Yamaha YZF R125 top end removal

   

                             Yamaha YZF R125 Workshop Manuals on Ebay UK 

Yamaha YZF R125 top end barrel cylinder piston removal 

Removing the top end is easy the only thing to remember is how to set timing on rebuild which is not difficult .

⚠️ SAFETY FIRST: Ensure the engine is cold and the cooling system has been fully drained before starting. Improper handling of the timing chain can lead to serious engine damage.

Follow this step-by-step guide to removing the top end of your Yamaha YZF-R125. This tutorial covers the disassembly of the rocker cover, cylinder head, and barrel, as well as crucial tips for managing the timing chain and sprocket.

Key Technical Highlights:

• Head Removal: Accessing and removing the main cylinder head bolts and the two auxiliary Allen head bolts.

• Timing Chain Management: Technique for holding the flywheel bolt to undo the timing gear and using string to prevent the chain from falling into the crankcase.

• Tensioner Removal: How to properly loosen and remove the timing chain tensioner.

• Component Access: Guidance on removing the rocker cover and water pump to expose the internal top-end assembly.

---

Torque Specifications & Technical Data

To ensure a correct rebuild, keep these torque settings and measurements in mind:

• Cylinder Head Bolts (M8): 22 Nm (2.2 m·kg, 16 ft·lb) — Tighten in two stages in a criss-cross pattern.

• Cylinder Head Bolts (M6): 10 Nm (1.0 m·kg, 7.2 ft·lb)

• Camshaft Sprocket Bolt: 30 Nm (3.0 m·kg, 22 ft·lb)

• Timing Chain Tensioner Bolts: 10 Nm (1.0 m·kg, 7.2 ft·lb)

• Rocker Cover Bolts: 10 Nm (1.0 m·kg, 7.2 ft·lb)

Pro Tip: Always use new gaskets for the cylinder head and cylinder base during reassembly to prevent oil or coolant leaks. When removing the piston, place a clean rag over the crankcase opening to prevent the circlips from accidentally falling into the bottom end.

Remove the rocker cover bolts 

this exposes the main cylinder head bolts

Remove water pump see our post here on that 

these 2 allen head bolts need to be removed as well 

Here I am holding the flywheel bolt to undo the timing chain 

bolt .

below the timing chain tensioner is loosened and then  removed 

you can now free the timing chain i hold it with string to avoid dropping it into

engine

I have now removed the timing chain sprocket as I needed to 

and I am undoing the top cylinder head main bolts 

pulling head free while controlling chain 

now remove chain guides 

and prepare cylinder barrel for removal 

again control chain while lifting of barrel 

See R125 cylinder head removel refitting video here 

                 R125  Timing gear / cam gear and chain removel 

                                  and refitting video below 

Need new or used barrel / head  / pistons / timing chains etc etc

try here on Ebay UK 

see more Yamaha YZF R125 blog posts