Honda 450RL Performance guide
Technical Reference Guide
Performance Mods Guide
Honda CRF 450L · CRF 450RL · Intake, Exhaust, ECU & Cooling · Real-World Info
CLOSED COURSE COMPETITION USE ONLY. Removing or modifying any sound or emissions control system makes a vehicle illegal on public roadways. Not CARB/EPA compliant. Modify at your own risk.
Bikes Covered
Honda CRF 450L (2019+)
Honda CRF 450RL (2019+)
Real-World Numbers — CRF 450L / RL Platform
What These Bikes Actually Make
Honda
CRF 450RL — Stock vs. Full Bolt-On
ECU tune + slip-on exhaust + airbox mod
Stock
~33–35 hp
Modified
~40–43 hp
+7–10 hp — bolt-on mods only
Honda
CRF 450RL — R Cam Conversion
GET ECU + R Cam kit + full exhaust
Stock
~33–35 hp
R Cam Build
~54–55 hp
+20–22 hp — nearly 60% gain at the wheel
01 — Non-US / Non-CA Bikes: Detuning Delete
Bikes not sold in the US or Canada come with a severely detuned ECU and a choked throttle body connecting tube and airbox lid. Simply swapping those two OEM parts to US-spec restores full airflow — then pair with an ECU of your choice. The O2 sensor on the header is not a concern once you’re running an aftermarket ECU. Do this before any other mod.
✓ Required for Non-US/CA Bikes
US-Spec Air Cleaner Connecting Tube
OEM Part: 17253-MKE-A50 — TUBE, AIR CLEANER CONNECTING. Replaces the choked non-US throttle body tube.
Pros
- +Restores full throttle body airflow
- +OEM Honda part — direct fit
- +Required step before ECU tuning
Cons
- −US/CA bikes already have this — no action needed
✓ Required for Non-US/CA Bikes
US-Spec Airbox Lid Sub-Assembly
OEM Part: 17234-MKE-A50 — LID SUB-ASSY., AIR CLEANER. Replaces the restrictive non-US lid.
Pros
- +Fully opens airbox breathing
- +OEM Honda part — direct fit
- +Free-flowing without cutting or modifying
Cons
- −US/CA bikes already have this — no action needed
02 — Intake System
✓ Taco Moto Recommends
High-Flow Air Filter
Pros
- +Better flow than stock foam at all RPMs
- +Easier to clean and re-oil
- +Twin Air, Uni, No-Toil — all direct fit
- +Maintenance upgrade as much as a performance one
Cons
- −Marginal power gain on its own
✓ Taco Moto Recommends
Airbox Lid Mod / Removal
US/CA bikes already have an open lid. This applies to bikes where the lid has been swapped or restricted. Stock US-spec lid is fine as-is.
Pros
- +Improved mid-to-top airflow
- +Free mod
Cons
- −Louder intake sound
- −Fuel correction required
.
PAIR Valve Block-Off
Removes secondary air injection. Cleans up decel popping before a tune. Not a power mod — purely drivability and noise improvement.
Pros
- +Eliminates decel pop and backfire
- +Removes unnecessary complexity
- +Low cost
Cons
- −No measurable power gain
- −ECU tune handles decel pop more completely anyway
03 — Exhaust System
Honda wrapped the 450L/RL exhaust in restrictions to meet 80dB street noise limits. A slip-on alone frees up noticeable mid-to-top power — but always pair with an ECU tune. Running open exhaust on a stock ECU leaves fueling uncorrected.
★ Best Value Pick
Slip-On Muffler
FMF, Yoshimura, Pro Circuit, HGS — all make direct-fit options. Biggest power-per-dollar on exhaust for a stock-motor bike.
Pros
- +Best bang for the dollar on exhaust
- +Frees up mid and top-end breathing
- +Retains stock header — easy bolt-on
Cons
- −Louder
- −Fuel correction required
- −Some options may melt turn signal
.
Full Exhaust System
Worth it on a full build — R Cam conversion or heavily modified motor. Marginal gain over a slip-on on a stock engine.
Pros
- +Opens entire exhaust path
- +Meaningful gain on heavily modified motors
- +Weight savings over stock
Cons
- −Marginal gain over slip-on on stock motor
- −Complex install
- −Fuel correction required
✗ Don’t Skip This Step
Exhaust Without a Tune
Opening up the exhaust on a stock ECU leaves fueling uncorrected. You’ll run leaner, gain nothing meaningful, and stress the motor.
What You Think Happens
- +More power, better sound
What Actually Happens
- −Runs leaner — no real power gain
- −Increased engine stress
- −Tune first, exhaust second
04 — ECU, Tuners & Mapping
The stock CRF 450L/RL ECU is Honda’s biggest restriction on the platform — tuned soft and lean to meet emissions and noise standards. ECU tuning is the single most impactful mod on this bike. Do it before anything else. Every other mod you bolt on is being wasted without a proper tune.
★ Best Overall — TacoGET ECU
GET ECU — Full ECU Replacement
Required for R Cam conversion. Buy from Taco Moto: lifetime map + hardware warranty.
Pros
- +Full ECU swap — not limited by OEM hardware
- +Trail, Enduro and Race maps switchable on the fly
- +WiGet Bluetooth app — adjust power, throttle feel, engine braking from your phone
- +Remote map updates from GET as bikes evolve
- +Only ECU with proper R Cam map
- +Lifetime warranty from Taco Moto
Cons
- −Premium cost
★ Taco Moto — Ship-In Reflash
TacoFlash — Stock ECU Reflash
Pros
- +Best bang for the dollar
- +Removes emissions restrictions, fixes fueling
- +Raises rev limit
- +No added hardware — retains stock Honda ECU
- +Lifetime Taco Moto map support
Cons
- −No on-the-fly map switching
- −Must ship ECU in for map changes
- −Cannot support R Cam conversion
.
Power Commander V
Piggyback tuner — works on top of the stock ECU. Good if you want user-adjustable fueling without shipping the ECU. No ignition timing control.
Pros
- +User-adjustable via Dynojet software
- +No shipping required
- +Custom tune at Dynojet shops nationwide
- +Bypasses if unit fails
Cons
- −Fuel correction only — no ignition timing
- −Adds hardware to bike
- −Cannot support R Cam conversion
.
EJK / Dobeck Fuel Controller
Pros
- +Low cost entry point
- +User-adjustable fuel trims via onboard buttons
- +Can be bypassed if unit fails
Cons
- −Fuel correction only — no ignition timing
- −Modest gains vs. other options
- −Adds hardware to bike
✓ Free Tips
No-Cost Drivability Fixes
+Throttle stop check — some 450RL builds have a partial throttle stop from the factory. Verify yours and remove if present for full throttle travel.
+Idle speed bump — stock idle can be set low. Bumping it slightly smooths cold-start behavior and reduces stalling in technical terrain.
+Ride a lower gear — keeps RPMs in a stable zone on tight trails before any ECU work.
05 — R Cam Conversion — The Big One
The CRF 450L/RL shares its bottom end with the CRF 450R motocross bike but Honda installed a detuned camshaft with reduced lift and duration to tame power and meet emissions. Swapping in the 450R-spec cam is the single biggest power move on this platform. GET ECU is required — the stock ECU and reflashes cannot map this cam profile correctly.
★ Taco Moto R Cam Conversion Kit — $799
450R Cam Conversion
GET ECU required. With a proper tune this is a ~54–55 WHP build — nearly double stock output. Head work recommended for best results.
Pros
- +~54–55 WHP with GET ECU + full exhaust
- +Transforms the bike’s character entirely
- +Uses 450R race cam profile — proven, reliable
- +Best power mod available on this platform
Cons
- −GET ECU required — not optional
- −Mechanical install — head work recommended
- −Higher total build cost
⚠ Important
R Cam Without GET ECU = Wasted Money
+The stock ECU and all reflash options use conservative ignition timing maps not designed for the 450R cam’s more aggressive lift and duration.
+The GET ECU’s R Cam-specific map optimizes fueling across the RPM range and properly raises the rev limit to match the cam’s characteristics.
+You can run the cam without the GET but you won’t see the real numbers and may experience flat power and potential detonation.
06 — Cooling System
The most common cooling question on this platform is whether to remove the thermostat. The short answer: don’t. The t-stat is a critical part of the fuel injection system, not just the cooling system.
✗ Do NOT Recommend
Thermostat Delete
Optimal combustion happens with coolant in the 190–215°F range. The t-stat keeps the system there. Without it in cold conditions, the ECU auto-richens — causing a cascade of problems.
Possible Benefits
- +Up to 10–20°F coolant temp reduction in hot conditions (Jimmy Lewis tested this)
- +Possibly worth it if riding exclusively in 80°F+ with no cold weather use
Downsides in Cold / Mixed Conditions
- −ECU over-richens — power loss, poor throttle response
- −Cylinder oil washing — accelerated wear
- −Piston and valve carbon buildup
- −Fuel contamination in engine oil (extreme cases)
- −Added stress on head gaskets and seals
✓ Taco Moto Recommends
Cooling System Optimization
These are the actual cooling mods that make a real difference — all run with the stock thermostat intact.
What Actually Works
- +Open exhaust — engine runs cooler and more efficiently
- +Correct ECU tune — proper fueling reduces heat load
- +Samco silicone hoses — better heat tolerance and flow
- +OAT coolant (silicate-free) — Zerex G-30, Peak OE, Dex-Cool. Silicates coat the temp sensor and form scale
- +2.0 bar rad cap — raises boil point to 299°F. Upgrade hoses if doing this
- +Straighten bent rad fins — free, meaningful airflow improvement
- +Good oil — Motul 7100. Clutch generates serious heat in slow tech
Remember
- −Most heat in slow tech comes from clutch slip — rider technique matters more than hardware
- −Bike running hot when it shouldn’t? You have an underlying problem — find it, don’t band-aid it with a t-stat delete
✓ Coolant Notes
Coolant Change Interval & Mix
+Change coolant every 3–4 years. Between changes, flush with 80/20 vinegar / distilled water.
+50/50 premix with OAT ethylene glycol — free of silicate, nitrite, amine, borate, and phosphates.
+Run a coolant overflow bottle — catches overflow and prevents coolant loss on the trail.
+Summer-only riders: if you exclusively ride in 80°F+ with no cold weather use, removing the t-stat and running distilled water + Water Wetter is a reasonable option.
Taco Moto — Las Vegas, NV
GET ECU Factory Authorized Dealer
TacoFlash Ship-In Reflash
R Cam Conversion Kit — $799
Lifetime Map Support