NGK 5666 spark plug for the 2011-2020 Honda NPS50 Ruckus 49cc and other vehicles ignites the fuel mixture in the combustion chamber. Among NGK spark plugs, the Standard line in the yellow box is engineered for OE applications.
- NGK Standard line plug with a nickel alloy center electrode for consistent performance
- Trivalent metal plating that resists corrosion and seizing for easier installation and removal
- High grade alumina silicate ceramic insulator for optimal dielectric performance
- Solid 98% pure copper core for heat dissipation, conductivity and ultra wide heat ranges
- Cold-rolled threads that help prevent cross-threading and damage to cylinder heads
- Triple gasket sealing against combustion gas leakage
Quick facts
- Part: NGK 5666 spark plug
- Fits: 2011-2020 Honda NPS50 Ruckus 49cc and other vehicles
- Condition: New
A worn plug can show up as hard starting, a misfire or a rough idle. Before you replace one, rule out a weak battery, a fuel supply problem or a faulty coil or plug cap, since each of those can also make an engine run rough.
Fits
This plug is listed for a wide range of Honda models, including the 2012-2017 Honda CRF150R Expert 149cc and the 2012-2019 Honda CRF150R 149cc. It is best for engines with OE nickel alloy plugs and is not recommended where the factory plug is precious metal. If your Honda is not named here, look it up by year and engine in the "Vehicles it fits" section.
Specifications
Fit and size
- Thread size: M10 - 1.0
- Quantity per vehicle: 1 on most listed models, 4 on some
Build and materials
- Metallurgy: copper
- Center electrode: nickel alloy
- Gasket seat: crush
- Gap style: J-Gap
- NGK service number: CR8EH-9
- Condition: New
In the box
One spark plug. The number each vehicle needs varies by model: most listed models take one plug and some take four.
Interchange: 98059-58916 · CR8EH-9
RGU94C · 4127 · U24FER9 · B8RH
Product information is for general reference and may contain errors. See our Disclaimer.
This part cross-references / interchanges with the following part numbers:
RGU94C, 4127, U24FER9, 98059-58916, 9805958916, 5666, CR8EH-9, B8RH
Frequently Asked Questions
Is NGK 5666 the right CRF150R spark plug for a 2012-2019 Honda CRF150R 149cc?
Yes. NGK 5666 is listed for the 2012-2019 Honda CRF150R 149cc and for the 2012-2017 Honda CRF150R Expert 149cc.
What thread size does the NGK 5666 spark plug have?
NGK 5666 has an M10 - 1.0 thread and a crush gasket seat.
Is this Standard spark plug a copper or a precious-metal plug?
This plug has a solid 98% pure copper core and a nickel alloy center electrode, not a precious-metal tip. It is not recommended on engines with factory precious metal plugs.
Does NGK 5666 replace the CR8EH-9 plug?
Yes. CR8EH-9 is the NGK service number for this plug, and 5666 is its stock number, so both names point to the same spark plug.
How can I tell if my NGK 5666 spark plug is worn?
With the engine off and cool, look for a worn-down electrode, a cracked insulator or heavy deposits. Hard starting, misfires or a rough idle can also point to a worn plug.
