Heat range is not a performance rating

The best motorcycle spark plugs for 2026

A spark plug is specified by the engine and not chosen by the rider, and that sentence saves more money than any comparison. The cross-reference is the specification: thread diameter, thread reach, seat type, and the code the engine manufacturer calls for. A plug with the right thread and the wrong reach will screw in and will put its electrode in the wrong place. The number in the middle of a plug code is its heat range, and it is the figure most often misread on this shelf. It describes how quickly the plug conducts heat away from its tip — not how hot the spark is, and not how much power the engine makes. A colder plug than specified fouls at low load; a hotter one runs hot under sustained load. It is a match to an engine, decided by that engine's maker, and this site reports the range as published rather than recommending a change. What the rider does choose is the electrode material. Copper cores conduct well and wear fastest, and are the cheapest. Platinum and iridium have finer centre electrodes that erode more slowly, which is why they carry longer published service intervals — a real, published difference in replacement frequency, and the one honest reason to spend more. Two last published lines matter at fitting. The gap, and whether the plug arrives pre-set: a fine-wire iridium plug has a fragile electrode that must not be bent to adjust, and makers say so. And the resistor, present or absent, which is not an upgrade but a match to the ignition system. We compare published cross-reference, heat range, electrode material, published service interval, gap and pre-set status, and resistor type.

These parts compared, figure by figure

1. 

   NGK BR8HSA

   A single NGK Yellow Box standard spark plug, reference BR8HSA, published as original-equipment quality with vehicle-specific fitment.

   Reference

   BR8HSA (from the title) — in NGK’s code, R denotes a resistor type and the digit is the heat range

   Range

   Yellow Box, NGK’s standard range (maker’s bullet)

   Fitment

   Vehicle-specific (maker’s bullet)

   Quality

   Stated original-equipment quality (maker’s bullet)

   Quantity

   1 plug (from the title)

   Thread size and reach

   Not published in this listing.

   Amazon reference

   DE B000CSGXDI · US B005Z09IJY · GB B004NMN0MG · FR B005Z09IJY · IT B005Z09IJY · ES B005Z09IJY

   EAN

   0087295155394

   • A named reference from a maker whose code system is documented and cross-referenced everywhere
   • Standard-range plug, which is what most manuals actually specify
   • Four bullets, none of which carries a dimension

   Best for: A machine whose manual names BR8HSA, or a cross-reference that arrives at it.

   ≈ €5

   Check price on Amazon
2. 

   NGK B7HS

   A single NGK Yellow Box standard spark plug, reference B7HS, with cold-rolled corrosion-resistant threads stated for heat dissipation — no resistor in the code.

   Reference

   B7HS (from the title) — no R in the code, and the digit is the heat range

   Range

   Yellow Box, NGK’s standard range following original equipment (maker’s bullet)

   Threads

   Cold-rolled with a corrosion-resistant coating, stated to dissipate heat well (maker’s bullet)

   Operation

   Stated to run smoothly at low and high engine speeds (maker’s bullet)

   Maker’s instruction

   Follow the fitting instructions (maker’s bullet)

   Quantity

   1 plug (maker’s bullet)

   Amazon reference

   DE B0000AXR66 · US B006B7FQIM · GB B006B7FQIM · FR B006B7FQIM · IT B0000AXR66 · ES B006B7FQIM

   EAN

   0087295151105

   • Publishes the thread treatment, which is what stops a plug seizing in an alloy head
   • The clearest contrast in this family: same maker, no resistor, one heat range apart
   • Not a resistor plug — that is a specification, not a saving

   Best for: A machine whose manual names B7HS — and not a substitute for one that names BR8HSA.

   ≈ €3

   Check price on Amazon
3. 

   NGK CR6HSA

   A single NGK spark plug, reference CR6HSA, whose listing consists of three bullets: original-equipment quality, the brand name, and the reference.

   Reference

   CR6HSA (from the title)

   Code

   C series rather than B; R denotes a resistor; 6 is the heat range

   Quality

   Stated original-equipment quality (maker’s bullet)

   Listing bullets

   Three: "original-equipment quality", "NGK", "CR6HSA".

   Thread size

   Not published in this listing — the Vnuipofa plug in this family publishes M10 for its own C-series reference.

   Gap

   Not published in this listing.

   Amazon reference

   DE B000CSIRHI · US B000CSIRHI · GB B000CSIRHI · FR B0025QX6IU · IT B0077PXDZK · ES B0025QX6IU

   EAN

   0087295129838

   • Published on all six marketplaces at a low price
   • A reference that cross-references cleanly against any manual
   • Three bullets, one of which is the brand name and one of which is the reference already in the title

   Best for: A small-capacity machine whose manual names CR6HSA.

   ≈ $7 / £7 / €5

   Check price on Amazon
4. 

   Vnuipofa CR7HSA

   A pack of two CR7HSA spark plugs for air-cooled four-stroke GY6 139QMB and QMA engines from 50 to 125 cc, with the thread published as M10 and the reach as 12.7 mm.

   Reference

   CR7HSA (from the title)

   Thread

   M10, stated 10 mm (maker’s bullet)

   Reach

   12.7 mm thread length (maker’s bullet)

   Stated engines

   Air-cooled four-stroke GY6 139QMB and QMA, 50–125 cc (from the title)

   Quantity

   2 plugs (from the title)

   Fitting

   Stated to need no special tool (maker’s bullet)

   Amazon reference

   B0GJ3CW8YK (one reference across 1 Amazon marketplace)

   • The ONLY spark plug in this family that publishes a thread size and a reach
   • Names the engine family — GY6 139QMB and QMA — rather than a marque list
   • Listed on the German market only at the time of collection

   Best for: A GY6-engined scooter or small machine, where two plugs at once is the sensible order.

   ≈ €8

   Check price on Amazon
5. 

   VooGenzek A7TC

   A single A7TC replacement spark plug in ceramic and metal for GY6 engines from 50 to 150 cc, scooters, ATVs and pit bikes, with a maker’s instruction to verify the model first.

   Reference

   A7TC (from the title)

   Materials

   Ceramic and metal, stated high-temperature resistant and durable (maker’s bullet)

   Stated engines

   GY6 50, 70, 90, 100, 110, 125 and 150 cc; moped scooters, ATVs, quads, dirt bikes, go-karts (maker’s bullet)

   Design note

   The maker states a large gap between tip and body reduces fouling and misfire risk (maker’s bullet)

   Maker’s instruction

   Verify the model number and size before ordering (maker’s bullet)

   Thread size

   The maker puts nothing in writing on this.

   Amazon reference

   B0DYY9J3LW (one reference across 1 Amazon marketplace)

   • Publishes a design rationale rather than only a claim — the gap between tip and body
   • Names seven engine capacities individually
   • No thread size or reach published, where another plug in this family gives both

   Best for: A GY6-engined machine whose plug is already an A7TC.

   ≈ €5

   Check price on Amazon