NGK BPMR7A spark plug: gap, thread size, what NGK lists it for and equivalents

The NGK BPMR7A spark plug comes gapped at 0.7 mm (0.028 in) by NGK, with a 14 mm thread, 9.5 mm (3/8 in) reach and a 19 mm (3/4 in) hex. Some makers set it tighter: Stihl's MS 170/180 and Husqvarna's 372 XP manuals give 0.5 mm, so use your manual's gap. We sell the NGK BPMR7A 5-pack and 10-pack.

NGK Australia lists it mostly for chainsaws, brushcutters, trimmers and blowers. If you only needed the size, the table below has the rest and you can stop there.

NGK BPMR7A specs

Source: NGK (Niterra EMEA) part finder entry for the BPMR7A (thread, reach, hex, gap) and NGK's "How to read our part number" chart in the NGK Spark Plugs and Glow Plugs 2017/2018 catalogue (heat range, resistor, projected insulator), both read 30 September 2026. The inch values are from our BPMR7A listing, which also gives a 1.25 mm thread pitch and a gasket seat.

What NGK lists the BPMR7A for, and what it doesn't

NGK Spark Plugs Australia's part finder lists the BPMR7A as the plug for 1,069 entries in its commercial and industrial section (read 30 September 2026). About half are chainsaws, pole saws or pruners (542). About a third are brushcutters, trimmers, hedge trimmers or edgers (347). Most of the rest are blowers, vacuums and sprayers (97) and power cutters (33).

Some of the entries it lists:

What the same finder doesn't show matters as much:

• It isn't a lawn mower plug in NGK's list. Of the 1,069 entries, one is a mower (a Flymo L300). NGK lists no BPMR7A for any Victa, Briggs & Stratton or Rover machine.
• Not every machine from one maker takes it. NGK lists a CMR6H, a different plug, for the Stihl BR600 and BG86 blowers.
• It isn't listed for marine, motorcycle or snowmobile engines in NGK Australia's finder.

NGK Australia says its equipment listings are "considered under normal conditions of use, fitted by a professional". Check your machine's owner's manual, or look it up in NGK Australia's online part finder (see Sources), before you buy.

How to read the BPMR7A number

NGK's part number chart decodes it like this:

1. B: 14 mm thread. A plain B plug has a 20.8 mm hex, but NGK lists B(P)M-A plugs as the exception with a 19 mm hex.
2. P: projected insulator. NGK says a projected plug sits further into the combustion chamber for better ignitability.
3. M: small spark plug. NGK's chart gives the B(P)M small type a 9.5 mm thread length.
4. R: resistor, which NGK says suppresses ignition noise.
5. 7: heat range. NGK's chart runs from hot (low numbers) to cold (high numbers).
6. A: part of the type code. NGK's chart groups it with the B(P)M-A size but gives it no separate meaning.

BPMR7A cross reference: Champion, Bosch, Denso and others

NGK Spark Plugs Australia's cross-reference matches these plugs to the BPMR7A:

Source: NGK Spark Plugs Australia cross-reference (ngk.com.au, and its crossref.pdf pp. 8 to 177), read 30 September 2026.

NGK calls its cross-reference "a guide only". Its lists don't always agree, either. NGK Australia matches the Bosch WSR6F to the BPMR6A, while NGK's European (2017/2018) and North American power-equipment charts match it to the BPMR7A. If your old plug's equivalent is on the edge, go by the machine's listing, not the cross-reference.

BPMR6A vs BPMR7A

They're the same size. Only the heat range differs: the BPMR6A is one step hotter. NGK's heat range page explains the risk of the wrong one:

• Too cold a plug runs too cool, so deposits build up on the firing end and it can lose its spark.
• Too hot a plug runs too hot and can cause pre-ignition, which NGK says can melt the electrodes and damage the piston.

So fit the heat range the machine calls for. In NGK Australia's commercial and industrial finder, the BPMR6A is the listed plug for 350 entries, and the BPMR7A for 1,069.

How to check which plug your machine takes

1. Look up the machine in its owner's manual or in NGK's part finder by make and model.
2. If your old plug is another brand, find its number in the cross-reference table above, then check the machine's listing.
3. Match the heat range: a BPMR6A and a BPMR7A are not interchangeable just because they screw in.
4. Before fitting, confirm the thread reach is right for the engine. That's step 1 of NGK's own installation instructions.
5. Set the gap your machine's manual gives. NGK supplies it at 0.7 mm; Stihl's MS 170/180 and Husqvarna's 372 XP manuals give 0.5 mm.

Which BES product fits

• Pick the 5 x NGK Spark Plugs BPMR7A if NGK or your manual lists a BPMR7A for one or two machines.
• Pick the 10 x NGK Spark Plugs BPMR7A if you run several machines on the same plug.
• Pick the 5 x NGK Spark Plugs BPMR6A or the 10 x NGK Spark Plugs BPMR6A if your machine lists the hotter BPMR6A.

All four are in ignition and electrical.

Questions people also ask

What is the gap on an NGK BPMR7A?

NGK gives 0.7 mm (0.028 in) as supplied. NGK Australia says the gap is set at the factory to suit its catalogue applications in most cases, but some need adjusting, so check your owner's manual: Stihl's MS 170/180 manual and Husqvarna's 372 XP manual both give 0.5 mm.

What thread size is a BPMR7A?

14 mm thread with 9.5 mm reach and a 19 mm hex (NGK's figures). Our listing gives a 1.25 mm thread pitch.

What is the Champion equivalent of an NGK BPMR7A?

NGK Australia lists the Champion RCJ6Y, RCJ7Y and 859. Bosch's is the WSR5F and Denso's is the W22MPR-U.

Does a Stihl chainsaw take a BPMR7A?

Many do. NGK Australia lists it for the Stihl MS170, MS180, MS250 and MS261, but not for every Stihl machine, so check the model.

Is there an iridium BPMR7A?

NGK Australia's part finder lists no iridium option for any BPMR7A entry. NGK's part number has no iridium (I or IX) or platinum letter after the heat range, and our listing gives a nickel centre electrode.

What's the difference between BPM7A and BPMR7A?

The R: the BPMR7A has a resistor and the BPM7A doesn't. NGK Australia offers the BPMR7A as the resistor option for 407 entries where the listed plug is a BPM7A.

Related reading

• Do I need a Kevlar mower belt?
• What size is a 1/2 x 95 mower belt?

Sources

• NGK Spark Plugs Australia, part finder, commercial and industrial, marine, motorcycle, ATV and snowmobile applications (ngk.com.au/partfinder), read 30 September 2026.
• NGK Spark Plugs Australia, spark plug cross-reference (ngk.com.au, and ngk.com.au/crossref.pdf), read 30 September 2026.
• NGK Spark Plugs Australia, technical information: Heat Range, Electrode Gap, Projection, Installation, Resistor Spark Plugs, and FAQ (ngk.com.au/technical_info, ngk.com.au/ngk/faq), read 30 September 2026.
• Niterra EMEA, NGK part finder entry for the BPMR7A (Husqvarna 371 XP page, ngkntk.com), read 30 September 2026.
• NGK Spark Plugs (North America), Spark Plug Cross Reference, power equipment (ngksparkplugs.com), p. 13, read 30 September 2026.
• STIHL, MS 170, 180 Instruction Manual (0458-207-8321-C, 2024), Specifications, PDF p. 36 (ssc.stihl.com), read 30 September 2026.
• Husqvarna, 365 Special, 372 XP, 372 XPG Operator's manual (30.11.2021), Technical data, PDF p. 34 (husqvarna.com), read 30 September 2026.
• Niterra EMEA, NGK Spark Plugs and Glow Plugs 2017/2018 catalogue, "How to read our part number" (PDF p. 4) and Bosch to NGK cross-reference (PDF p. 467) (ngkntk.com), read 30 September 2026.

Checked against NGK Spark Plugs Australia's part finder and cross-reference, NGK's European and North American catalogues, the Stihl and Husqvarna manuals and our own product data on 30 September 2026.