Yamaha YZ85

The YZ85 is the bike in the 85cc class that dealers always have parts for and that every club has ten of. It got a proper update in 2019 with a power valve engine and a new frame, and again in 2021 and 2022 with a new fork and bodywork. The LW big wheel version adds a 19 inch front and 16 inch rear for taller kids.

It suits a junior from about 11 to 15 moving up from a 65, or a lightweight rider who wants a cheap and simple race bike. The KTM 85 SX has the edge on outright speed but the Yamaha is easier to ride, easier to own and cheaper used.

Premix at 32:1 to 40:1, gearbox oil every 5 to 10 hours (about 500 ml), air filter every ride. An 85 lives at full throttle, so a racing junior wants rings every 10 to 15 hours and a piston every 20 to 30. Clean the power valve on the 2019 onwards bikes at every top end.

Check the spokes and the chain adjusters often, because these bikes get ridden hard and adjusted rarely. Grease the linkage and steering head every few months.

Buy a bike that a family raced and serviced, with receipts. A compression test tells you most of what you need to know about the engine. Check the frame around the footpeg mounts, the subframe and the radiators for crash damage. Most YZ85s have been down many times; the question is whether anything is bent.

The 2019 onwards bikes hold their value well. Recent sold prices are on the Marketplace page linked below.