STL SmallBore Blog post: MiniMoto Series

Engine Modification Classes

System for referencing common engine upgrades for 125cc Honda MiniMoto’s


  • Stage 1: (Stock Bore 125cc)

    • Stage1/Tier1 (S1T1) - Intake, Exhaust, and Tune.

    • Stage1/Tier2 (S1T2) - S1T1 + Camshaft.

    • Stage1/Tier3 (S1T3) - S1T2 + High Compression Piston.

    • Stage1/Tier4 (S1T4) - AKA “Super125” - S1T3 + Race head (Ported and/or Big valves, intake, injector, etc.)

  • Stage 2: Medium Bore Kits - (intake / exhaust / tune is assumed for this stage)

    • Stage2/Tier1 (S2T1) - 150cc or less big bore kit

    • Stage2/Tier2 (S2T2) - S2T1 + Camshaft

    • Stage2/Tier3 (S2T3) - AKA “Super### - S2T2 + Race Head (Ported and/or Big valves, intake, injector, etc.)

  • Stage 3: Big Bore Kits - (intake / exhaust / tune / supporting modifications are assumed for this stage)

    • Stage3/Tier1 (S3T1) - 2 Valve BBK

    • Stage3/Tier2 (S3T2) - 4 Valve BBK

    • Stage3/Tier3 (S3T3) - DOHC BBK


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- TJ (STL Smallbore) Dec, 2021