LED Light Bulb Upgrade Kit | Honda CB175 / CB200 / CB350 / CB450 / CB500K
The stock incandescent bulbs in your turn signals, tail light, and gauge cluster have been taxing your charging system for fifty years. Some of them are getting hard to find. This kit swaps all of them for LEDs in one go — including the flasher relay and indicator diode you'll need to make it all work.
Why You Need This
Modernizing the lights on a vintage Honda isn't just a brightness upgrade. Every incandescent bulb you replace reduces load on a charging system that's already running at the edge. Your battery stays topped up longer, your stator runs cooler, and your lights stay visible even at idle.
Converting to LED isn't plug-and-play on these bikes. Three problems need solving: the thermal flasher won't fire reliably because LEDs don't draw enough current, the single turn signal indicator bulb in your gauge cluster gets its ground through the opposite turn signal (which doesn't work with LEDs), and the bulbs themselves are polarity-sensitive. This kit includes the low-threshold electronic flasher and the diode harness that solve all three.
Pair this with our voltage regulator/rectifier kit for the biggest electrical upgrade you can do on these bikes.
Specifications
| Spec | Detail |
|---|
| Fits Models | CB175 K0–K7 (1968–1973), CL175 K0–K7 (1968–1973), SL175 K0/K1/K2 (1970–1972), CB200/CL200 (1973–1976), CB350 K0–K5 (1968–1973), CL350 K0–K5 (1968–1973), SL350 K0–K2 (1969–1973), CB450 K0–K7 (1965–1974), CL450 K0–K6 (1967–1974), CB500K0/K1/K2 (1971–1973) |
| Voltage | 12V only |
| Kit Quantity | Sold as complete kit |
Important Notes
Factory sockets only. The LED bulbs are designed to drop into original Honda turn signal housings, tail light sockets, and gauge cluster sockets. They may not fit aftermarket or universal replacement housings. Check your existing bulbs and sockets before ordering if your bike has non-factory turn signals.
12V systems only. This kit does not fit 6V vintage Hondas.
What's in the Kit
- LED Gauge / Instrument Bulbs (x7)
- LED Turn Signal Bulbs (x4)
- LED Tail Light Bulb (x1)
- Low-Threshold Electronic Flasher Relay (x1)
- LED Turn Signal Indicator Diode Harness (x1)
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 new LEDs.
- Replace the turn signal, tail light, and gauge cluster bulbs with the LED replacements. 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.
- Install the diode harness. Connect the red wires of the diode to the light blue (right) and orange (left) turn signal wires in the headlight bucket. Connect the blue wire to the "positive" side of the gauge indicator bulb socket (the wire that touches the bulb's center pin). The other gauge bulb wire goes to ground — any solid dark green wire works.
- 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.
Why the diode is needed: On a bike with a single turn signal indicator bulb, the factory circuit completes the indicator's ground path through the opposite side's unlit turn signal. LEDs block that reverse flow because they only conduct in one direction. The diode restores the ground path so the indicator flashes with either side.
Full install walkthrough with on-bench demo of the ground path and polarity swap.
Frequently Asked Questions
Will this kit fit my 1972 CB350?
Yes. The CB350 K0 through K5 (1968–1973) is on the fitment list, including CL350 and SL350 variants. The kit uses the same gauge cluster bulb count and SAE turn signal sizes across all supported models.
Do I need to replace my flasher relay even if my turn signals work fine now?
Yes. The stock Honda thermal flasher works by heating a bimetallic strip with the current draw from the bulbs. LEDs draw a small fraction of that current, so the stock flasher either won't click at all or will hyperflash. The included electronic flasher solves this.
My 1971 CB175 has aftermarket turn signals. Will the LED bulbs fit?
Possibly, but we can't guarantee it. The kit's LED turn signal bulbs use standard SAE 1156 and SAE 1157 sockets matching the Honda factory housings. Many aftermarket turn signals use the same sockets, but some universal housings have non-standard wiring or a different bulb cavity. Check your existing bulb and socket before ordering.
My turn signals hyperflash at idle but are normal at higher RPM. Is the kit defective?
No. This is almost always a charging system issue — typically a weak battery or a tired regulator/rectifier. The electronic flasher needs a stable 12V supply to maintain its flash rate. When charging voltage sags at idle, the flasher speeds up. The fix is usually a fresh battery or a modern regulator/rectifier upgrade.
Can I install just the gauge bulbs or just the turn signals from this kit?
Yes, but the flasher and diode are only needed if any of your turn signal positions are LED. If you're just upgrading the gauge bulbs, you may not need the diode — we sell the LED instrument gauge bulbs separately in a 5-pack.
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Last updated: April 2026
