Yamaha YZ125

The YZ125 is where a huge number of Australian riders learn to race. It weighs next to nothing, it forces you to carry corner speed, and a top end costs less than a set of tyres. The aluminium frame arrived in 2005 and the KYB SSS fork in 2006, and the bike stayed nearly the same until a proper update in 2022 brought a new top end, a new pipe and modern bodywork.

It suits a junior stepping up from an 85, a lightweight adult, or anyone who wants a race bike that costs nothing to own. Against the KTM 125 SX it is a touch slower and lacks electric start, but it is much cheaper used and easier to find parts for at any dealer.

Premix at 32:1 to 40:1 with a good full synthetic, gearbox oil every 5 to 10 hours (it takes around 700 ml), air filter every ride. A 125 lives on the rev limiter so it wants top ends more often than a 250: rings every 15 to 20 hours and a piston every 30 to 40 for a race bike. Clean the power valve at every top end.

Keep the reeds, the plug and the jetting fresh because a 125 that is even slightly off is slow. Grease the linkage and swingarm bearings, and check the spokes on a junior bike because they get ridden hard and washed harder.

Look for a bike from a family that raced it and serviced it, and ask for receipts for the last top end. Do a compression test if you can. Check the frame around the footpegs and the subframe for cracks and bent rails, because these bikes get crashed a lot by learning riders. A bent pipe, torn seat and scratched plastics are cosmetic; a rattly bottom end is not.

Recent sold prices for each year are on the Marketplace page linked below.