Break in, how many tanks of gas?

[voodoo]

89 Johnson 65, new bore, pistons, rings, rod bearings. How many tanks of gas before I can treat it as broken in?
Also is it better to let it run below 5000 rpm at part throttle or keep it between 5 and 6 thousand despite the throttle?
Thanks.

 

[Barnacle_Bill]

Re: Break in, how many tanks of gas?

I wish my memory was better but I do remember a total of 10 hours. The first few keep RPMs low and varied. As you get more hours on it you can run it faster but don't run at the same RPMs for a long time. As you get closer to the 10 hours you can run it WOT for short periods of time. That worked for me with a rebuilt 90 Johnson.

 

[Alby1]

Re: Break in, how many tanks of gas?

Prob to late for this reply.

About 6 to 10 hours. Use 25 to 1 mix. Run it a idle for the first 30 Minutes. Then just above idle for a while. Don't leave the motor run at constant speeds for a prolong period of time. Rev it up to 2 or 3 thousand rpm occasionally during it's break-in.

 

[voodoo]

Re: Break in, how many tanks of gas?

2-3000? Wouldn't that do more harm than good? Isn't 50 to 1 the maximum to run it at?

 

[hoeser]

Re: Break in, how many tanks of gas?

If your machinist did not give you a break in procedure, I would follow the 10 hour procedure which is roughly as follows:

Mix 50:1 in the tank if you have a working VRO system (this ultimately gives you about 25:1)

Mix 25:1 in the tank if you do not have VRO.

First 10 minutes, idle or slightly fast idle

Next 50 minutes less than 3500rpm

Next 2 hours 75% throttle with brief spurts at WOT (less than 3 minutes)

The rest: no prolonged exposure to WOT, vary engine speed every 15 minutes.

You definitely want double oil for the whole 10 hours.

 

[voodoo]

Re: Break in, how many tanks of gas?

Seloc recommends 50 to 1 during break in. I have no VRO. They are very specific on never running at richer than 50 to 1.
I'm confused, wouldn't 25 to 1 just lean it out and foul it up?

 

[hoeser]

Re: Break in, how many tanks of gas?

The terms "Rich" and "Lean" don't have anything to do with the amount of oil in your fuel, they are applied to the mixture of air to your fuel. Lean being more air rich being more fuel.

I'm not sure how you arrived at the conclusion that running 25:1 will lean fuel/air mixture, it will not. You want 25:1 - Seloc is either wrong or you are reading it incorrectly.

 

[voodoo]

Re: Break in, how many tanks of gas?

Oil doesn't burn the same way as gas, so if you add enough oil to the mixture, it will actually make a motor run hotter, not colder as one would assume with more oil.
I did follow the basic stuff you said. Probably 5, 5 min runs on muffs. The first hour was pretty easy.
Now it's half to 3/4 throttle, varied often, with short 5 second bursts of wot.
It started at 100 psi, now I have 112 across all 3.
All three plugs are a beautiful light tan.
Funny thing is when I bought the boat, it had a motor freshly rebuilt by a marina.
They did a horrible job and it never had any more that 100 psi.
I am still trying to puzzle out running 25/1. It just seems like way too much oil.

 

[Alby1]

Re: Break in, how many tanks of gas?

You want more oil when breaking in a engine. When the break in is done, then go 50 to 1, or your manufactures requirements. Breaking in an engine with 50/1 can cause the rings not to seat proper and possible cylinder wall scoring.

 

[hoeser]

Re: Break in, how many tanks of gas?

Voodoo, you seem to be thinking outside the outboard world. I realize in a lot of 2-stroke applications such as dirtbikes, snowmobiles, etc, the oil is mixed the same as post break in. It's not the same here. Do not be concerned with increased engine temperature. Outboards already run *way* colder than the aforementioned 2-stroke land vehicles and are under a considerably heavier load.

Doubling the oil will not increase your combustion temperatures by a measure of which you need to be concerned... running insufficient oil during break in will however increase your overall engine temperature due to increased friction across fresh metal surfaces.