Johnson / Evinrude thermostat replacement - YouTube Click to view on Bing14:07Mar 20, 2018Johnson / Evinrude thermostat replacement Dangar Marine. Loading.. Unsubscribe from Dangar Marine? Cancel Unsubscribe. Working.. Subscribe Subscribed Unsubscribe 106K.Author: Dangar MarineViews: 67K Where is the thermostat for a 25hp Johnson outboard motor? The 1987 model, 25 hp Johnson outboard requires a 50:1 ratio. One pint of 2 cycle oil, to six gallons of fuel.