1989 Duncan Built Yamaha Banshee

The 1989 Duncan Built Yamaha Banshee is a modified version of the iconic Yamaha Banshee, featuring performance enhancements and upgrades that were made by Duncan Racing, a company well-known in the ATV world for building high-performance parts and racing modifications. The 1989 Yamaha Banshee itself is already a powerful machine, but when modified by Duncan Racing, it takes the performance, handling, and overall experience to another level.

Here’s an overview of the 1989 Duncan Built Yamaha Banshee:

Stock 1989 Yamaha Banshee Specifications:

Before diving into the modifications, it’s useful to understand the base specifications of the 1989 Yamaha Banshee:

Engine:

• Type: Twin-cylinder, 2-stroke, liquid-cooled
• Displacement: 348cc (172cc per cylinder)
• Compression: Typically 6.7:1 (stock)
• Fuel System: Dual 28mm Mikuni carburetors
• Ignition: CDI
• Lubrication: Premix or Yamaha Autolube system

Transmission:

• Type: 6-speed manual
• Final Drive: Chain

Suspension:

• Front: Independent double-wishbone, 8.1 inches of travel
• Rear: Monoshock, 9.1 inches of travel

Brakes:

• Front: Dual disc brakes
• Rear: Single disc brake

Weight:

• Dry Weight: 370 lbs (168 kg)

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Duncan Racing Modifications (1989):

When Duncan Racing gets their hands on a Yamaha Banshee, they typically upgrade the motor, suspension, exhaust, and other critical areas to create a truly race-worthy machine. Some of the typical upgrades you might find on a Duncan Built Yamaha Banshee from 1989 would include:

Engine Modifications:

• Cylinders: Duncan Racing often ported the cylinders for increased power and better throttle response. This would result in an increase in overall horsepower.
• Piston and Cylinder Kits: They may have installed high-performance pistons or big-bore kits, such as 350cc or 370cc kits, which would make the engine even more powerful.
• Exhaust System: Duncan Racing is known for their custom exhaust systems, which could include their own brand of expansion chambers for better power delivery and top-end performance.
• Carburetors: The carburetors could have been upgraded to larger 34mm or 36mm Mikuni units, allowing for better fuel delivery and increased performance.

Suspension Modifications:

• Upgraded Shocks: The stock suspension would likely have been upgraded to aftermarket shocks from brands like Elka, Works, or Fox Racing, improving the handling and performance on rough terrain.
• A-arms and Swingarm: Performance A-arms or extended A-arms would have been added for better handling, particularly in cornering, as well as additional ground clearance for rough trails or racing environments.

Other Modifications:

• Reed Valves: To improve intake flow, the stock reed valves might have been replaced with high-performance reed valve kits, such as those from V-Force or Boyesen.
• Clutching: A high-performance clutch setup, including stronger springs and more durable components, could have been used to handle the increased power from the engine modifications.
• Brake System: For improved stopping power, the braking system could have been upgraded with stronger, race-grade disc brakes or upgraded calipers.
• Tires and Wheels: Racing-specific tires and wheels, possibly with beadlock rims for better durability and grip in high-performance conditions, might also be part of the build.

Visual Modifications:

• Custom Graphics and Color Schemes: Duncan Racing might have customized the appearance with custom graphics kits, giving the Banshee a distinctive, race-ready look.
• Frame and Plastic: Depending on the owner’s preferences, they might have swapped the plastics for aftermarket colors or added custom reinforcements to the frame for additional strength and durability during racing.

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Performance:

• With these modifications, a Duncan Built 1989 Yamaha Banshee would have significantly more horsepower than the stock version, possibly pushing 50-60+ horsepower, depending on the modifications. The performance would be dramatically improved in terms of acceleration, top-end speed, and overall responsiveness.
• The handling would also be much more precise, especially with upgraded suspension components and a more aggressive geometry.

Purpose:

The Duncan Built Banshee would have been primarily intended for competitive racing or for experienced riders who wanted a powerful, highly responsive machine for off-road or motocross-style riding.

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Maintenance and Parts:

Owning a modified 1989 Duncan Built Yamaha Banshee requires attention to regular maintenance, especially with the higher-performance parts installed. Here are a few things to keep in mind:

• Oil and Fuel: As a 2-stroke, it requires pre-mixed fuel unless the stock oil injection system is still in place.
• Suspension: Regular maintenance on the shocks and suspension components is necessary to maintain optimal performance.
• Engine: With the engine modifications, keeping the carburetors tuned and ensuring the top-end is regularly checked for wear is essential for maintaining peak performance.

Value:

A 1989 Duncan Built Yamaha Banshee would hold a strong collector value for ATV enthusiasts, particularly those who are looking for a high-performance machine with racing history. The modifications and custom nature of the build make it a unique find in the used ATV market.