8-14years should be looking at an 65cc 2 stroke, 85cc 2Stroke or 150cc 4Stroke. However, those who are slightly taller from 13years can ride a 125cc 2Stroke or 250cc 4Stroke. Those aged 16years+ can ride anything upwards of 125cc 2stroke – this is your own personal preference.

This based on the engine make up. A 2Stroke machine require oil being added to the fuel and produces its capacity output once every revolution of the engine. A 4Stroke machine uses straight fuel and has oil in the engine. As its name suggests, the machine produces its power output every other revolution of the engine. Therefore usually the engines double the capacity of a 2Stroke are considered to have similar horsepower output and are grouped together, known as MX1, MX2 classes, see below.

MX1 is known as the big bikes and are usually 250cc 2Strokes and 450cc 4 strokes, but realistically MX1 is anything above 145cc 2Stroke and 251cc 4stroke. MX2 is the smaller adult bike capacity class, usually 125cc 2strokes or 144cc 2strokes, and 250cc 4Strokes. MX2 is known is America as the ‘lites’ class. The kids class is known as the Inters or Inter Juniors.

Motocross events allow riders from 9years and up. See below for which class you can enter.

Inter Juniors Class and Age Capacities:

Age Grade Engine Capacity Only Wheel size / Spec
8 + Years Inter Junior Max 65cc 2 stroke 12 inch rear, 14 inch front
9 + Years Inter Junior Max SW85cc 2 stroke or SW150cc 4 stroke 14 inch rear, 17 inch front
11 + Years
Inter Junior

Max 85cc 2 stroke or 150cc 4 stroke 16 inch rear, 19 inch front
Junior/Senior/Expert Class and Age Capacities:

13 + Years MX2 (Junior/Senior/Expert) Max 145cc 2 stroke or 250cc 4 stroke –
15 + Years MX1 (Junior/Senior/Expert) Max 250cc 2 stroke –
15 + Years MX1 (Senior/Expert) Max 450cc 4 Stroke –
17 + Years MX1 (Junior/Senior/Expert) Min 146cc 2 stroke or 251cc 4 stroke