Spark Plug Boot (Angled) | Honda CB450 / CL450 / CB500T

Description

Angled Spark Plug Boot | Honda CB450 / CL450 / CB500T

Intermittent ignition problems on Honda twins are often blamed on the coils, but the connection between the plug wire and boot is usually the real cause. This angled spark plug boot restores a reliable, water-resistant seal from your coil to the spark plug.

Why You Need This

Over time, the original boots degrade, crack, and lose their seal — letting moisture in and electrons out. This replacement boot has stock appearance and features a water-resistant seal. The angled design is specific to the CB450, CL450, and CB500T — the cylinder head fins on Honda’s vertical twin require a bent boot to clear properly. A straight boot can physically fit but sits snug against the fins. If you are working on a CB350, CL350, or CB360, you need the straight spark plug boot instead.

Specifications

Replaces OEM	30700-890-013, 30700-292-000, 30700-890-000, 30700-890-003
Fits Models	CB450 K0–K7 (1965–1974), CL450 K0–K6 (1967–1974), CB500T (1975–1976)
Qty	Sold Individually — Two Needed Per Bike

Installation

Difficulty: Beginner

1. Trim away about 1/4″ of old wire from the end of the plug wire to expose fresh copper.
2. Screw the boot onto the wire end — press and turn clockwise until roughly 1/2″ of wire is seated inside the boot.
3. Remove the terminal nut from the top of the spark plug to expose the threaded stud.
4. Press the boot firmly onto the spark plug stud.

If the boot does not seat on the plug: The spark plug has a removable terminal nut threaded onto the top electrode. Unscrew and remove it to expose the stud. See our terminal nut vs. terminal stud article for details.

Frequently Asked Questions

What is the difference between this boot and SKU 3009?

This boot (3039) is angled to clear the cylinder head fins on the CB450/CL450/CB500T vertical twin. SKU 3009 is a straight boot designed for the CB350, CL350, CB360, and similar models where the plug sits in a more accessible position.

How many do I need?

Two — one per cylinder. The CB450, CL450, and CB500T are twin-cylinder engines.

My boot does not fit onto the spark plug. What is wrong?

The spark plug has a removable terminal nut threaded onto the top electrode. Unscrew and remove the terminal nut to expose the threaded stud, then press the boot on. See our terminal nut article for details.

Should I replace the plug wire too?

If the wire is cracked, brittle, or measures high resistance, yes. Trimming 1/4″ of old wire before installing the new boot gives you a fresh connection point.

You Might Also Need

• NGK BR8ES Spark Plug — the correct plug for all CB450, CL450, and CB500T engines
• Ignition Coil — if the boot swap doesn’t fix your spark issue, the coil may be next

Last updated: March 2026