Yamaha Cold Air Intake — Install Guide

GT40 Marine | SKU GT40-YAM-INT-1819L | Yamaha 1.8L / 1.9L Cold Air Intake | Rev 1.0 — 2026-05-24

Fitment — Yamaha 1.8L / 1.9L 4-Cylinder Family

This cold air intake fits the entire Yamaha 1.8L (2008-2023) and 1.9L (2024+) 4-cylinder engine family across SVHO / SHO / HO trims. Fitment is determined by the intake manifold geometry + airbox mounting bosses shared across the platform.

SVHO / SHO Supercharged FX Family

2008-2026 FX SHO, FX SVHO, FX Cruiser SHO, FX Cruiser SVHO, FX Limited SVHO, FX HO, FX Cruiser HO

GP / FZR / FZS Performance Family

2009-2026 FZR, FZS, GP1800, GP1800R HO, GP1800R SVHO, GP HO, GP SVHO

VX Cruiser HO / Limited HO / VXR / VXS Touring Family

2011-2026 VX Cruiser HO, VX Limited HO, VXR, VXS

Not for: Yamaha 1.0L / 1.05L / 1.6L (smaller / legacy engines), Yamaha JetBlaster, Yamaha 4-stroke standup hulls. Confirm engine displacement (1.8L or 1.9L) on the engine cover plate before install.

Before You Start — Decision Tree

| # | Question | Branch |

|---|---|---|

| 1 | Engine cover plate shows 1.8L or 1.9L? | Continue |

| 2 | Are you running any kind of ECU tune? | SVHO gain compounds with tune (10-15 HP); naturally aspirated HO gain is 3-5 HP without tune |

| 3 | Is the OEM airbox modified or replaced already? | If yes, skip Step 3 airbox-removal procedure |

| 4 | Are you on saltwater? | Plan a 25-hour filter-cleaning interval (vs 50-hour freshwater); see Service section |

In the Box

• (1) GT40 carbon-fiber filter housing, gloss finish
• (1) High-flow filter element, pre-oiled
• (1) GT40-machined intake adapter for Yamaha 1.8L/1.9L mounting bosses
• (1) High-temperature silicone coupler, 3.5" ID, reinforced
• (2) T-bolt clamps, stainless 3.5"
• (4) M6 × 25 mm SHCS — adapter mounting
• (4) M6 stainless flat washers
• (1) Sensor harness extension, 8 inch
• (1) Install hardware bag — spare clamps, washers, zip ties
• (1) GT40 product registration card
• (1) This guide

Tools Required

• 8 mm / 10 mm / 13 mm sockets + ratchet, 3/8" drive
• T25 + T30 Torx drivers
• 5 mm hex (Allen) key
• 1/4" drive torque wrench, 5–25 Nm range
• Long Phillips screwdriver
• Trim removal tool
• Flashlight or headlamp
• Shop towels

Safety

1. Battery disconnected for the install duration
2. Cold engine only
3. Eye protection when removing existing intake hardware
4. No smoking / open flame
5. Marine-grade install only. Not for snowmobile or automotive use

If you are not comfortable with PWC engine bay work, take the install to a certified marine technician.

Pre-Install Checklist

• [ ] Watercraft on stable trailer or stand
• [ ] Battery negative disconnected and isolated
• [ ] Engine bay clean and dry
• [ ] Stock airbox routing photographed before disassembly
• [ ] Engine code confirmed (1.8L or 1.9L)

Step-by-Step Install

Step 1 — Access the Engine Bay

Remove the seat. On FX Cruiser hulls, two-person lift recommended due to seat weight.

Open the engine bay top hatch. Disconnect the battery negative terminal.

Step 2 — Identify the Stock Airbox

The Yamaha 1.8L/1.9L factory airbox sits on the engine port-side, secured by 3-4 M6 mounting bosses depending on trim. Key components to identify:

• IAT (intake air temperature) sensor in the airbox shell
• Air intake snorkel routing to the hull air intake
• Any harness retainers on the airbox underside

Photograph the assembly in stock form before disassembly.

Step 3 — Remove the Stock Airbox

1. Unplug the IAT sensor — squeeze plastic retainer, pull straight off
2. Disconnect harness retainer clips on the airbox underside
3. Loosen the airbox-to-engine outlet clamp
4. Remove 3-4 M6 SHCS securing airbox to engine bracket
5. Lift airbox out — set aside (retain if you may sell craft in stock form)

Step 4 — Install the GT40 Intake Adapter

1. Position the GT40-machined adapter on the engine mounting bosses
2. Thread 4 supplied M6 × 25 mm SHCS through adapter
3. Snug evenly, torque to 10 Nm (89 in-lb) in two passes
4. Verify adapter sits squarely on bosses — no rotational offset

Step 5 — Connect Engine Outlet to Adapter

1. Slide T-bolt clamps onto each end of supplied silicone coupler
2. Push coupler onto engine outlet, then onto GT40 adapter inlet
3. Torque T-bolt clamps to 5 Nm (44 in-lb) alternating in two passes
4. Pull-test joints — couplers should not slide

Step 6 — Install Filter Housing and Sensors

1. Slide carbon fiber housing over GT40 adapter neck
2. Tighten housing clamp to 5 Nm (44 in-lb)
3. Transfer IAT sensor from stock airbox to GT40 adapter threaded boss
4. Apply thin dab of dielectric grease to IAT threads
5. Torque IAT to 8 Nm (71 in-lb)
6. Reconnect IAT harness; use supplied 8 in. extension if routing is tight

Step 7 — Reassembly and First Start

1. Walk the engine bay — every fastener, every clamp
2. Reconnect battery negative — torque to 10 Nm (89 in-lb)
3. Start engine on trailer with cooling hose connected
4. Idle 60 seconds — listen for intake leaks
5. Scan with Yamaha YDS or compatible OBD diagnostic
6. Bring to 3000 RPM briefly — confirm smooth response

If clean: install complete.

Post-Install

Break-In

Filter element is pre-oiled. No break-in required. First 15 minutes of on-water operation may show slight idle richness as ECU adapts trim — normal.

Tuning

Plug-and-play with factory calibration. Modest gain on stock tune (3-5 HP on SVHO, 2-4 HP on HO).

For full Stage 2 / Stage 3 builds, pair with:

• Yamaha free-flow exhaust
• Yamaha intercooler kit (GT40-YAM-IC-1819L)
• Yamaha waterbox (GT40-YAM-WB-1819L)
• ECU tune from Yamaha-specific tuner

Filter Service

• Inspect every 25 hours (saltwater) or 50 hours (freshwater)
• Clean per filter manufacturer guidance — solvent wash + re-oil
• Replace at 200 hours or sooner if visible damage

Troubleshooting

| Symptom | Likely Cause | Fix |

|---|---|---|

| Lean stumble at low RPM | Coupler not seated | Recheck Step 5 |

| Check Engine + P0102 | IAT harness not clicked | Reseat retainer |

| Whistle above 4000 RPM | T-bolt clamp under-torqued | Retorque to 5 Nm |

| Filter housing vibrates | Adapter SHCS under-torqued | Retorque to 10 Nm |

Torque Reference Summary

| Fastener | Torque |

|---|---|

| Adapter M6 SHCS (4) | 10 Nm / 89 in-lb |

| Silicone coupler T-bolts | 5 Nm / 44 in-lb |

| IAT sensor | 8 Nm / 71 in-lb |

| Filter housing clamp | 5 Nm / 44 in-lb |

| Battery negative | 10 Nm / 89 in-lb |

Warranty

GT40 Marine warrants this kit free from defects for ninety (90) days. Does not cover improper installation, operation outside design intent, normal filter wear, or use outside fitment matrix.

Claims: support@gt40marine.com with order number, photos, and failure description.

Support

• Email: support@gt40marine.com
• Site: gt40marine.com
• Install help: include SKU, hull serial number, model year, and engine displacement (1.8L or 1.9L) in correspondence

Built in the United States. Designed for buyers who want the best.

This guide is © 2026 GT40 Marine. All rights reserved.