Motocross
The only liquid cooled four stroke mini race bike. Races in the 85 class, revs like a small 250F, and needs to be serviced like one. Sold in Australia from 2007 to 2026, 20 model years.
The CRF150R is the four stroke answer to the 85cc two strokes. It is a proper race bike with a liquid cooled, four valve engine, a five speed gearbox, real suspension and disc brakes. The RB Expert version has bigger wheels for taller kids. It makes its power smoothly, which makes it easier for a junior to ride fast, and it has been essentially the same bike since 2007.
It suits a junior who finds an 85 two stroke too snappy, or a family that already knows four strokes. The trade off is servicing: it is a small high revving four stroke and it wants pistons and valve checks the way a 250F does.
Treat it like a small 250F. Oil every 5 to 8 hours of racing with a 10W 40 full synthetic (it takes well under a litre, so check the manual), air filter every ride, and valve checks at the interval in the table. Plan on a piston around 30 to 40 hours for a bike that races, and do not run it past that because the bottom end pays for it.
Keep the coolant fresh and the radiators straight; a mini with a bent radiator boils in a hurry.
Chains, sprockets, filters, oil, brake pads, grips, levers and tyres for the CRF150R are in the MWMX Parts Store, with member pricing. Shop parts for this bike →
Ask about the last piston and the last valve check, and get receipts. Make sure it starts easily (it is kick start only) and idles cleanly hot. Check the frame around the footpegs and the subframe for crash damage. A CRF150R that has been raced hard by a fast junior and never had a piston is a rebuild waiting to happen.
Recent sold prices are on the Marketplace page linked below.
None listed right now. Selling one? List it free →
Tight valves mean hard starting. Check them on time.
A race bike wants a piston every 30 to 40 hours. It is the running cost of the class.
A hard starting CRF150R wears out a small rider. Fresh valves, a clean carburettor and good technique fix it.