OEM manufactures select appropriate spark plugs for the engine and vehicle type, so use the specified spark plugs.

I: High- performance spark plugs
X: Shape [type, IRIDIUM POWER]
W: Thread diameter and hex size
R: Internal Construction
16: Heat range
U: Shape [type]
E: Reach
11: Gap

High Performance Plug IW16EXR-U11
CodeCenter ElectrodeGround Electrode
F0.55 Iridium (needle to needle Iridium spark plugs)0.7 needle platinum
I0.4 Iridium (Iridium Power)U-groove
P1.1 Platinum (platinum spark plugs)With platinum tips
S0.7 Iridium (iridium spark plugs)With platinum tips
SV0.4 Iridium (iridium spark plugs)With platinum tips
V0.7 Iridium (Iridium Tough)With platinum tips
Z0.55 Iridium (iridium spark plugs)With platinum tips

Thread Diameter & Hex Size      IW16EXR-U11
CodeThread DiameterHex SizeApplicationCodeThread DiameterHex SizeApplication
M18mm25mmThread length 12mmQ*14mm16mmCompact plugs
L18mm22mmThread length 12mmQJ*14mm16mmSmall, projection spark plugs
MW18mm21mmThread length 12mmQL*14mm16mmSmall, long-torso housing plugs
MA18mm21mmTaper sheet, thread length 12mmS14mm21mmSurface Discharge spark plugs (for RE engines)
WF14mm21mmIridium Power (Ø 0.4), reach 12.7mmSF**14mm21mmSurface discharge spark plugs
UF10mm16mmIridium Power (Ø 0.4), reach 12.7mmT14mm16mmTaper seat
UH10mm16mmIridium Power (Ø 0.4), half threadsTR**14mm21mmOnly for marine
TF14mm16mmIridium Power (Ø 0.4), Tapered sheet, reach 11.2mmW**14mm21mm
J*14mm21mmProjection spark plugsN/A19mmCompact types
K*+14mm16mmSmall spark plugsX*12mm18mm
KJ*+14mm16mmSmall, projection spark plugsXU*12mm16mm
LP14mm21mmLPG spark plugsU*10mm16mm
P*14mm21mmPlatinum spark plugsU10mm14mmU20M-U only
Y*8mm13mm
Z1/2PF24mm

*Reach 19, +ISO type, **Reach 12.7

Heat Range          IW161EXR-U11
Denso914162022242729313234
NGK24567899.51010.511
Champion181612, 1110, 98, 763, 6159575553
Bosch10987, 65432

« Hot Type  |  Cold Type »

Reach IW16EXR-U11
CodeThread DiameterModel Examples
A19mm
Electrode position 7mm
21.5mm
J16AR-U11
B19mm
Electrode position 9.5mm
KJ20CR11
C19mm
Electrode position 5mm
K20DTR-S11
D19mm shroud 2W16EXR-U
E (with gasket)19mm
20mm
W25EBR
E (taper seat)18mmT16EPR-U
F13mmW20FP-U
FE19mm half threadsU24FER9
G19mm shroud 3
19mm shroud 3
X27GPR-U
PK20GR8
H19mm
Electrode position 9mm
27mm
QJ16HR-U

K16HPR-U11
L11mmW14L
M9mmU20M-U
N (taper seat)18mmT20NR-U11
V (taper seat)25mmPT16VR13
None10mm
11mm
19mm
19mm
22mm
W14M-U
L14-U
P16R
PK20PR11
S27
None (taper seat)8mm
11mm
11mm
T20M-U
T16PR-U
MA16PR-U
Shape (Type) IW16EXR-U11
CodeThread DiameterModel Examples
ADouble ground electrodesW22EA
ASlanted ground electrode (for racing)K29A-Z
AYDouble ground electrodes and special curved shapeJ16AY
BTriple ground electrodesW22EB
DFour ground electrodesW27EDR
KInsulator projection 1mmW16EK-S11
LMCompact type (20.6mm hex)W14LM-U
MType with shorter insulator head lengthW27EMR-C
MCompact type (19mm hex)W20M-U
NRacing type (nickel electrodes)W27EN
PtRacing type (platinum electrodes)W31EPT
PProjection (projection 1.5mm)W16EP-U
SNo projection (projection 0mm)W24ES-U
TDouble ground electrodesW20ET-S
TMDouble ground electrodesK22TM
TNDouble ground electrodesK22TNR-S
VSlanted ground electrodeQL22VR-ZU
XFull projection (projection 2.5mm)W16EX-U
-CGround cutbackW27EMR-C
-GLPlatinum center electrodeX22EPR-GL
-LRetracted insulator only for CVCC
Retracted insulator for motorcycles
Fine center electrode type for motorcycles
Heat-proof ground electrode type
W20ESR-L11
W14FP-UL
W20FR-L
U20FS-L
K20PR-L
-MGround electrode size increased
-NSpark plugs for Yamaha and KawasakiU24ESR-N
-PUses two layers of platinum for the ground electrode
Uses platinum for the center or ground electrode
PQ20R-P8
-SSemi-surface discharge typeQ20PR-P
-SAHalf high heat range type with semi-surface dischargeW20EPR-S
-TPPlatinum center electrode and ground electrode taper cutK20PR-TP
-UU-groove electrodeW16EX-U
-USUses star-shaped center electrodeW14-US
-VUltra-fine center electrodeW27ES-V
-Z0.7mm diameter platinum alloy center electrodeK29A-Z
-ZU0.7mm diameter platinum alloy center electrode and u groove
Ground electrode with taper cut
W27ES-ZU
Shape (Iridium Power)IU27A
CodeThread Diameter
ASlant electrode, no u-groove, no taper cut
BProjected insulator (1.5mm)
CNo u-groove
DNo u-groove, inconel ground electrode
ESStainless steel gasket
FSpecial
GStainless steel gasket
JProjected insulator (2.5mm)
KSpecial
LProjected insulator (2.5mm)
TFor lpg applications, strengthened insulator
X.8mm gap
Y.8mm gap
ZTaper cut
Internal ConstructionIW16EXR-U11
CodeShape
RWith register
NoneNo register
GAPIW16EXR-U11
CodeShape
80.8mm (0.032")
90.9mm (0.035")
101.0mm (0.040")
111.1mm (0.044")
131.3mm (0.050")
141.4mm (0.055")
151.5mm (0.060")
202.0mm (0.080")

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