannot lower the throttle to low speed it just dies. I have to stay in the throttle area from start to fast. Any input would be appreciated.....
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
check you have spark on both cylinders
Also do a drop test, (try seeing if its only one cylinder working by pulling each plug off the motor in turn, noting the difference, then replacing, sounds like its running on one cylinder
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
I agree it could be on one cylinder.
Also there is a low speed and high speed mixture adjust needle valves.
Initial setting on Idle valve needs too be one turn out from gently bottomed,
High speed initial setting is 3/4 turn out from gently bottomed.
You may have to remove the knobs to do the initial settings.
Once the motor is warmed these need to be adjusted at the appropriate speed.
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Step 1: Test Compression. That motor should be roughly 100 psi per cylinder, and even.

Step 2: Test spark: It should jump a 1/4" gap on an inline tester with a bright blue ZAP

Step 3: Ensure linc n sync is set, as well as carb settings as mentioned.

Things to note: If the coils are original, they are junk and need to be replaced. My guess is they are.
 

eolsen

Seaman
Joined
May 7, 2014
Messages
67
It ended up being one if the cutoff switch wires heading to the magneto. It now runs on two cylinders!
 
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