NGK Spark Plug - CR5HSB
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The NGK CR5HSB is a standard copper-core nickel spark plug used in select portable generators, small marine outboards, utility engines, and compact power equipment where the manufacturer specifies the CR5HSB / NGK 6535 plug profile. It is a compact 10 mm, short-reach spark plug designed for small-engine applications that require a flat-seat, resistor-style plug with a solid terminal.
This plug should be installed only where the engine service manual, equipment label, or factory application chart specifically calls for NGK CR5HSB, NGK 6535, or an approved equivalent.
Key Features
- Genuine NGK standard spark plug.
- NGK part number: CR5HSB.
- NGK stock number: 6535.
- Copper-core nickel construction for standard small-engine service.
- Resistor-style plug to help reduce ignition-related RFI noise.
- Compact short-reach design for select small engines and portable equipment.
- Thread diameter: 10 mm / M10 x 1.0.
- Thread reach: 12.7 mm / 1/2 in.
- Hex size: 16 mm / 5/8 in.
- Seat style: flat / gasket seat.
- Tip style: non-projected.
- Heat range: 5.
- Factory preset gap reference: 0.028 in. / 0.7 mm.
- Solid terminal configuration.
Application Compatibility
Common application context includes select small engines and equipment where the factory plug chart calls for NGK CR5HSB / 6535, including:
- Select Honda portable inverter generator applications where specified
- Select Honda small-engine applications using Honda plug references 98056-55757 or 98056-55777, where confirmed by engine model
- Select compact marine outboards and trolling outboard applications where the factory chart calls for CR5HSB
- Select utility engines, commercial compactors, trimmers, and small power equipment where specified
- Other small-engine applications requiring a 10 mm, 12.7 mm reach, gasket-seat plug with the correct heat range and terminal style
Use this spark plug only where the equipment manufacturer's application chart specifically lists CR5HSB, 6535, or an approved equivalent.
Fitment Notice
Confirm fitment by exact equipment brand, engine model, serial number, service manual, and factory spark plug chart before ordering. Small-engine spark plugs can look similar but differ in thread reach, heat range, seat style, terminal style, resistor specification, projection, and required gap. Installing the wrong plug can cause hard starting, misfire, poor idle, overheating, thread damage, piston contact, or ignition-system issues.
When This Part Needs Replacement
Replace spark plugs during scheduled tune-up service or whenever the plug is worn, fouled, fuel-soaked, oil-contaminated, corroded, cracked, damaged, or causing hard starting, rough idle, stalling, weak acceleration, poor low-speed running, or no-start conditions. Portable generators and small outboards should have spark plugs inspected regularly because low-load operation, old fuel, moisture, and seasonal storage can accelerate fouling.
Installation Notes
Check the plug number and required gap against the engine service chart before installation. Install into clean, undamaged cylinder head threads and tighten to the manufacturer's torque specification for the exact engine. Because this is a gasket-seat plug, confirm the sealing washer is present and seats properly. Avoid adding anti-seize unless the engine or spark plug manufacturer specifically calls for it, as lubricant can change clamping load and increase the risk of over-tightening in small aluminum cylinder heads.
Alternate/Superseded Part Numbers
- NGK CR5HSB — spark plug part number
- NGK 6535 — NGK stock number
- CR5HSB 6535 — common catalog reference
- Honda 98056-55757 — cross-reference; verify by engine model and plug chart
- Honda 98056-55777 — cross-reference; verify by engine model and plug chart
- Denso U16FSR-UB / U16FSRUB — cross-reference; verify by application
- Champion Z9Y — cross-reference; verify by application
- Torch A5RTC — aftermarket cross-reference; verify by application
Parts Desk Insight
The CR5HSB is a compact 10 mm spark plug commonly used in small engines where space, vibration, and low-load running are major factors. Match it by exact plug number, reach, heat range, and gap rather than by equipment category alone. For generators and small outboards, a fresh plug is often part of a proper seasonal service along with clean fuel, oil service, and air-filter inspection.
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.