Honda GX 120 Tech Manual page 15

PISTON NOTES
Piston will be stock Honda standard size and will not be altered in any way.
A. Oversized pistons must not be used.
B. All three piston rings must be used and installed properly.
1. Top ring: Chrome compression ring installed with "N" or "T" on rail up. No expander under ring.
2. Middle ring: Oil scraper ring installed with "N" or "T" on rail up. No expander under ring.
3. Bottom ring: Three (3) piece oil rings are allowed.
C. Piston may not be knurled, grooved or coated.
D. Piston weight: 106 grams minimum.
E. Total Piston weight: With rings, pin, and clips - 121 grams minimum.
F. Total Piston weight with rings, retainers, complete with rod, pins and bolts 263 grams minimum.
G. See drawing for dimensions
RINGS
A. Must be stock Honda rings with stock size and configuration.
B. No decreasing of ring tension by heating, machining or any other means.
C. Ring thickness:
Compression: 0.056" min.
Scraper: 0.056" min.
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