The sparkplugs used in the older Honda motorcycles were made by the NGK company of Japan. A typical plug used would have a designation of:
B-8ES
where the "B" stood for the thread size, "8" was the heat range, "E" was the reach and "S" was the type of plug.
- Thread diameters reffered to the size of the hole in the engine block and ranged from 10 mm to 14 mm for all older bikes.
- Heat range referred to the amount of heat built up in the tip of the plug. If the ceramic collar was deeply recessed, the plug ran hot because it could not transfer its heat to the surrounding metal. If the collar was short, the heat could be transferred away and thus the plug ran cooler.The heat range was normally 7 or 8 with only a few high performance bikes using a 9.
- Reach referred to the length of the threaded part of the plug. The reach was either E (19 mm-3/4 in) or H (12.7 mm-1/2 in) for all bikes.
- Type of plug referres to the general use or electrode type of the plug. All standard bikes used the S "super wide range electrode" type of plug because of its ability to handle most engine demands.
|
A |
18 mm thread (diameter) |
|
B |
14 mm thread (diameter) |
|
C |
10 mm thread (diameter) |
|
D |
12 mm thread (diameter) |
|
XP |
projected insulator (follows thread size) |
|
XU |
surface discharge (follows thread size) |
|
XR |
resistor (follows thread size) |
|
2 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
13 |
| HOTTEST | MEDIUM | MEDIUM | COLDEST |
|
E |
19 mm (3/4 inch) |
|
F |
taper seat |
|
H |
12.7 mm (1/2 inch) |
|
L |
11.2 mm (7/16 inch) |
|
blank |
12 mm (for A thread) |
|
blank |
9.5 mm [3/8 inch] (for B thread) |
|
C |
Competition |
|
M |
Mazda rotary |
|
N |
Racing (nickel electrode) |
|
P |
Racing (platinum electrode) |
|
S |
Super wide range electrode |
|
V |
File wire (gold electrode) |
|
W |
Tungsten electrode |
|
X |
Booster gap |
|
SL |
1/2 step colder than listed |
|
B-9EV |
CR250M,CR125M |
|
B-8ES |
CB/CL450,CB/CL360,CB/CL/SL350, MT250,MT125 |
|
B-7ES |
XL175 |
|
D-8HS |
CA/CB77(12mm head),CL77, CA/CB72(12mm head),CL72, CA/CB/CL/SL125, CA/CB/CL160, CA95(12mm head) |
|
D-8ESL |
CB750,CB350F,XL350,XL250, CB/CL200,XL/TL/SL125, |
|
D-7ES |
CB550,CB500 |
|
D-6HS |
CM91,S/CL/ST90 |
|
C-7HS |
CA/CB77(10mm head), CA/CB72(10mm head), |
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