05-27-2020 07:41 - edited 05-27-2020 07:45
The current 115 HO is a G2 1.9L 3 cylinder engine which is a completely different design than a V4 115.
You may be meaning the older 115 and 115 HO V4 from years past. If so, then the cylinder blocks have different part numbers than the 90 HO meaning that they are not the same internally. Most likely compression and porting are different between the two engines as well as the EMM software.
"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.