Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this
Re: Mercury 150 Ring Gap .040 (STD) on honed cylinder within tolerance - is this
Well, the "usual" break in of a motor is supposed to take 20 hours. So you can assume at that time, the parts have 'run in' to a sufficient level that they have become 'acclimated' to each other.<br /><br />But you're confusing the need to have a cross-hatched surface for the rings to 'bite' into upon first run-in, with the conditions that a motor that's well-broken-in will experience.<br /><br />Once the parts have seated-in, things will of course get smoother. That doesn't mean that a well broken-in cylinder which has a smooth 'mirror-finished' surface is beginning to fail. To the contrary, the fit between the piston rings and cylinder walls is getting better. Of course as the motor accumulates a lot of time on it, there will be actual wear to the cylinders, but I expect you'll find that the majority of 2-stroke outboards are never run to the point of just flat 'wearing out' but experience other problems such as overheating, use of poor quality oil which leads to ring scuffing, or other issues such as water intrusion or detonation, to the point of failure.<br /><br />So, what the cross-hatch is doing for you is facilitating the intitial seating of the rings. <br /><br />If you don't de-glaze the cylinders you may find that the rings never break in properly and may fail prematurely. The cylinder walls are TOO smooth and will not properly wear the microscopic 'high spots' off the new rings which prevents them from seating.<br /><br />Don't get too an*l about the process, I used to use Marvel Mystery oil as a lube, also WD-40, no adverse affects regardless. In the old days I didn't have the benefit of these forums and just honed the old Mercs out until they looked right. You can readily see and feel the difference between a non-honed and honed cylinder, you'll see the nice even cross-hatches and can feel them with your fingernail, in comparison to the very smooth surface of an unhoned cyl wall.<br /><br />You only want to hone out until you 'clean' up the cylinder and get a uniform pattern of cross-hatches. Beyond that you're just wearing out the bore unnecessarily.<br /><br />You wouldn't believe what I did to my old 1000 Merc and it still lived many many hours of hard water-skiing, and lots of fishing time after I sold it. As long as you don't go crazy you should get good results. I usually would place the hone in the cyl and then start the drill. Stop the drill in the bore then remove it. Just visualize the pattern you're making as you move your arm up and down, and you should be able to get close to that 'ideal' cross-hatch. If it's not perfect, it should still work as it's far better than an unhoned cylinder.<br /><br />Anyway, HTH & Happy Honing.........ed
<br /><br />-W