Cummins/Onan — Honing Procedure

Repair & overhaul · Cylinder bore

From a Cummins/Onan service manual — check it applies to your exact model before use.

Applies to: Cummins/Onan MCCK

Procedure

1. Use a hone to rebore cylinder. Remove stock to 0.002 inch (0.051 mm) less than finished bore with coarse hone (100 grit), then complete with finish hones (300 grit).
2. Anchor block solidly for vertical or horizontal honing.
3. Use drill press or heavy-duty drill operating at about 250 to 450 rpm.
4. Lower hone into cylinder until it protrudes 1/2 to 3/4 inch (13 to 19 mm) past end of cylinder.
5. Rotate adjusting nut until stones contact cylinder wall at narrowest point.
6. Loosen adjusting nut until hone can be turned by hand.
7. Connect drill to hone and start drill.
8. Move hone up and down in cylinder about 40 cycles per minute.
9. Usually work bottom of cylinder first because it is smaller.
10. When cylinder takes uniform diameter, move hone up and down all the way through bore.
11. Follow hone manufacturer's recommendations for wet or dry honing and oiling hone.
12. Check diameter of cylinder regularly during honing.
13. A dial bore gauge is easiest; check size at six places: twice at top, middle and bottom at 90 degree angles.
14. When cylinder is about 0.002 inch (0.051 mm) within desired bore, change to fine stones and finish bore.
15. Finish should have crosshatch scratches forming an angle of 23 degrees.

Full service-parts list: Cummins/Onan MCCK →

Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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