Spark Plug - Honda 450X 2005 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 (DENSO)
Optional IFR9H11
VK27PRZ11 (DENSO)
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.
• Use only a "wire-type feeler gauge" to check
the spark plug if necessary. 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.
Spark Plug Replacement & Inspection
1. Remove the seat and fuel tank (page 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
(NGK) or
(1) spark plug cap

(2) spark plug

5. Check the electrode 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
(1)
(2)
(4)
(3)
Spark Plug
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.
If you're using a new plug, ride for at least ten
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 twise 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.
10. Connect the spark plug cap.
11. Install the fuel tank and seat (page 38).
Servicing Your Honda
61