Evinrude E-NATION, for those dedicated to water, power, fishing and fun
Posts: 1
Registered: ‎07-31-2011

cylinder compression

I have a 1986 johnson 225 hp the cylinder compresion is around 80 to 85 on all 6 cylinders it run s great out of the water with the muffs on but in the lake as soon as you drop the foot down it starts to load up then die 

Posts: 9,047
Registered: ‎07-14-2011

Re: cylinder compression

Those compression numbers are a bit low, but since they are fairly close to even, it may be your gauge accuracy.


Your motor is 25 years old so there may be an accumulation of wear on the throttle shafts, rings, pistons, crankcase seals, etc. that factor into things. You have to be sure the ignition system is strong enough to jump a 7/16" air gap at cranking speed, the spark and throttle linkage is synchronized by the book, the engine is warming up correctly at the correct idle speed, and that the recirculation system consisting of hoses, fittings, and check valves is clean and operational. At the same time the carburetor jets and passageways have to be clean and the floats are adjusted correctly. Any air leaks or used gasket problems will affect the idling of the motor. Be sure to check the primer valve for internal leakage that can make your motor run too rich. Decarbonizing may help the idle by freeing up any lightly stuck piston rings for better sealing.




"There is never just one thing wrong with a boat";
                    -- Travis McGee, main character in a book series by John D. McDonald 



The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.

The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.