Yamaha YZF-R125 Service Manual: Checking the ignition spark gap
1. Check:
Ignition spark gap
Out of specification
Perform the
ignition
system troubleshooting, starting with step 5.
Refer to "TROUBLESHOOTING" on page
8-3. 
NOTE:
If the ignition spark gap is within specification, the ignition system circuit is operating normally.
a. Disconnect the spark plug cap from the spark plug.
b. Connect the ignition checker "1" as shown.
2. Spark plug cap
c. Set the main switch to "ON" and the engine
stop switch to "
".
d. Measure the ignition spark gap "a".
e. Crank the engine by pushing the start switch
" 
" and gradually increase the
spark gap until
a misfire occurs.
Checking the ignition coil
1. Check:
Primary coil resistance
Out of specification Replace.
a. Disconnect the ignition coil connectors from
the ignition coil terminals.
b. Connect the pocket tester ( × 1)
to ...
Checking the crankshaft position sensor
1. Disconnect:
Crankshaft position sensor coupler
(from the wire harness)
2. Check:
Crankshaft position sensor resistance
Out of specification Replace
the crankshaft
position senso ...
Other materials:
Checking the connections
Check the leads, couplers, and connectors for
stains, rust, moisture, etc.
1. Disconnect:
Lead
Coupler
Connector
2. Check:
Lead
Coupler
Connector
Moisture → Dry with an air blower.
Rust/stains → Connect and disconnect several
times.
3. Check:
All co ...
Checking the brake fluid level
1. Stand the vehicle on a level surface.
NOTE:
Place the vehicle on a suitable stand.
Make sure the vehicle is upright.
2. Check:
Brake fluid level
Below the minimum level mark "a" → Add the
recommended brake fluid to the proper level.
A. Front brake
B. Rear brake
WA ...
VInstalling the handlebars
1. Stand the vehicle on a level surface.
WARNINGSecurely support the vehicle so that there
is
no danger of it falling over.
2. Install:
Front brake master cylinder "1"
Front brake master cylinder holder "2"
Front brake light switch
NOTE:
Install the brake master cyl ...