07-09-2018 08:02 - edited 07-09-2018 08:03
Seafoam is not an Evinrude approved chemical. If you think there is carbon buildup, use Evinrude's Engine Tuner which comes out like a foam and has a lubricant in it, unlike a straight solvent that can wash the oil off of bearings and cylinder walls.
Your 115 HP has a movable flapper down inside the mid-section that tunes the exhaust for better acceleration and top speed. If that is stuck or inoperative, the motor will feel like it lost power. See your dealer who can quickly check its operation.
"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.