Pit Bike Big Bore Kits
Stage 1, Stage 2 & stroker big bore kits for Honda CRF50, XR50, CRF70, XR70, Z50, CT70 & more
Bump displacement from stock to 88cc, 108cc or 117cc — modern and vintage Honda 50/70 platforms
Big Bore Kits for Honda 50 & 70 Pit Bikes
Complete big bore and stroker kits for Honda CRF50, XR50, CRF70, XR70, Z50, CT70, ATC70, TRX70, SL70, and XL70. Kits are available in Stage 1 and Stage 2 configurations, with stroker options that take displacement well beyond a standard big bore. Modern (1988-up) and vintage (1968-1981) platforms covered separately — make sure you order for the right generation.
Modern Honda 50/70 — 1988 & Up
Stage 1 Big Bore Kit — Z50, XR50, CRF50 — Entry level big bore for the modern Honda 50 platform.
Stage 2 Big Bore Kit — Z50, XR50, CRF50 — More aggressive build with higher compression and performance components.
Stage 1 Big Bore Kit — XR70, CRF70 — Stage 1 kit for the Honda 70 platform.
Stage 2 Big Bore Kit — XR70, CRF70 — Higher output Stage 2 kit for XR70 and CRF70.
88cc Big Bore Kit with Race Head — Z50, CRF50, XR70, CRF70 — Complete kit with performance race head for maximum output.
Vintage Honda 50/70 — 1968 to 1981
Stage 1 Vintage Big Bore Kit — Z50, CT70, ATC70, TRX70, SL70, XL70
Stage 2 Vintage Big Bore Kit — Z50, CT70, ATC70, TRX70, SL70, XL70
88cc Vintage Big Bore Kit with Race Head — Z50, CT70, ATC70 1968-81
Stroker Kits — Maximum Displacement
108cc Stroker Kit 1 — CRF50, XR50, CRF70
108cc Stroker Kit 2 — Honda 50/70
117cc Stroker Kit 5 — CRF50, XR50, CRF70
117cc Stroker Kit 6 with Race Head — CRF50, XR50, CRF70
Performance Upgrades
Performance Camshaft — Honda CRF50 — Upgrade cam for modern CRF50 big bore builds.
Performance Camshaft — Honda Z50 1968-1981 — Vintage Z50 performance cam.
High Volume Oil Pump — Honda 1982-Up — Recommended upgrade when building a big bore or stroker engine.
High Volume Oil Pump — Vintage Z50 1969-1981 — Same upgrade for vintage Honda builds.
