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What the Koeep M10 Kit Covers

The Koeep M10 Round Rearview Mirror Kit for Honda Trail CT70/CT90/CT110/CT125 fits all four CT platforms: CT70 (1969–1994), CT90 (1966–1979), CT110 (1980–1986), and CT125 (2020–2026). Every stem runs an M10 × 1.25mm fine thread, the spec Honda used across the CT-series through the 2026 model year, and the pair ships with one right-hand and one left-hand stem, so no adapters are needed.

Compliance: the kit is engineered to the 2026 revision of FMVSS 111 (49 CFR §571.111) and SAE J268, with ECE R46 coverage. The 110mm round convex lens delivers a ≥78° horizontal field of view against the 60° Class III minimum for L3e/L5e motorcycles under ECE R46 2026. On the 2023–2026 CT125 with CAN-bus 3.0 the mirror is electrically passive, with zero bus-conflict risk and no resistor modules required.

Fitment Data Across the CT-Series

The table is the data backbone for all four bikes. Thread, Koeep stem material, torque, and salt spray rating are identical on every platform, so they are listed here once: M10 × 1.25mm (LH/RH), 6061-T6 aluminum, 18–22 N·m, and ISO 9227:2022 at 720 hours or more.

Materials: What Changed for 2026

Stem: forged 6061-T6 replaces zinc pot metal

Honda OE stems from the 1970s through the 1990s were zinc-pot-metal castings. The Koeep stem is cold-forged 6061-T6 aluminum per SAE AMS 4117 and ASTM B221: 42% less mass than an equivalent zinc casting, with yield strength up to 276 MPa. That margin matters when a loaded CT125 runs near its GVM on adventure tours.

Ball joint and glass

Traditional nylon 6/6 bushings let mirrors sag at sustained 100–110 km/h and in high heat. The interface here uses a PTFE-impregnated acetal (POM-C) socket instead, holding position at 85°C ambient per ISO 16750-4:2023. The glass is 1.8mm soda-lime, first-surface silvered under a SiO₂ overcoat, with ≤1.5% haze after 1,000 hours of QUV-B weathering (ASTM G154 Cycle 1).

Thread Direction: Check Before You Install

Honda has run a split-thread convention on the CT-series for decades. The left mirror mount takes a standard right-hand M10 thread, and the right-side mount on most CT models uses a left-hand (reverse) M10 × 1.25mm thread. The Koeep mirror pair ships with both orientations, labeled on the protective sleeve, so read the sleeve before you fit anything.

A right-hand mirror forced into the right perch feels tight at first, then wind-induced rotational precession backs it out within 10–15 km of riding. Genuine Honda reverse-thread stems carry a notch or groove near the base as the factory indicator.

Run a thread pitch gauge over both perches before installing. Stripped threads on 40-plus-year-old CT90s are common; a time-sert M10 × 1.25mm insert rebuilds them, and it holds up better in this spot than a wire-type Helicoil.

DTC Codes That Can Surface During Mirror Service

The mirror is a fully mechanical assembly with no embedded electronics, so it generates no codes of its own. On the 2023–2026 CT125 with CAN-bus 3.0, mirror work often means opening the front cowl or headlamp nacelle. If connectors get disturbed and the ignition is cycled, adjacent faults can log:

Troubleshooting: Three Common Failures

Mirror blur above 85 km/h on a 2024–2026 CT125

Cause: Honda's revised handlebar clamp (P/N 53105-KY2-901) trades rubber isolation for sharper steering feedback. It passes the 2nd-order engine vibration, the 6,500 to 7,200 RPM band of the 124.9cc single, straight into the mirror stems. The 6061-T6 stem is stiffer than OE steel, so at certain resonant frequencies it couples the vibration rather than damping it.

Fix: fit a 3mm EPDM isolation washer (70 Shore A) between the mirror base and the perch mount, then torque to 20 N·m. It compresses about 0.4mm and decouples the vibration without giving up clamp integrity. For stubborn cases, fill the hollow stem with 2-part expanding polyurethane foam (80 kg/m³ cured density) to shift the natural frequency above the engine's excitation range.

MIL on with DTC B1005 after installation

B1005 is a Body Control Module front-harness open-circuit code. On the 2023–2026 CT125, the turn-signal sub-harness routes through the same cowl cavity you open for mirror replacement. Cycle the ignition while a connector is out and the BCM runs a bulb check, sees an open circuit, and stores the code. Fast-flashing turn signals usually come with it.

Fix: reconnect every front turn-signal connector first. With HDS, clear the code under Body Electrical → BCM → Self-Test → Clear DTCs. Without HDS: battery negative off for 60 seconds, then three ignition ON/OFF cycles (ON 10 seconds, OFF 10 seconds, three times). If B1005 returns, inspect pin C7 (violet/yellow wire) at the BCM connector for corrosion, a known 2024–2026 weak point.

Sustained highway speed on tour

The assembly is validated to 120 km/h continuous per ISO 16750-3:2023, Test Group Vibration Profile 3. Standard nylon sockets lose clamping force above 70°C as heat loosens their grip on the aluminum ball stud; this POM-C design holds ≥85% of its initial clamping torque after 500 thermal cycles from -20°C to +85°C. On long routes such as the TAT or Pan-American Highway segments, re-check stem torque at the 500 km mark, in line with Honda's chassis-fastener service intervals.

Frequently Asked Questions