I’ve answered these questions in an email, but I’ll put this here, just in case there’s a very slight outside chance that somebody else might need Lockwood specifications also.

The specs for the Ace are basically as follows;

Piston Ring diameter – 2.100" diameter, width .1245/.125", end gap .005"/.010"

Piston skirt clearance – My books do not show the actual piston-to-bore clearance, but for two-cycle water cooled engines, the rule of thumb I’ve always used is .002" of clearance for each inch of bore diameter.

As an example – An Evinrude Sportfour has a similar piston diameter (actually 2.00 inch diameter), and the spec for clearance is min 0.0025" and max 0.004", so the book spec is actually tighter than my ROT, but you get the idea.

I’d say for the Ace, even if the clearance checks out to be as much as 0.006" it should be fine. If the skirt clearance checks out to be 0.006" to 0.008", you might be OK, but may have to hone the cylinder lightly and go to 0.005" oversize rings.

Crankshaft Journals – top, bottom, and connecting rod journal diameters are all .874/.875". Recommended clearance on all three is 0.0015"/.003".

Wrist pin clearance – If you can limit the clearance between the wrist pin and rod to no more than 0.002", so much the better.

Hope this helps.

Best,
PM T2