Spark Plugs & how to read them 1981 - 2001

[JezR31]

i will be using these to shortenthe words i use:

REC P = Recommended Plug

IRID = IRIDIUM

for the R30 owners

1981 - 1985 L24E

Recommended Plug - BP5ES-11

IRIDIUM - BPR5EIX-11

1981.8 - 1985.8 L20ET

REC P - BPR5EIX-11

IRID - BPR5EIX-11

1983.2 - 1985.8 FJ20ET

REC P - BP6ES-11

IRID - BPR6EIX-11

R31s +

1985.8 - 1987.8 RB20DE

REC P - PFR5A-11

IRID - BCPR5EIX-11

1985.8 - 1987.8 RB20DET

REC P - PFR5A-11

IRID - BCPR5EIX-11

1986 + RB30E

REC P - BCP6ES-11

IRID - BCPR6EIX-11

1986 - 1988 RB30ET

REC P - BCPR6ES-11

IRID - BCPR6EIX-11

1987.8 - 1989.11 RB20DE

REC P - PFR6A-11

IRID - BCPR6EIX-11

1987.8 - 1989.5 RB20DET

REC P - PFR6A-11

IRID - BCPR6EIX-11

1989.5 - 1991.8 RB20DET

REC PFR5A-11

IRID - BCPR5EIX-11

1991.8 - 1993.8 RB20DE

REC P - PFR6A-11

IRID - BCPR6EIX-11

1991.8 - 1993.8 RB20DET

REC P - PFR6A-11

IRID - BCPR6EIX-11

1991.8 - 1993.8 RB25DE

REC - PFR5K-11

IRID - BCPR5EIX-11

1993.8 - 1998.5 RB25DE

REC - PFR5G-11

IRID - BKR5EIX-11

1993.8 - 1998.5 RB25DET

REC - PFR5G-11

IRID - BKR5EIX-11

1998.5 - 2001.6 RB25DET

REC - PFR6G-11

IRID - BKR6EIX-11

1989.8 - 1995.1 RB26DETT

REC - PFR6A-11

IRID - BCPR6EIX-11

1995.1 - 1999.1 RB26DETT

REC - PFR6A-11

IRID - BCPR6EIX-11

1999.1 + RB26DETT

REC - PFR6A-11

IRID - BCPR6EIX-11

www.ngk.com.au

[JezR31]

The "Reading the Plugs" part.

NORMAL

Light grey or tan deposits and slight electrode erosion.

CARBON FOULING

Dry, soft black carbon on the insulator and electrodes.

Symptoms:

- Misfiring

- Poor starting

- Faulty acceleration

Causes:

- Delayed ignition timing

- Faulty choke - over rich air/fuel mixture

- Bad ignition leads

- Plug heat range too cold

PRE-IGNITION

A melted or burned center and/or ground electrode, blistered insulator and aluminum or other metallic deposits on the insulator.

Symptoms:

- Pre-ignition occurs when combustion begins before the timed spark occurs

- Loss of power causing engine damage

Causes:

- Plug insufficiently tightened

- Engine insufficiently cooled

- Ignition timing too advanced

- Plug heat range too hot

OVER HEATING

An extremely white insulator with small black deposits and premature electrode erosion.

Symptoms:

- Loss of power at high-speed or during heavy load

Causes:

- Plug insufficiently tightened

- Engine insufficiently cooled

- Plug heat range too hot

- Ignition timing too advanced

MECHANICAL DAMAGE

Bent electrode an a broken insulator, dents often present on electrode.

Symptoms:

- Misfiring

Causes:

- Plug nose is too long for engine head

- Foreign object (bolt/nut) in combustion chamber

OIL FOULING

Wet, oily black deposits on the insulator and electrodes.

Symptoms:

- Poor starting

- Misfiring

Causes:

- Wrong piston rings, cylinders, and valve guides

- Fuel mixture oil content too high (two-stroke engines)

BROKEN INSULATOR

Insulator is cracked or split.

Symptoms:

- Misfiring

Causes:

- Severe detonation

- Incorrect tool/torque applied during installation or removal

- Careless gap setting

TORCHED SEAT

Melted in the thread and seat area of the plug housing.

Symptoms:

- Loss of power causing engine damage

Causes:

- Plug insufficiently tightened