Mini Bike Spark Plug Chart
The factory NGK plug and gap for every Honda, Kawasaki, Yamaha and import mini bike engine we sell parts for, and the one range cooler plug to run after a bore kit. Twenty four models, one chart.
Spark Plug
By Model
Twenty four models
Every plug we spec
OEM plug is the factory NGK part number. Gap is 0.6 to 0.7mm across the board. The cooler plug is the one range up TBparts recommends for a bore kit, a race head or sustained high speed use. Linked plugs are in stock.
- Factory NGK plug for 24 models
- 0.6 to 0.7mm gap on every one
- One range cooler plug for bore kits
- Every part number verified against NGK
One plug covers most of the chart: TBparts lists the NGK CR7HSA as a great choice for any bike originally equipped with a CR7HSA, CR6HSA, C7HSA or C6HSA. That is most Honda 50/70 engines, pit bikes based on the Honda 50/70, the KLX110, KLX140 and TTR110.
| Make | Model and years | OEM plug | Gap | One range cooler |
|---|---|---|---|---|
| Honda | Z50A K0 to K6, 1968 to 1978 | C6HSA | 0.6 to 0.7mm | C7HSA |
| Honda | Z50R 1979 to 1981 | C6HSA | 0.6 to 0.7mm | C7HSA |
| Honda | Z50R 1982 to 1999 | CR6HSA | 0.6 to 0.7mm | CR7HSA |
| Honda | XR50 and CRF50, 2000 and up | CR6HSA | 0.6 to 0.7mm | CR7HSA |
| Honda | CT70 and CT70H, 1969 to 1982 and 1991 to 1994 | C7HSA | 0.6 to 0.7mm | CR8HSA |
| Honda | TRX90, 1993 and up | CR7HSA | 0.6 to 0.7mm | CR8HSA |
| Honda | ATC70, TRX70, SL70, XL70 | C6HSA | 0.6 to 0.7mm | C7HSA |
| Honda | CRF110 | CPR6EA-9S | 0.6 to 0.7mm | CPR7EA-9S |
| Honda | Grom 125 and MSX125, 2014 to 2020 | CPR6EA-9 | 0.6 to 0.7mm | CPR7EA-9 |
| Honda | Grom 125 and MSX125, 2022 and up | CPR7EA-9S | 0.6 to 0.7mm | CPR8EA-9 |
| Honda | Monkey 125, 2018 to 2021 | CPR6EA-9 | 0.6 to 0.7mm | CPR7EA-9 |
| Honda | Monkey 125, 2022 and up | CPR7EA-9S | 0.6 to 0.7mm | CPR8EA-9 |
| Honda | CRF125 | CPR6EA-9 | 0.6 to 0.7mm | CPR7EA-9 |
| Honda | XR100 and CRF100 | CR7HSA | 0.6 to 0.7mm | CR8HSA |
| Honda | CRF150F, 2003 to 2005 | DPR8EA-9 | 0.6 to 0.7mm | DPR9EA-9 |
| Honda | CRF150F, 2006 to 2017 | CPR8EA-9 | 0.6 to 0.7mm | CPR9EA-9 |
| Kawasaki | KLX110 and KLX110L | CR6HSA | 0.6 to 0.7mm | CR7HSA |
| Kawasaki | KLX140 and KLX140L | CR7HSA | 0.6 to 0.7mm | CR8HSA |
| Kawasaki | Z125 Pro | CR6HSA | 0.6 to 0.7mm | CR7HSA |
| Yamaha | TTR110 | CR6HSA | 0.6 to 0.7mm | CR7HSA |
| Import | Daytona 190 4 valve | ER9EH or ER9EHIX | 0.6 to 0.7mm | n/a, already a cold plug |
| Import | Lifan 125cc, 54 x 54mm | CR6HSA | 0.6 to 0.7mm | CR7HSA |
| Import | Lifan 50, 70 and 110cc | CR6HSA | 0.6 to 0.7mm | CR7HSA |
| Import | YX125 and YX140 | CR6HSA | 0.6 to 0.7mm | CR7HSA |
How Heat
Ranges Work
Hotter or cooler
The number runs backwards
The number in an NGK part number is the heat range, and a higher number is a cooler plug. A cooler plug pulls heat out of the combustion chamber faster, which is exactly what a big bore kit or a race head needs.
- Go one range cooler for a bore kit, race head or sustained high speed use. It combats hotter running temperatures and heads off overheating.
- Go one range hotter on a stock engine that runs at constant low speed or in cold weather, so the plug stays clean and the engine runs smooth.
- CR6HSA becomes CR7HSA. CPR6EA-9 becomes CPR7EA-9. Same plug, one digit up.
NGK heat range scale
What The Color
Tells You
Read the plug
Wrong. Act on these.
- White or light gray insulator. Lean, or the plug is too hot. Jet up first; if it persists on a modified engine, go one range cooler.
- Black, dry and sooty. Rich mixture or a plug that is too cold. Check filter oiling, then jet down.
- Black and wet. Oil fouling. Worn rings or valve seals, or the engine is not getting warm enough.
- Blistered or melted electrode. Severe overheating. Stop riding it. Lean jetting, wrong heat range, or timing.
Right. Leave it alone.
- Light brown or tan insulator. Mixture and heat range are correct.
- Sharp, square electrode edges. Not rounded off. The plug is not worn out.
- Gap still at 0.6 to 0.7mm. Check it with a feeler gauge every time the plug is out.
- No deposits on the threads. The seal is holding.
A spark plug is the cheapest diagnostic tool on the bike. Pull it after a hard run and the insulator tells you whether the jetting and the heat range are right. See the carburetor and jetting guide for what to change.
Four Things
That Get Skipped
Fitting a plug
Gap it before it goes in
New plugs are not always gapped for your engine. Set 0.6 to 0.7mm with a feeler gauge, bending only the ground electrode.
Start by hand, then torque it
Aluminum heads cross thread easily, so run the plug in by hand until it seats. NGK's spec for the 10mm plugs in this chart is 7.2 to 8.7 ft lb in an aluminum head; the 8mm ER9EHIX is 5.8 to 7.2. Without a torque wrench, a new plug with a fresh crush washer is about a half turn past finger tight, and a reused plug only about a twelfth of a turn.
Match the cap to the plug
The R in CR7HSA means resistor. Older 1969 to 1980 Honda 50 and 70 engines ran non resistor plugs and caps; TBparts sells a non resistor cap for those bikes.
Iridium on the Daytona 190
The four valve Daytona 190 takes an ER9EH, and the ER9EHIX Iridium IX version (NGK stock number 96652) lasts longer and fires cleaner under load. Not needed on stock 50/70 engines.
NGK Plugs
And Caps
In stock
ResistorBore kit plugMost popular
NGK CR7HSA
One range cooler than the CR6HSA. Fits most Honda 50/70 engines, pit bikes based on the Honda 50/70, the KLX110, KLX140 and TTR110. Replaces CR6HSA, C7HSA and C6HSA.
$3.99
ResistorOEM spec
NGK CR6HSA
The factory plug for Z50R 1982 and up, XR50, CRF50, KLX110, Z125, TTR110, Lifan and YX engines.
$4.49
Non resistorCT70 stock
NGK C7HSA
Factory plug for the CT70 and CT70H. Non resistor, for the older 50 and 70 engines.
$4.49
Non resistorVintage stock
NGK C6HSA
Factory plug for the Z50A K0 to K6, Z50R 1979 to 1981, ATC70, TRX70, SL70 and XL70.
$4.49
ResistorCRF110 / Grom
NGK CPR6EA-9
Fits the CRF110 and CRF125. The factory plug for the CRF125, Grom and Monkey 2014 to 2021.
$8.99
IridiumDaytona 190
NGK Iridium IX ER9EHIX
For the Daytona 190 four valve and other high output import engines. Fine wire iridium center electrode for quicker starts and a cleaner spark under load.
$25.99
Spark Plug
Questions
Get some answers
What spark plug does a KLX110 take?
The factory plug is an NGK CR6HSA gapped at 0.6 to 0.7mm. With a bore kit or a race head, TBparts recommends going one range cooler to a CR7HSA.
What spark plug does a CRF110 take?
An NGK CPR6EA-9S from the factory, gapped 0.6 to 0.7mm. For a bore kit, the one range cooler plug is a CPR7EA-9S.
What spark plug does a Z50 take?
It depends on the year. Z50A K0 through K6 (1968 to 1978) and Z50R 1979 to 1981 use a C6HSA. Z50R 1982 to 1999 uses a CR6HSA. All are gapped 0.6 to 0.7mm.
What spark plug does a CT70 take?
Every CT70 and CT70H, 1969 to 1982 and the 1991 to 1994 revival, uses an NGK C7HSA gapped at 0.6 to 0.7mm.
Is a higher NGK number hotter or colder?
Colder. NGK heat range numbers run backwards from what most people expect. A CR7HSA is one range cooler than a CR6HSA, and a CR8HSA is cooler still.
When should I run a cooler plug?
After a big bore kit, a race head, or any time the engine runs sustained high speed. A cooler plug pulls heat out of the chamber faster and helps avoid overheating. Go one range at a time.
Can I use a CR7HSA in place of a C6HSA?
Yes. TBparts lists the CR7HSA as a good choice for any bike that originally took a CR7HSA, CR6HSA, C7HSA or C6HSA. The R means resistor, which is fine on these engines, and the 7 is one range cooler.
What gap should I run?
0.6 to 0.7mm, which is 0.024 to 0.028 inch, on every plug in this chart. Check it with a feeler gauge before installing, and bend only the ground electrode to adjust.
TBparts Tech Center
