① Apply a thin layer of engine oil to the piston pin. You should be able to push the piston pin into the bushing with your palm without a sense of gap, in order to meet the requirements of tightness.

② Apply some engine oil to the piston pin, put it into the Isuzu Engine, and clamp the piston pin on a bench vise padded with copper (the clamping force should not be too large to avoid damage to the parts).

First, pull the connecting rod in the direction of the piston pin. There should be no sense of gap, and there should be no bubbles between the piston pin and the bushing; when rotating the connecting rod, the connecting rod should be able to rotate smoothly; when the connecting rod and the plane become 75, it should be able to stop. When you tap it gently with your hand, the connecting rod should slowly drop by its own weight.

When checking the fit of the Bare Engine on the bench vise, move back and forth along the axial direction of the connecting rod. If there is a sense of gap, or the connecting rod falls too fast in the self-fall test, it means that the piston pin and the connecting rod pin bushing are loose.

If bubbles appear when pulling back and forth along the axial direction of the piston pin on the bench vise, it means that the Bare Engine has a flare or the gap is too large. If you encounter the above situation, do not force it to use.

Try a piston pin with a slightly larger diameter in the same level, or replace the new bushing and re-hinged; if the fit is too tight, it should be scraped and repaired.