NGK BR8ES Spark Plug | Honda CB350, CB360, CB450, CB500T
The correct copper core spark plug for every Honda CB350, CB360, CB450, and CB500T twin. NGK BR8ES — the current-production replacement for the original B8ES — with a built-in resistor to reduce electromagnetic interference. Sold individually; you need two per bike.
Why You Need This
Old spark plugs foul, gap out, and misfire. If your bike is hard to start, misfires under load, or runs rough at idle, worn plugs are the first thing to check. These are also the go-to plug for reading carburetor jetting — fresh plugs give you a clean porcelain insulator to read mixture color after a plug chop.
NGK transitioned from the B8ES to the BR8ES in January 2020. The “R” designates a built-in resistor that reduces electromagnetic interference — better for modern devices like phones, GPS, and radios. Performance is identical to the original B8ES for these engines.
Specifications
| Spec | Detail |
|---|
| OEM Part Numbers | 98079-58840, 98079-58810, 98079-58840-S, 98079-58860 |
| Fits Models | CB350 (1968–1973), CL350 (1968–1973), SL350 (1969–1973), CB360 (1974–1976), CL360 (1974–1975), CJ360 (1976–1977), CB450 (1965–1974), CL450 (1967–1974), CB500T (1975–1976) |
| NGK Part Number | BR8ES (replaces discontinued B8ES) |
| Type | Copper core, resistor plug |
| Gap | .030" |
| Sold As | Each (2 required per bike) |
Note: Sold individually — you need TWO spark plugs per bike.
Installation
Difficulty: Beginner
Tools needed: Spark plug socket (13/16"), gap gauge
- Unscrew the terminal nut from the top of the new plug to expose the threaded terminal stud — Honda spark plug boots thread onto the stud, not the nut
- Set the electrode gap to .030" using a gap gauge
- Apply a light coat of oil to the plug threads
- Thread the plug in by hand to avoid cross-threading, then snug with a spark plug socket
Terminal nut tip: The removable nut on top of the plug confuses a lot of people — it looks like it’s part of the plug, but it unscrews. Honda plug boots use the threaded stud underneath, not the nut. See our guide on terminal nut vs. terminal stud for a visual walkthrough.
Our ignition troubleshooting video covers spark plug testing as part of a full ignition system diagnostic — useful if you’re chasing a misfire or weak spark.
Frequently Asked Questions
What's the difference between the B8ES and BR8ES?
The BR8ES replaced the B8ES in January 2020. The “R” means it has a built-in resistor to reduce electromagnetic interference — better for phones, GPS, and radios. Performance is identical for these vintage Honda engines. If you see B8ES listed in an old manual, the BR8ES is the current direct replacement.
Why won't my spark plug boot fit on the new plug?
You need to unscrew the terminal nut from the top of the plug. Honda spark plug boots thread onto the smaller stud underneath — not the removable nut. This is the most common question we get about this plug. See our terminal nut guide for step-by-step photos.
How many spark plugs do I need?
Two — one per cylinder. All the Honda twins (CB350, CB360, CB450, CB500T) have two cylinders. These are sold individually, so add two to your cart.
What gap should I use?
.030" for all models. Check the gap on every new plug before installing — they’re sometimes off from the factory.
What else should I check while I'm doing a tune-up?
Spark plugs are usually replaced alongside other ignition parts. If your ignition coils produce weak or yellow spark instead of bright blue, replace them. Check your condenser — a failing condenser burns through points quickly and causes high-RPM cutout. And inspect your spark plug boots (or angled boots for the CB450/CB500T) — cracked or loose boots cause intermittent misfires that mimic bad coils.
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Last updated: February 2026
