1991 yamaha 40 rebuild

[bullbat]

just finished rebuilding me 40 yammy last night gonna go put the lower unit on today and fire her off, ne one know what the proper breakin procedure would be??

 

[Mas]

Re: 1991 yamaha 40 rebuild

Two-stroke right? The procedures are the same as a new motor. Check your owner's manual for break-in, but the following generic procedure I found in my Evinrude manual can be used.

Enrich the fuel/Oil ration to 25:1 for the FIRST 12 gallons of fuel (after 12 gallons, use 50:1 ratio).

First 20 minutes: Operate the motor in the water, in gear with a load at fast idle

Next 40 minutes: operate below 1/2 throttle...changing throttle every 15 minutes. Use higher rpms only to get boat on a plane, then reduce below 1/2 throttle while maintaining planing speed.

Check/clean plugs

Next nine hours: operate below 3/4 throttle...with every 30 minutes operate at WOT for only ONE minute

Replace plugs

I hope this helps,

MAS

 

[deejaycee_2000]

Re: 1991 yamaha 40 rebuild

You don't have to go that extreme .... just mix the oil about 40:1 and keep revs under 3000rpm for that tank, from there onwards you can go on as per normal ....