Setting the ignition timing of a kart engine is often done by setting the height of the piston before top dead center and aligning the ignition system to a specific mark on the crankshaft. The extension adapters you can find for sale are expensive and unnecessary (at least for water cooled engines).

I know this works for a TM Racing engine, but I imagine most water cooled two-strokes as well.

You may need to tune your x-y hole compensation to get the fit just perfect from your printer and material.