Don Terrill’s Speed-Talk

Disassemble the motor, put about a .050"-.060" radius at the bottom of each cylinder, rewash thoroughly and reassemble.

Doing otherwise may risk having the motor disassembling itself, without your consent.

MTENGINES wrote: ↑Wed Mar 07, 2018 6:05 am

j-c-c wrote: ↑Tue Mar 06, 2018 10:22 pm Does a sharper edge vs any radius wipe any splashed oil off skirts better and with a more favorable result?

Yes the sharper edge does a better job at wiping oil, along with aluminum from the piston.

So maybe a visible test for this would be in the case of a sharp edge removing any piston skirt coatings?

We should keep in mind that the protrusion is less than 3/16"; it's not like the wrist pin is coming into view...

The edge does not feel sharp.

MadBill wrote: ↑Wed Mar 07, 2018 5:08 pm We should keep in mind that the protrusion is less than 3/16"; it's not like the wrist pin is coming into view...

That is what I am thinking.... it is not like some strokers I've seen where half the piston is falling out of the hole.

And an inadeqately chamfered cylinder in one of those will do a very fine job of removing metal from the thrust face of the skirt!

It's all relative to the skirt design/length and where that particular pistons gauge point was designed/located. Some very short skirt pistons gauge points can be damned near the bottom of the skirt. What's the specific part #? Look up the spec's or call the mfgr.

Then add the potential for a lower gauge point with the fact that the bottom of the bore has not been radiused on major minor thrust and you can easily score skirts and bore during cold starts. As things wear out it doesn't usually get any better either. Just imagine how that cold piston flops around when the motor goes vroom on every startup.