A Legendary CR500 Reimagined for 2026
There is something unmistakable about a Honda CR500 engine coming to life. The sound, the torque, and the raw character of a big-bore two-stroke have made the CR500 a favorite among riders and builders long after its original production era.
But what happens when that legendary two-stroke power is placed inside a modern motocross chassis—and paired with a NIBBI Racing PWK38 carburetor?
That is exactly what BVC Off-Road brought to Nomad MX in Arizona, where professional rider Blake Wharton had the opportunity to ride a unique Honda CR500 project: a rebuilt 1990 CR500 two-stroke engine installed in a 2026 Honda CRF450R chassis.
Right at the center of the engine’s fuel-delivery setup was a NIBBI Racing PWK38 carburetor. For us at NIBBI Racing, this is the kind of build we love to see. It combines creative engineering, serious performance hardware, careful tuning, and the simple goal of making a motorcycle exciting to ride.
A 1990 CR500 Engine Meets a Modern CRF450R Chassis
The BVC Off-Road project takes two very different generations of Honda motocross technology and brings them together.
According to the video, the bike uses a rebuilt 1990 Honda CR500 engine inside a 2026 CRF450R chassis. Instead of extensively modifying the modern frame, BVC developed a bolt-in approach featuring billet engine cradles and a billet headstay.
The result is an interesting combination: classic 500cc two-stroke character paired with the geometry and handling characteristics of a much newer motocross platform.
BVC has been developing CR500 conversion solutions for modern Honda chassis for several years.
Installing the engine is only part of a build like this. A big-bore two-stroke still needs the right intake, fuel-delivery setup, and tuning to perform the way the builder intends. For this project, BVC paired its custom intake configuration with a NIBBI Racing PWK38.
The NIBBI Racing PWK38 Carburetor in the CR500 Build
At approximately 2:00 in the video, BVC introduces the rebuilt CR500 engine and points out an important component:
“We’ve also got our PWK NIBBI carb here.”
That carburetor is the NIBBI Racing PWK38.
Seeing a PWK38 used in a project like this matters because it is not simply a carburetor sitting on a display bike. The motorcycle was brought to the track and ridden by Blake Wharton as part of BVC’s real-world testing of the complete setup, including its new intake and airbox design.
The NIBBI PWK38 has a 38 mm inner diameter and is listed by NIBBI Racing for 450–500cc engine applications. Its performance-focused PWK architecture is designed to provide strong airflow while giving builders multiple ways to adjust fuel delivery for their specific setup.
That adjustability is particularly important with custom motorcycles. Engine condition, exhaust design, intake configuration, temperature, elevation, and riding style can all affect the jetting a motorcycle requires. There is rarely one carburetor setting that is ideal for every modified engine.
A performance carburetor should not only flow air—it should give the builder room to tune.
What Blake Wharton Thought of the CR500
A specification sheet can tell you how a component is designed. A track session tells you how the complete motorcycle behaves.
After riding the CR500 at Nomad MX, Blake described the bike positively and specifically mentioned the carburetor setup. During the video, he noted that the 500 was running well at the elevation and in the conditions they were riding. Later, after more time on the bike, he explained:
“We got the NIBBI carb running good, tuned up a little bit.”
That distinction is important. We do not want to claim that one carburetor alone is responsible for the performance of an entire custom motorcycle. The final behavior of a CR500 depends on the engine, jetting, intake, exhaust, chassis, environmental conditions, and many other variables.
What this build demonstrates is that the NIBBI Racing PWK38 can be integrated into a serious custom 500cc two-stroke project and tuned as part of the overall package.
Blake described the motorcycle as having the strong bottom-end and mid-range pull expected from a 500cc two-stroke. He also noted that these engines tend to flatten out toward the top, making it important to ride within the engine’s strong torque range.
That is classic CR500 character—delivered through a very modern motorcycle.
Why Carburetor Tuning Matters on a CR500 Build
A carburetor has a demanding job. It must meter fuel in relation to the air entering the engine across changing throttle positions, engine speeds, and loads. On a high-performance two-stroke, getting that relationship right is especially important.
This is also why simply installing a larger carburetor does not automatically create better performance. The carburetor needs to suit the engine and, just as importantly, it needs to be properly tuned.
The PWK38 provides multiple adjustment possibilities to help builders dial in fuel delivery. NIBBI’s PWK design includes adjustable fuel-mixture and idle settings, while interchangeable jetting allows the setup to be adapted to different engines and riding requirements.
The NIBBI Racing PWK38 package includes three main jets—#138, #132, and #130—along with a #35 pilot jet. Different builds may require different jetting, so these supplied components should be treated as tuning options rather than guaranteed settings for every motorcycle.
What Makes the NIBBI PWK38 a Performance Option?
The PWK38 was developed for riders and builders who want more than basic fuel delivery. Several design elements make it particularly relevant to modified off-road motorcycles and performance projects.
38 mm Performance-Focused Design
The NIBBI Racing PWK38 features a 38 mm inner diameter, a 46 mm outer-diameter spigot, and a 63 mm outer-diameter intake.
NIBBI Racing lists this model for 450–500cc engine applications, making it a natural option to consider for large-displacement performance builds when the engine and intake requirements are compatible. Fitment and jetting should always be verified for the specific motorcycle.
Adjustable Fuel Delivery
Modified motorcycles rarely operate exactly like stock machines. Changes to displacement, porting, exhaust, intake, airbox design, and riding environment can change an engine’s fuel requirements.
The PWK platform gives builders the ability to make adjustments instead of relying on a completely fixed configuration. That flexibility is one of the reasons PWK-style carburetors are useful in performance builds.
Designed for Responsive Airflow
The NIBBI PWK series uses an airflow-focused throttle-valve design intended to support responsive engine operation. The PWK38 also incorporates a power-jet system designed to provide additional fuel delivery under higher-speed operating conditions.
When correctly tuned for the engine, these features give builders another level of control over how the motorcycle responds.
Built for Demanding Off-Road Use
The PWK38 body is constructed from aluminum alloy with an anodized surface treatment. NIBBI uses this treatment to improve properties such as corrosion and wear resistance.
The PWK series also uses a service-friendly design intended to make disassembly and maintenance straightforward—an important consideration for motorcycles that are regularly tuned, serviced, and ridden off-road.
From Installation to Track Testing
One detail we particularly liked about the BVC Off-Road video was that the build was not treated as finished simply because all the parts were installed. The team tested it.
Blake rode the motorcycle on an actual motocross track. The carburetor was tuned. BVC evaluated its new intake and airbox design. The team listened to rider feedback.
That process represents what performance motorcycle building is really about. Good components provide the foundation, but proper installation, tuning, and testing turn those components into a complete motorcycle.
The conditions at Nomad MX also offered a useful real-world environment. Blake commented that the carburetor seemed to like the elevation and that the 500 was running well during the session.
Again, this should not be interpreted as a universal jetting recommendation. Temperature, altitude, engine modifications, and intake and exhaust configuration all influence carburetor settings. Instead, it shows what can happen when a performance carburetor is properly integrated and tuned for a specific build.
Vintage Two-Stroke Power Meets Modern Build Philosophy
The BVC CR500 represents something bigger than one motorcycle. It demonstrates why custom motorcycle building continues to attract riders around the world.
A 1990 CR500 engine and a 2026 CRF450R chassis come from completely different eras, yet thoughtful engineering allows the strengths of each to exist in one machine.
The engine provides the unmistakable torque and personality of a large-displacement two-stroke. The modern chassis brings contemporary handling and ergonomics. BVC’s conversion hardware connects those two worlds, and the NIBBI Racing PWK38 becomes part of the system that feeds that legendary engine.
This is exactly where performance aftermarket components should fit: not as modifications made simply for appearance, but as functional pieces selected to help builders create the motorcycle they want to ride.
A Build Made to Be Ridden
Blake’s feedback on the chassis was also interesting. One of the biggest concerns riders have when discussing CR500 conversions is vibration. Blake acknowledged the vibration inherent in a big two-stroke but said it was not as severe as he expected in the modern chassis.
He described the modern frame and CR500 engine as a good combination. That is important because this project is not trying to turn a CR500 into something it is not.
A 500cc two-stroke is still a 500cc two-stroke. It has huge torque. It has vibration. It has distinctive power delivery. It requires respect from the rider and attention from the builder.
The goal is to put that character into a package that takes advantage of modern motorcycle development. Judging from Blake’s track session, the result made for a memorable ride.
Watch Blake Wharton Ride the BVC CR500
Want to hear the bike and see the complete build in action? Watch “Blake Wharton Rides My 2026 Honda CR500”, featuring Blake Wharton and BVC Off-Road on YouTube.
The video covers the conversion hardware, custom intake setup, NIBBI Racing PWK carburetor, track testing, and Blake’s riding impressions. It is worth watching not only for the CR500 sound, but also for a closer look at what goes into making an unconventional two-stroke conversion work on the track.
Frequently Asked Questions
What carburetor is used on BVC Off-Road’s CR500 in the Blake Wharton video?
The build shown in the video uses a NIBBI Racing PWK38 carburetor with BVC Off-Road’s custom intake configuration. The bike combines a rebuilt 1990 Honda CR500 engine with a 2026 Honda CRF450R chassis.
Is the NIBBI PWK38 suitable for 500cc engines?
NIBBI Racing lists the PWK38 for 450–500cc engine applications. Compatibility still depends on the specific engine, intake dimensions, modifications, and other components, so fitment should be checked before installation.
What size is the NIBBI Racing PWK38?
The PWK38 has a 38 mm inner-diameter spigot, a 46 mm outer-diameter spigot, and a 63 mm outer-diameter intake according to NIBBI Racing’s specifications.
Can the NIBBI PWK38 be tuned?
Yes. The PWK platform includes multiple adjustable fuel-delivery features, and the PWK38 package includes interchangeable main and pilot jets. Proper jetting depends on the motorcycle, engine modifications, altitude, temperature, and intake and exhaust configuration.
Does installing a PWK38 automatically increase horsepower?
No specific horsepower increase should be assumed simply from installing a carburetor. Performance depends on the complete engine setup and correct tuning. A performance carburetor can support the engine’s fuel-delivery and airflow requirements when appropriately selected and tuned, but results vary by application.
What engine was used in the BVC Off-Road 2026 CR500 build?
According to the video, BVC installed a rebuilt 1990 Honda CR500 two-stroke engine into a 2026 Honda CRF450R chassis using its bolt-in conversion approach.
What did Blake Wharton say about the NIBBI carburetor?
During his post-ride comments, Blake said they had the NIBBI carburetor “running good” after tuning it. He also described the motorcycle as delivering the strong bottom-end and mid-range power associated with a 500cc two-stroke.
Is the PWK38 only for Honda CR500 builds?
No. The PWK38 is not a CR500-specific carburetor. NIBBI Racing lists it for 450–500cc applications, but actual compatibility and required tuning depend on the engine and motorcycle configuration.
Build Your Next Project with NIBBI Racing
The BVC Off-Road CR500 is a great reminder of what makes motorcycle modification exciting. Take an iconic engine. Combine it with modern engineering. Choose components that can be adapted and tuned to the project. Then take the motorcycle out and actually ride it.
For the BVC build tested by Blake Wharton, the NIBBI Racing PWK38 carburetor was part of that formula.
At NIBBI Racing, we design performance carburetors for riders, tuners, and builders who want control over their setup. From everyday off-road machines to ambitious projects like this modern-chassis CR500, our goal is to provide performance-focused components that can be tuned for the demands of the build.
If you are working on a 450–500cc project and considering a performance carburetor, explore the NIBBI Racing PWK38 and check its dimensions and specifications against your setup.
Because a great build is not just about putting parts together. It is about making them work together.
