new to boating-engine question

[UTTOM]

I was out on the lake yesterday breaking in a newly rebuilt Johnson 70 hp by puttering around at various RPM's. I was going to out the boat on a sandy shore at a local restaurant. I put the engie in IDLE and raised it to keep it form hitting the bottom. It was out of the water for maybe 15-20 seconds when I realized it was still running. I then turned it off and beached the boat.

Did I do any substantive damage for the amount of time it was out? It seems to run strong afterwards, but I was hearing a vibration. It may be something rattling in the boat. The warning horn (chirps when the key is turned on) did not activate.

On another note, how many RPM's would the motor generate at 1/2 throttle and 3/4 throttle.

Thank you.

 

[rockyrude]

Re: new to boating-engine question

The direct answer to your question is probably not. You just don't want to do it often. Your wot rpm should be about 5200 so half would be 2600. Also, search for the correct break-in, you don't break them in like cars.

 

[UTTOM]

Re: new to boating-engine question

Thank you.

I was told by the mechnaic to vary the RPM's for the first hour but not to exceed 1/2 throtltle. Then 1-2 WOT then go back to varying the RPM's for the next 1-2 hours, but still below wide open.

 

[tashasdaddy]

Re: new to boating-engine question

your WOT should be more toward 5500-5800.

 

[UTTOM]

Re: new to boating-engine question

OK. I found some proceedures on the web that are fairly parallel to my instructions. Now that I have read the WOT RPM's and the 1/2 way point, do you think that much damage can be done if I went to slightly higher RPM's?

I had the boat out 2 months ago for maybe 30 minutes. Alot of that time was in a no wake zone and only after that, not very many RPM's. I say that becuasae the boat did not have a tachometer at the time (does now), but I was very hesitant to give it much throttle. I was learning how a boat throtle works. Far different reaction time that an airplane throttle.

Yesterday, it took 10 minutes to putter out of the no wake zone, and then I just got it up on plane and backed down the throttle. I reached about 3,300 RPM's and I varied it between 2,600 - 3,300 RPMs for the next 30-45 minutes. Then 1 minute wide open, then back to between 2,500-3,500 for another 30-45 minutes.

 

[tashasdaddy]

Re: new to boating-engine question

you are fine, hope you are running double oil, if using auto mixing pump, mix your tank 50:1 to double oil, during break in period.

 

[wesley pipes]

Re: new to boating-engine question

well to be on the safe side after a rebuild you should run a 25:1 oil ratio in your tank or if it has an oiler 50:1 in the tank and the rpms all differ based on the prop pitch and speed ect.

 

[UTTOM]

Re: new to boating-engine question

I am running 25:1 (or maybe a tad more towards 20:1) for good lubrication for the first 18 gallon tank, then 50:1 after the first tank.