Every 4000 Miles (6000 Km) Or 6 Months; Spark Plugs - Check And Adjustment - Yamaha TDM850 User Manual

i.io Every 4000 miles (6000 km) or 6 months

Every 4000 miles (6000 km) or 6 months

2 Spark plugs -
check and adjustment
1 Make sure your spark plug socket is the
correct size (18 mm) before attempting to remove
the plugs - a suitable one is supplied in the
motorcycle's tool kit which is stored under the
seat.
2 On XTZ models, remove the fuel tank and the
air filter housing (see Chapter 4).
3 Using compressed air if available, clean the
area around the base of the spark plugs to
prevent any dirt falling into the engine when the
plugs are removed.
4 Check that the cylinder location is marked on
each plug lead, then pull the spark plug cap off
each spark plug (see illustration). Using either
the plug tool supplied in the bike's toolkit or a
deep socket type wrench, unscrew the plugs from
the cylinder head (see illustration). Lay each
plug out in relation to its cylinder; if either plug
shows up a problem it will then be easy to identify
the troublesome cylinder.
5 Inspect the electrodes for wear. Both the
centre and side electrodes should have square
edges and the side electrodes should be of
uniform thickness. Look for excessive deposits
and evidence of a cracked or chipped insulator
2.4a Remove the spark plug cap...
2.8b Using a feeler gauge to measure the
spark plug electrode gap
around the centre electrode. Compare your spark
1
plugs to the colour spark plug reading chart at
the end of this manual. Check the threads, the
JSj
washer and the ceramic insulator body for cracks
and other damage.
6 If the electrodes are not excessively worn, and
if the deposits can be easily removed with a wire
brush, the plugs can be re-gapped and re-used (if
no cracks or chips are visible in the insulator). If
in doubt concerning the condition of the plugs,
renew them, as the expense is minimal. Yamaha
do not specify a renewal interval, but leave it to
the discretion of the owner.
7 Cleaning spark plugs by sandblasting is
permitted, provided you clean the plugs with a
high flash-point solvent afterwards.
8 Before installing the plugs, make sure they are
the correct type and heat range and check the
gap between the electrodes (see illustrations).
Compare the gap to that specified and adjust as
necessary. If the gap must be adjusted, bend the
side electrode only and be very careful not to chip
or crack the insulator nose (see illustration).
Make sure the washer is in place on the plug
before installing it.
9 Since the cylinder head is made of aluminium,
which is soft and easily damaged, thread the
plugs into the heads turning the tool by hand
(see illustration). Once the
2.4b ... then unscrew the spark plug
2.8c Adjust the electrode gap by bending
the side electrode only
plugs are finger-tight, the job can be finished with
a spanner on the tool supplied or a socket drive
(see illustration 1.4b). If a torque wrench can be
applied, tighten the spark plugs to the specified
torque setting. Otherwise tighten them by 1/4 to
1/2 turn after they have been fully hand-tightened
and have seated. Do not over-tighten them.
recessed, you can slip a
|Tflfl|33 -As the plugs are quite
HINT
short length of hose over the end of the
plug to use as a tool to thread it into place.
The hose will grip the plug well enough to
turn it, but will start to slip if the plug begins
to cross-thread in the hole - this will prevent
damaged threads.
10 Reconnect the spark plug caps, making sure
they are securely connected to the correct
cylinder. Install all other components previously
removed. .
PIJHJHS Stripped plug threads in the HUIUSJ
cylinder head can be
repaired with a Heli-Coil ' insert -
see Tools and Workshop Tips' in the
Reference section.
HiMT
2.8a Using a wire type gauge to measure
the spark plug electrode gap
2.9 Thread the plug in as far as possible by
turning the tool by hand
Scaned by Stalker