Yamaha YBR 125 Engine Removal Guide (2026 Update)

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Safety Message: Removing an engine involves handling heavy components and flammable fluids. Always work on a level surface, ensure the bike is secure on a center stand, and use a secondary jack to support the engine weight. Disconnect the battery to prevent electrical shorts and work in a well-ventilated area to avoid fuel vapors.

Whether you are performing a full bottom-end rebuild or swapping in a fresh motor, removing the engine from a Yamaha YBR 125 (or the newer YS125) is a manageable task for a home mechanic. The frame is a "diamond" type, meaning the engine is a stressed member, so proper support is vital during the process.

1. Essential Tools & Equipment

Before you start unbolting the frame, ensure you have these essentials ready to make the job safer and faster:

• Motorcycle Scissor Jack / Engine Stand – Crucial for supporting the engine weight as you slide out the mounting bolts.

• Impact Wrench (Cordless) – Makes quick work of stubborn, road-grimed engine mounting bolts.

• Replacement High-Tensile Bolt Kits – If your original bolts are rusted or "necked," replace them during reassembly.

2. The Pre-Removal Checklist

1. Drain the Oil: It is much easier to do this while the engine is still in the frame.

2. Disconnect the Battery: Remove the negative (-) terminal first to avoid sparks near the fuel tank.

3. Remove the Bodywork: Take off the side panels and seat to gain clear access to the wiring loom and airbox.

4. Fuel System: For Carb models, turn the petcock to 'OFF' and drain the bowl. For EFI models, depressurize the fuel line before disconnecting the quick-release coupling.

3. Step-by-Step Removal

• Drive System: Remove the front sprocket cover and the chain. Do not lose the small metal spacer behind the sprocket!

• Exhaust: Unbolt the header nuts from the cylinder head. These are often rusted—apply penetrating oil 24 hours in advance.

• Electrics: Disconnect the stator wires, the gear position sensor, and the spark plug cap. Label your connectors with masking tape.

• Cables: Disconnect the clutch cable from the crankcase arm and the throttle cable(s) from the carb/throttle body.

• Mounting Bolts: There are three main mounting points. Support the engine with your jack, then remove the lower rear bolt, the upper rear bolt, and finally the front down-tube bolts.

4. 2026 Tip: Managing the Weight

The YBR 125 engine weighs approximately 25kg to 28kg (approx. 60 lbs). While it is light compared to a superbike engine, it is awkward to handle alone. Once the bolts are out, wiggle the engine toward the right-hand side of the bike to clear the frame rails.

5. Reinstallation Note

When putting the engine back in, always start the threads of all mounting bolts by hand before tightening any of them. This ensures the engine is aligned correctly in the frame. Torque the main M10 mounting bolts to 45 Nm – 55 Nm (check your specific year's manual for exact values).

                                          Disconnect the battery

unplug fuel hoses and electrical connectors to remove tank 

undo exhaust bolts , very careful as these can shear 

off and cause problems !! if they are tight work them out 

forwards and backward slowly .

Drop oil if not already done so 

slacken and remove clutch lever cable at lever

and engine 

undo all wiring 

undo front engine mount bolts

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undo airfilter and inlet manifold and move out of way remove altogether is even better

rag inside the inlet to prevent items entering 

undo the remaining engine mount bolts and wiring connectors 

dont forget to remove starter lead cable 

upper engine mount 

thats about it easy , lower engine to floor job done 

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