2-Stroke Fuel Pre-Mix Ratio Calculator & Master Oil Chart
Instantly calculate exact 2-stroke premix oil volumes in U.S. fluid ounces (`fl oz`), milliliters (`mL` / `cc`), and pints across 24:1, 32:1, 40:1, 50:1, and 60:1 fuel ratios for competition motocross and enduro machines.
1. Master 2-Stroke Pre-Mix Ratio Chart (U.S. Gallons → Fluid Ounces & mL)
Standard U.S. workshop reference table based on 1 U.S. Gallon = 128 Fluid Ounces (3,785 mL):
| Ratio (Oil %) | 1 Gallon | 2 Gallons | 2.5 Gallons | 3 Gallons | 4 Gallons | 5 Gallons |
|---|---|---|---|---|---|---|
| 24:1 (4.0%) | 5.33 oz (158 mL) | 10.67 oz (315 mL) | 13.33 oz (394 mL) | 16.00 oz (473 mL) | 21.33 oz (631 mL) | 26.67 oz (789 mL) |
| 32:1 (3.0%) | 4.00 oz (118 mL) | 8.00 oz (237 mL) | 10.00 oz (296 mL) | 12.00 oz (355 mL) | 16.00 oz (473 mL) | 20.00 oz (591 mL) |
| 40:1 (2.4%) | 3.20 oz (95 mL) | 6.40 oz (189 mL) | 8.00 oz (237 mL) | 9.60 oz (284 mL) | 12.80 oz (379 mL) | 16.00 oz (473 mL) |
| 50:1 (2.0%) | 2.56 oz (76 mL) | 5.12 oz (151 mL) | 6.40 oz (189 mL) | 7.68 oz (227 mL) | 10.24 oz (303 mL) | 12.80 oz (379 mL) |
| 60:1 (1.6%) | 2.13 oz (63 mL) | 4.27 oz (126 mL) | 5.33 oz (158 mL) | 6.40 oz (189 mL) | 8.53 oz (252 mL) | 10.67 oz (315 mL) |
| 80:1 (1.2%) | 1.60 oz (47 mL) | 3.20 oz (95 mL) | 4.00 oz (118 mL) | 4.80 oz (142 mL) | 6.40 oz (189 mL) | 8.00 oz (237 mL) |
2. Metric 2-Stroke Pre-Mix Ratio Chart (Liters → Milliliters / cc)
Metric fuel container reference table based on 1 Liter = 1,000 Milliliters (cc):
| Ratio | 1 Liter | 5 Liters | 10 Liters | 15 Liters | 20 Liters |
|---|---|---|---|---|---|
| 24:1 | 42 mL (1.4 oz) | 208 mL (7.0 oz) | 417 mL (14.1 oz) | 625 mL (21.1 oz) | 833 mL (28.2 oz) |
| 32:1 | 31 mL (1.1 oz) | 156 mL (5.3 oz) | 313 mL (10.6 oz) | 469 mL (15.9 oz) | 625 mL (21.1 oz) |
| 40:1 | 25 mL (0.8 oz) | 125 mL (4.2 oz) | 250 mL (8.5 oz) | 375 mL (12.7 oz) | 500 mL (16.9 oz) |
| 50:1 | 20 mL (0.7 oz) | 100 mL (3.4 oz) | 200 mL (6.8 oz) | 300 mL (10.1 oz) | 400 mL (13.5 oz) |
| 60:1 | 17 mL (0.6 oz) | 83 mL (2.8 oz) | 167 mL (5.6 oz) | 250 mL (8.5 oz) | 333 mL (11.3 oz) |
| 80:1 | 13 mL (0.4 oz) | 63 mL (2.1 oz) | 125 mL (4.2 oz) | 188 mL (6.3 oz) | 250 mL (8.5 oz) |
3. Factory 2-Stroke Ratio Baselines by Engine Displacement & Riding Discipline
50cc / 65cc / 85cc Youth Motocross (KTM SX, YZ65/85, KX65/85)
Small-bore engines run sustained wide-open throttle at extreme piston speeds and rely heavily on abundant residual oil film across the lower rod needle bearing and exhaust bridge.
125cc / 150cc Competition Motocross (Yamaha YZ125, KTM 125/150 SX, Husky TC 125)
High-load sand and loam MX tracks benefit from 32:1 (4.0 oz/gal) to maximize ring-to-wall sealing and heat transfer from the piston crown to the Nikasil cylinder wall.
250cc Competition Motocross (Yamaha YZ250, KTM 250 SX, GasGas MC 250)
32:1 is standard for high-speed motocross; 40:1 (3.2 oz/gal) is widely used for mixed track/trail riding with full-synthetic ester 2T oils to minimize power-valve carbon deposits.
250cc / 300cc Technical Enduro & Woods (KTM 250/300 XC-W, Husky TE 300, Beta 300 RR)
Technical low-RPM singletrack generates lower exhaust gas temperatures (EGT). Running 50:1 (2.56 oz/gal) or 60:1 (2.13 oz/gal) with JASO FD synthetic oil prevents spark plug fouling and silencer drool.
Carburetor Stoichiometry Warning: Oil Ratio vs. Air-Fuel Ratio (AFR)
In a carbureted 2-stroke dirt bike, both gasoline and premix oil must pass through the same brass main jet and pilot jet orifices. Because oil is more viscous and displaces liquid gasoline volume per unit of air:
• Adding MORE oil (e.g., switching from 50:1 to 32:1) LEANS the Air-Fuel Ratio (less gasoline passes through the jet per stroke).
• Adding LESS oil (e.g., switching from 32:1 to 50:1) RICHENS the Air-Fuel Ratio (more gasoline passes through the jet per stroke, while reducing crank/ring lubrication). Always verify spark plug insulator color and jetting when changing premix ratios.