Rering rebuild complete

[Todd Humphreys]

I recently reringed my 1982 75hp Johnny, cranked up the first try. I doubled the oil and did two 30 min sessions of idling on the muffs, with great results. Yesterday I eagerly went down to the Amite River (closest landing) to complete my break in procedure. Idle was about 1400 rpm in neutral, idle in gear was 900 rpms. For the next hour I ran the motor in various rpms never holding it at full throttle until the last ten minutes but only in 20 second bursts. I have a 1981 16' (19' w/ fan tail X 54" wide) Sport Lafitte skiff with fan tail (weight ???) before rebuild WOT was 5000, now WOT was 6100 rpm and only holding that for about 5 seconds. My engine range is 5200 - 5800. I had my self and my two boys (ages 4 & 8) in for the ride (total people weight 400#). I presume that the rings are not completely broke in, can I assume that the rpm will increase slightly as compression increases. BTW the motor has an OMC 13x19 prop with cup.

 

[OBJ]

Re: Rering rebuild complete

Sounds like a good rebuild Dad. Just a couple things....<br /><br />Idle is a tad high. 1400rpms at idle will cause a thunk going into gear....not good on the gear and clutch dog lobes. Ya' might want to idle it down a bit. Idle in gear should be 650 to 750rpm...if the think tank is remembering right.<br /><br />You might want to verify all the rpms with a reliable tach, like a timing gun with tach. Compare it with the tachometer reading in the rig. This is just to make sure your rpms are accurate. Go from there on the operational range.

 

[R.Johnson]

Re: Rering rebuild complete

I would not look for an increrase in RPM with engine time. Ring seat, is an old time term that simply refuses to die. There is very little break-in time with a two cycle, what with it's roller, and needle bearing constuction. If properly assembled, the engine can be run right from the start. The new Johnson & Evinrude engines don't even address break-in time. If not put together correctly, an engine will break-apart, long before it will break-in.