1975 1980 20R Cylinder Head:
- Round Intake Port / Round Exhaust Port
- 80 / 81cc Chamber
- In. Valve Dia. 43mm / Ex. Valve Dia. 35mm
1981 / 84 22R / RE Cylinder Head:
- Square Intake Port / Round Exhaust Port
- 82 /83 cc Chamber
- In. Valve Dia. 44.5mm / Ex. Valve Dia. 36.5mm
1985 / 95 22R / RE Cylinder Head:
- Square Intake Port / Pear Shaped Exhaust Port
- 58 cc Chamber or 22RET (Turbo)
- In. Valve Dia. 44.5mm / Ex Valve Dia. 36.5mm
Cylinder Head Intake Air Flow (Aprox):
- Stock: 130 CFM
- Stage 2: 160 CFM
- Stage 3: 200 CFM
- Stage 5: 250 CFM
