Dedicated Subsystem WorkbenchPlatform Gen: 2014–2026

2023 Honda Grom (MSX125) Throttle Body Synchronization & Fuel Delivery

Multi-cylinder vacuum sync specs, idle speed, EFI high-pressure fuel rail PSI, and injector resistance multimeter bench for 2023 Honda Grom (MSX125).

Gen 2014–2026

Factory Platform Compatibility: All workshop fluid capacities, maintenance milestones, torque specifications, and consumables on this specification sheet are factory-identical across model years 2014 through 2026.

Select Model Year:(Active: 2023)

2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026

Engine

124cc

Drive

420

Cooling

Air-Cooled

FSM Induction CalibrationSingle Cylinder (1 Throttle Bore)

Fuel Delivery, Throttle Body Synchronization & Manometer Balancer

Factory intake depression specifications (240 mmHg), electronic fuel pump pressure testing (43.5 PSI), injector resistance, and interactive multi-column manometer balancing.

Warm Idle: 1,350 - 1,450 RPM

Quick Workshop Diagnostic Presets

Simulate Throttle Linkage Asymmetry, Hunting Idle, or Intake Boot Vacuum Leaks

OPTIMAL SYNCHRONIZATION: BALANCED (Δ ≤ 10 mmHg)

Diagnostics:Max Differential: Δ 0 mmHg (Factory Max Tolerance: ≤ 10 mmHg)

All 1 throttle plates pull uniform intake depression within factory engineering tolerance (≤ 10 mmHg / 1.33 kPa). Delivers immediate linear throttle pickup, silky smooth idle, uniform cylinder torque pulses, and balanced exhaust temperatures.

Workshop Multi-Column Fluid Manometer

Damped intake depression columns. Target spec: 240 mmHg (±10 mmHg) at warm idle (1,350 - 1,450 RPM).

Reference: Single Throttle Body (Baseline)

Mechanism: Bypass Screws

CYL #1

MASTER REF

240mmHg

32.0 kPa · 9.4 inHg

±0 mmHg (Exact Target)

Fixed Reference Master. Synchronize all slave throttle bodies to match this column.

Vacuum Take-Off Ports: Intake manifold vacuum test port capped with rubber seal

Damping Protocol: Restrictor valves must be adjusted until columns oscillate no more than ±5 mmHg per intake stroke.

Fuel Pump Pressure & 5-Min Hold Test

EFI Pressure Rail

Running Fuel Pressure

43.5 PSI(3.00 bar)

OEM Running Spec

43.5 PSI (±3 PSI)

PASS: WITHIN OEM RUNNING SPEC

Fuel pump delivery pressure is 43.5 PSI (Factory spec: 43.5 PSI ± 3 PSI / 3 bar). High-pressure regulator and pump rotor operating within factory design threshold.

Connect mechanical gauge to the quick-disconnect fuel rail fitting using an OEM banjo or T-adapter.

Fuel Injector Resistance & Induction Specs

Multimeter Bench Check

OEM Injector Solenoid Resistance

11.5 - 12.5 Ω at 20°C

Measure across injector 2-pin harness socket with ignition OFF. Internal coil resistance increases by ~0.4% per °C rise above 20°C (68°F). Replace injector if resistance reads open (> 100 kΩ) or shorted (< 2 Ω).

Bore Diameter

24 mm

Operating Temp

80°C (176°F)

Induction Type

PGM-FI Electronic Fuel Injection with 24mm/38mm Keihin Throttle Body

Injector O-rings must be lubricated with a light coat of clean engine oil before seating into fuel rail.

4-Step Throttle Body Synchronization Protocol

Official workshop manual step-by-step checklist. Mark each step as you complete it on the workbench.

0 of 4 Steps Complete

1CLICK TO MARK DONE

Engine Pre-Flight Conditioning

Check and adjust valve clearances to spec before attempting sync. Ensure air filter is clean, spark plugs are fresh, and engine is fully warmed to operating temperature (warm idle).

2CLICK TO MARK DONE

Manometer Connection & Damping

Connect 1-column liquid or digital manometer hoses to Intake manifold vacuum test port capped with rubber seal. Adjust in-line hose restrictor valves to dampen rapid intake pulsation until fluid columns stabilize.

3CLICK TO MARK DONE

Balance Screw Calibration

With engine idling at 1,350 - 1,450 RPM, identify Single Throttle Body (Baseline). Adjust Idle air bypass brass screw with IACV (Idle Air Control Valve) until all cylinder columns are within 0 mmHg (0.00 kPa) of the master reference.

4CLICK TO MARK DONE

Throttle Blip & Locknut Verification

Blip throttle to 3,000 RPM 2–3 times and verify columns return evenly to idle balance. Tighten any balance screw locknuts securely, re-install rubber vacuum sealing caps, and verify idle speed.

Shop Carb & Throttle Body Cleaners→Shop Multi-Column Manometers & Sync Tools→Shop EFI Fuel Pressure Test Gauge Kits→

Official NHTSA Safety Recalls & Technical Bulletins

0 Open Campaigns (Clean)

U.S. Department of Transportation compliance database (Title 49 U.S.C. Chapter 301).

Verify VIN on NHTSA.gov

No Active Federal Safety Recalls Reported

The U.S. DOT National Highway Traffic Safety Administration (NHTSA) records zero open safety recall campaigns for the 2023 Honda Grom (MSX125) platform. Always check your individual 17-digit VIN at an authorized dealership or via NHTSA.gov for individual recall completions.