LED Light Bulb Upgrade Kit | Honda CB500T / CB550K / CB550F / CB750
The factory incandescent bulbs in your CB500T, CB550, or CB750 are drawing more current than they should, and some of the originals are getting hard to find. This kit swaps all fifteen bulbs for LEDs in one purchase — plus the electronic flasher relay and the diode needed to make the single-indicator gauge clusters work.
Why You Need This
Your vintage Honda's charging system was sized for stock incandescent bulbs forty or fifty years ago. Swapping to LEDs drops load on the stator and gives the battery room to stay fully charged — especially useful on bikes that sit idle for weeks between rides.
LED conversion on these bikes isn't just a bulb swap. The factory thermal flasher won't fire with LED-level current draw. If your gauge cluster has a single turn signal indicator bulb (most pre-1977 CB550K and all early CB750), the LED indicator needs a diode to restore its ground path. And LEDs are polarity-sensitive. This kit includes the electronic flasher and the diode harness, and the kit contents cover both single-indicator and dual-indicator gauge clusters.
Specifications
| Spec | Detail |
|---|
| Fits Models | CB500T (1975–1976), CB550K0 (1974), CB550K1 (1975), CB550K (1976–1978), CB550F (1975–1977), CB750 K0–K8 (1969–1978), CB750 F0–F3 (1975–1978), CB750A (1976–1978) |
| Voltage | 12V only |
| Kit Quantity | Sold as complete kit |
Important Notes
CB750 K0–K2 Owners (1969–1971): Contact us before ordering. The earliest CB750 K0, K1, and K2 models used single-filament front turn signal bulbs rather than the dual-filament bulbs used on all later CB550 and CB750 models. If you have a K0–K2 bike, reach out first so we can ship the correct bulb configuration. Ordering without contacting us often means receiving the wrong front bulbs.
Dual-Indicator Gauge Cluster Owners: You Don't Need the Diode. Some CB550F and CB750 models use separate left and right turn signal indicator bulbs (the 1977 CB550F is a common example). If your cluster has two distinct indicators, you do not need — and will not use — the diode harness included in this kit. Install only the LED bulbs and the electronic flasher. The kit still ships with the diode because most bikes in the lineup use a single indicator.
Factory sockets only. The LED bulbs are designed for the original Honda turn signal housings, tail light socket, and gauge cluster sockets. Aftermarket or universal housings may not fit.
Model-Specific Notes
- CB500T (1975–1976): This is a DOHC parallel twin, not a four. The LED kit bulbs work the same, but the reg/rec that pairs with this bike is the twin-family unit (see "You Might Also Need" below).
- CB550K / CB550F / CB750: These four-cylinder bikes use a different regulator/rectifier than the CB500T twin. See the four-family unit in "You Might Also Need."
- CB750 K0–K2: Single-filament front turn signals — contact us before ordering.
- CB550F / CB750 with dual L/R indicators: Skip the diode during install.
What's in the Kit
- LED Gauge / Instrument Bulbs (x9) — covers the deluxe cluster's 7 standard indicators plus the extra turn signal indicator and oil pressure light
- LED Turn Signal Bulbs (x4)
- LED Tail Light Bulb (x1)
- Low-Threshold Electronic Flasher Relay (x1)
- LED Turn Signal Indicator Diode Harness (x1) — only used on single-indicator clusters
The kit includes 9 gauge bulbs because the CB500T, CB550, and CB750 all use what Honda called the "deluxe" gauge cluster — two more indicator positions than the standard twin cluster on earlier bikes.
Installation
Difficulty: Intermediate
Tools needed: Phillips/JIS screwdriver, wire cutters, multimeter (helpful for troubleshooting)
- Clean all bulb sockets and connectors to remove corrosion before installing the new LEDs.
- Replace the turn signal bulbs, tail light bulb, and all 9 gauge cluster bulbs. If a gauge bulb doesn't light, swap the two socket wires — LEDs are polarity-sensitive.
- Replace the stock thermal flasher relay with the included electronic flasher.
- Single-indicator clusters only: Install the diode harness. Connect the red wires to the light blue (right) and orange (left) turn signal wires in the headlight bucket. The blue wire goes to the "positive" side of the gauge indicator socket (the wire that touches the bulb's center pin). The other socket wire goes to ground (any solid dark green wire).
- Dual-indicator clusters: Do not install the diode. Each indicator bulb is wired directly to its side's turn signal circuit.
- Test both turn signal directions. If the indicator bulb doesn't flash on a single-indicator cluster, swap the two wires at the gauge bulb socket and retest.
Full install walkthrough with a bench demo of how the gauge indicator ground path works and the polarity swap.
Frequently Asked Questions
Do I need the diode if my 1977 CB550F has separate left and right turn signal indicators?
No. The diode is only needed for single-indicator gauge clusters. If your cluster has two distinct indicators (one labeled L, one R, or two separate bulbs), each is already wired directly to its side's turn signal circuit. Install the LED bulbs and the flasher, but skip the diode harness.
My 1971 CB750 K1 — will the kit work?
Yes, with one step before ordering. CB750 K0, K1, and K2 use single-filament front turn signal bulbs rather than the dual-filament bulbs on later CB550 and CB750 models. Contact us before placing your order so we can configure the kit with the correct front bulbs.
Why does the kit include 9 gauge bulbs instead of 7?
The CB500T, CB550, and CB750 use Honda's "deluxe" gauge cluster, which has two more indicator positions than the standard twin cluster on smaller Hondas. The extra positions are typically an additional turn signal indicator and an oil pressure warning light. The 9 bulbs in the kit cover all positions.
Will the LED bulbs match my amber lens colors?
The turn signal LED bulbs are white; the amber color on your turn signals comes from the lens itself, the same way it did with the factory incandescent bulbs. The tail light LED is red to match the stop/tail lens.
My turn signals hyperflash at idle but work fine at higher RPM. Is the kit defective?
Almost always a charging-system issue, not a kit problem. The electronic flasher needs stable 12V to maintain its flash rate. When charging voltage sags at idle (weak battery, tired regulator/rectifier, or dirty grounds), the flasher speeds up. A fresh battery or the correct regulator/rectifier upgrade usually solves it.
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Last updated: April 2026
