Spark Plug - Honda CRF450X 2017 Owner's Manual & Competition Handbook

Refer to Safety Precautions on page 25.
Spark Plug Recommendation
The recommended standard spark plug is
satisfactory for most racing conditions.
Standard IFR8H11
VK24PRZ11
Optional IFR9H11
VK27PRZ11
Use only the recommended type of spark plugs in
the recommended heat range.
NOTICE
Using a spark plug with an improper heat range
or incorrect reach can cause engine damage.
Using a non-resistor spark plug may cause
ignition problems.
This motorcycle uses a spark plug that has an
iridium tip in the center electrode and a platinum
tip in the side electrode.
Be sure to observe the following when servicing
the spark plug.
• Do not clean the spark plug. If an electrode
is contaminated with accumulated objects or
dirt, replace the spark plug with a new one.
• To check the spark plug gap, use only a "wire-
type feeler gauge." To prevent damaging
the iridium tip of the center electrode and
platinum tip of the side electrode, never use a
"leaf-type feeler gauge.''
• Do not adjust the spark plug gap. If the gap
is out of specification, replace the spark plug
with a new one.
17 CRF450X̲31MEY710.indb 61 17 CRF450X̲31MEY710.indb 61
Spark Plug Inspection & Replacement
1. Remove the seat and fuel tank (pages 36, 37).
2. Disconnect the spark plug cap (1).
3. Clean any dirt from around the spark plug base.
4. Remove the spark plug (2).
(NGK) or
(DENSO)
(NGK) or
(DENSO)
(1)
(1) spark plug cap

(2) spark plug

5. Check the electrodes for wear or deposits,
the sealing gasket (3) for damage, and the
insulator for cracks. Replace if you detect
them.
6. Check the spark plug gap (4), using a
wire-type feeler gauge. If the gap is out of
specifications, replace the plug with a new
one.
The recommended spark plug gap is:
0.039 – 0.043 in (1.0 – 1.1 mm)
(3) sealing gasket
(4) spark plug gap
7. To obtain accurate spark plug readings,
accelerate up to speed on a straightaway.
Push the engine stop button and disengage
the clutch by pulling the lever in.
Coast to a stop, then remove and inspect the
spark plug. The porcelain insulator around
the center electrode should appear tan or
medium gray.
(2)
If you're using a new plug, ride for at least 10
minutes before taking a plug reading; a brand-
new plug will not color initially.
If the electrodes appear burnt, or the insulator is
white or light gray (lean) or the electrodes and
insulator are black or fouled (rich), there is a
problem elsewhere.
Check the carburetor, fuel system and ignition
timing.
8. With the sealing gasket attached, thread
the spark plug in by hand to prevent cross-
threading.
9. Tighten the spark plug:
• If the old plug is good:
1/8 turn after it seats.
• If installing a new plug, tighten it twice to
prevent loosening:
a) First, tighten the plug:
NGK: 3/4 turn after it seats.
DENSO: 1/2 turn after it seats.
b) Then loosen the plug.
c) Next, tighten the plug again:
1/8 turn after it seats.
(4)
NOTICE
An improperly tightened spark plug can damage
(3)
the engine. If a plug is too loose, a piston may be
damaged. If a plug is too tight, the threads may
be damaged.
10. Connect the spark plug cap. Take care to
avoid pinching any cables or wires.
11. Install the fuel tank and seat (pages 36, 38).

Spark Plug

61
Servicing Your Honda
2016/06/08 11:45:47 2016/06/08 11:45:47