Rebuilt Break-in

stockypower

Cadet
Joined
Jul 13, 2003
Messages
13
I just installed new rings and had cylinders honed out on a 1983 Johnson 175hp engine - blew a ring on one cylinder last season. I'm looking to put it into the water tomorrow and am looking for tips on a break-in period. All bearings were in good shape, re-used and place back the same way they came out (poor-man's rebuild). I fired the engine up and it sounds pretty good. thx
 
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DJ

Guest
Re: Rebuilt Break-in

stocky,<br /><br />Run a 25:1 oil to fuel ratio (one quart to six gallons, 87 octane) for at least 12 gallons.<br /><br />Nothing but idle the first hour. Very short bursts up to 3000 rpm, the second hour.<br /><br />From then on, up to ten hours, avoid WOT and vary speed often.
 

stockypower

Cadet
Joined
Jul 13, 2003
Messages
13
Re: Rebuilt Break-in

Thanks djohns - I thought that a higher octane rating would be better and I believe that is what they have down at the marina. Maybe I'll fill it up before I drop it in. Why the low octane? Will the 25:1 help break in the new rings?
 
D

DJ

Guest
Re: Rebuilt Break-in

stocky,<br /><br />Higher octane fuels tend to create deposits because they burn slower.<br /><br />The 25:1 will help seat everything and provide lubricant to wash away microscopic shavings, etc.
 
Joined
Jun 15, 2003
Messages
65
Re: Rebuilt Break-in

No need to go above 87 octane, unless it's a racing high perf. engine with a high compression ratio. Remember, octane retards the explosion. A difference will be minimal between octane, and in the end a waste of $$. (if your engine knocks under load then possibly raise octane)<br /><br />Some people say running 25:1 premix is bad, because in fact it is running the engine leaner (less gas because of more oil) Rich and lean is a fuel to air ratio.(if I'm not mistaken)<br />-Though, I would run a pre mix with a bit more oil in a break in period because of the increased friction. (the parts have to bed in)<br /><br />The main thing is take it easy, don't go at WOT. Remember it's not like a car where the engine is barely working to move itself on a level surface, with a boat it is like constantly going up a hill.<br /><br />Keep it in mind and good luck
 
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