Motorcycle Owners Club

Honda CG125 but also some universal motorcycle information

Honda CG125 Valve Clearance Step 5

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Ignore all of steps 5 (5, 5.1, 5.2, 5.3) if you have the front drum brake model.

5. To remove the valve cover
you first need to remove the air suction valve (see picture below) that's connected to the valve cover
(it's on top of the engine, left hand side)


5.1 Slide the rubber air pipe up and out of the metal hook on the bikes metal frame (underneath the petrol tank).


5.2 Remove the two bolts (10mm) that connect the air suction valve to the valve cover.

Alternative Picture 1 (air suction valve removed)

Alternative Picture 2 (valve cover with air suction valve removed)

5.3 Remove the two bolts (8mm) that connect the air pipe to the top of the valve cover (pipe has a rubber washer),
slide air suction valve + pipes away from valve cover / bike.

If the spanner cannot grip,
try a better quality spanner or warm the bike up and try again
(then let the bike cool down overnight again before checking the valve clearance)
or remove the petrol tank and use a socket (which may need an extra thin extension shaft)
(a socket will grip the nut far better and tighter than any spanner).

To remove the petrol tank
Make sure the petrol on / off / reserve tap is in the off position
detach the petrol fuel hose from the petrol on /off / reserve tap
remove the left hand side panel of the bike and unclip the right hand side panel where it clips in to the petrol tank
unclip the petrol tanks electrical connection and un hook the wire from the bikes metal frame
remove the seat (2 nuts underneath the rear mud guard on the sides), then remove the bolt holding the tank,
remove the tank by pulling it towards rear of the bike and up

The 10mm bolts in 5.2 and the 8mm bolts in 5.3 have identical sized threads and length.
I had real trouble getting a spanner to grip the 8mm bolt in the middle of the valve cover.
So I put the 10mm bolt from the right hand side of 5.2 in its place (10mm is much easier to grip with a spanner).
I put the 8mm bolt in to the hole that the 10mm bolt came out of;
I was able to use an 8mm socket (I had to use the extension shaft and adapter in the socket set to reach).
The 8mm socket gripped the 8mm bolt perfectly
(be careful not to over tighten since you have far more leverage than with a spanner).
The 10mm bolt might be technically called a 10mm Hex Flange Bolt M6 x 16mm
(thread needs to be on the entire length of the bolt).
16mm is the thread length.

Step 6 (back to main Valve Clearance page)