Too little oil seizes the engine. Too much fouls the plug and smokes. Premix bikes only — Honda NC50 / PA50II use oil injection (see Honda guide).
| Ratio | Oil per Gallon | When to Use |
|---|---|---|
| 50:1 | 2.6 oz | Stock daily riding, quality synthetic |
| 40:1 | 3.2 oz | Break-in, light tuning |
| 32:1 | 4.0 oz | Kitted builds, racing, air-cooled abuse |
| 25:1 | 5.1 oz | Break-in only (first tanks on fresh bore) |
By Platform
| Engine | Typical stock | Notes |
|---|---|---|
| Puch E50 / ZA50 | 50:1 | Richer for break-in or 70cc kits (32:1–40:1). See Puch guide. |
| Tomos A35 / A55 | 50:1 | Quality synthetic; richer if kitted. Chain drive — see Tomos guide. |
| Peugeot 103 | 50:1 | European tuners often run 40:1 on performance builds. |
| Motobécane AV7 | 50:1 | Stock exhaust is restrictive; tune oil with jetting changes. |
| Minarelli V1 bikes | 50:1 | General, Cimatti, etc. — same premix rules. |
| Honda NC50 / PA50II | N/A premix | Oil injection tank — do not premix fuel unless pump removed. |
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