Spark Plug - Honda CRF250R 2005 Owner's Manual

Spark Plug

Refer to Safety Precautions on page 19.
Spark Plug Recommendation
The recommended standard spark plug is
satisfactory for most racing conditions.
Standard R0409B-8 (NGK)
For extend high
R0409B-9 (NGK)
speed riding
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 the 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.
54
Servicing Your Honda
Spark Plug Replacement & Inspection
Refer to Safety Precautions on page 19.
1. Remove the seat and fuel tank (pages 29,30).
2. Disconnect the spark plug cap (1).
3. Clean any dirt from around the spark plug bases.
4. Remove the spark plug (2).
(1)
(1) spark plug cap

(2) spark plug

5. Check the electrode for wear or deposits, the
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:
0.024 – 0.028 in (0.6 – 0.7 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.
If you're using a new plug, ride for at least ten
minutes before taking a plug reading; a brand-new
(2)
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 (page 122).
Check the carburetor, fuel system and ignition
timing.
8. 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: 1/2 turn after it seats.
b) Then loosen the plug.
c) Next, tighten the plug again:
1/8 turn after it seats.
9. Connect the spark plug cap.
10. Install the fuel tank and seat (page 31).
(4)
(3)