Evinrude 25 HP ID..2 questions

[Riverrat43]

Hello, New member here. I recently purchased an Evinrude 25 HP, Tiller Steer, Elec Start outboard motor. There is no ID tag anywhere on the motor. I'd like to get a shop manual, but am uncertain of the year. The person I bought it from also bought it used and he said he "thought" it was about a 1980 model. It has a splined prop, exhaust is not thru the prop, short shaft, small(thin style) lower unit ( or so I'm told).The coil/plug wires have tags on them saying " Use Champion LV78 plugs". Can anyone tell me how to ID the correct year model? Second Question: I'm told either the carburator or both carburator and intake can be changed out with the 35HP motor. Does this apply to non thru the hub exhaust engines? Thanks in advance for any help. I'm sure I'll learn a lot reading this forum.

 

[rickdb1boat]

Re: Evinrude 25 HP ID..2 questions

Look on the powerhead for a welsh plug about 1" in diameter. Post any numbers on that plug. (Looks like a freeze plug).

 

[Riverrat43]

Re: Evinrude 25 HP ID..2 questions

Thanks....didn't see the plug, but DUHHHH, did see a sticker under the cowling that I missed before...it says " 1979 25HP spark advance 34 degress"...guess that answers the question.

 

[rickdb1boat]

Re: Evinrude 25 HP ID..2 questions

It happens! Glad you found it. I do not know the answer to your second question, but someone will come along with it.. Just hang in there. It takes time for the other guys to respond sometimes, especially on the weekends..

 

[Riverrat43]

Re: Evinrude 25 HP ID..2 questions

Well, now that I know it's a 79 model, I still have a question regarding changing out the carb with one from a 35 HP. Would any year other than 79 work? Would a larger diameter prop be needed with a different pitch in order to avoid over revving? Would just the carb need changing or would an intake also be needed? Any info would be appreciated.

 

[G DANE]

Re: Evinrude 25 HP ID..2 questions

Hi Riverrat 43<br /><br />Those are good motors, some of the best they ever build, if in decent shape. Same block for 20 - 35HP. Difference in HP comes from:<br />20 - 25 HP = Different carb, 20 HP carb has nylon limiter, and different cylinderhead, at least on models later than 84.<br />25 - 35 HP = Different intake manifold on all, and different carb on models later than 84. Different midsection and lowerunit with thru-hub exhaust on all models. Replacing your carb without replacing intake manifold will give you no feelable increase. Even replacing both manifold and carb will only give you very little increase in performance as long as you havnt got the midsection and lowerunit, that makes breating better. Hope this answers your question.