Whether you are restoring a classic 2005 Carburetor YBR or maintaining a late-model 2017 Fuel Injected (Fi) commuter, precision data is the difference between a reliable ride and a breakdown. This technical archive is the ultimate "survival bible" for the Yamaha YBR 125 (ED, Custom, and Factor), providing the exact specifications required for professional-grade maintenance.
The Ultimate Commuter, Decoded.
Whether you’re a first-time rider on a 2005 carburetor model or a seasoned commuter keeping a fuel-injected 2016 unit alive, the YBR 125 is the backbone of the road. But even the world’s most reliable workhorse needs the right care.
The YBR 125 Bible is a centralized technical hub designed to take you beyond the basic owner’s manual. We bridge the gap between "it won't start" and a perfect ride with:
Deep-Dive Specs: Detailed data for every generation (2005–2017).
Common Fixes: Solving the "missing" high-RPM issues and transmission wear.
Restoration Guides: From frame-up refreshes to simple bolt-on upgrades.
Don’t just ride it—master it.
The YBR 125 used a Mikuni carburetor from 2005 to 2006. From 2007 onwards (Euro 3 compliance), Yamaha switched to Electronic Fuel Injection (EFI). EFI models are more fuel-efficient and reliable in cold starts, while Carb models are easier for home mechanics to tune without diagnostic tools.
This is a common "ghost" issue often caused by a restricted fuel filter (on EFI models) or a failing ignition coil. Checking the spark plug gap (0.6–0.7mm) and cleaning the air filter usually resolves 80% of top-end bogging issues.
Use a high-quality 10W-40 4-stroke motorcycle oil (JASO MA or MA2 spec). Because the YBR has a wet clutch, avoid "Energy Conserving" car oils, as they can cause clutch slippage.
Engine Type: 124cc, Air-cooled, 4-stroke, SOHC, 2-valve.
Bore x Stroke: 54.0 mm x 54.0 mm.
Compression Ratio: 10.0 : 1.
Max Power: 7.5 kW (10.1 PS) @ 7,800 rpm.
Transmission: 5-speed, Constant Mesh.
Front Tyre: 2.75-18 42P.
Rear Tyre: 90/90-18 57P.
Front Brake: Single Disc, Ø 245 mm.
Rear Brake: Drum, Ø 130 mm.
Wet Weight: 124 kg (including full oil and fuel tank).
Engine Oil Capacity: 1.0 Litre (Total); 0.95 Litre (Periodic change).
Fuel Tank Capacity: 13 Litres (including approx. 3.4L reserve).
Valve Clearance (Cold): Intake 0.08–0.12mm / Exhaust 0.10–0.14mm.
Idling Speed: 1,300–1,500 rpm.