1987 Polaris Trail Boss 250: The Ultimate Diyer'S Restoration & Care

There’s a special kind of satisfaction that comes from keeping a classic piece of machinery alive and kicking. If you own a 1987 Polaris Trail Boss 250, you know exactly what we’re talking about. That unmistakable two-stroke sound, the simple-yet-tough engineering, and the pure, unfiltered fun it delivers on the trail are timeless.

But let’s be honest, keeping a quad from this era in top form isn’t always a walk in the park. Parts can be tricky to find, and a few mechanical gremlins are bound to pop up.

We promise this comprehensive guide will give you the confidence and expert knowledge to tackle common issues, perform critical maintenance, and truly understand your vintage ride. This isn’t just about fixing what’s broken; it’s about preserving a piece of off-road history.

In this ultimate 1987 Polaris Trail Boss 250 guide, we’ll cover its unique history, walk through an essential pre-ride checklist, diagnose the most common problems you’ll face, and share some pro tips for keeping it ripping for decades to come.

A Trailblazing Legend: Understanding the 1987 Polaris Trail Boss 250

To truly appreciate your machine, you have to know where it came from. The Polaris Trail Boss wasn’t just another ATV; it was a game-changer. When it debuted in 1985, it introduced features that are now standard, like an automatic transmission (Polaris Variable Transmission – PVT) and long-travel suspension, making ATVs accessible to a much wider audience.

The 1987 model carried that torch, cementing its place in off-road lore. It was a bridge between purely utilitarian farm quads and the high-performance sport machines that would come later.

Key Specifications and Features

Understanding the bones of your machine is the first step in mastering its maintenance. Here’s a quick look at what makes the ’87 Trail Boss tick:

Engine: A reliable, air-cooled 244cc Fuji two-stroke, single-cylinder engine. This is the heart of the beast, known for its simple design and peppy power delivery.
Transmission: The revolutionary Polaris Variable Transmission (PVT). This automatic system means no shifting gears, just press the throttle and go. It has Forward, Neutral, and Reverse.
Drive System: A simple and effective chain drive to the rear wheels.
Suspension: MacPherson strut front suspension with 6.25 inches of travel and a progressive-rate swingarm rear with 8.5 inches of travel. This was plush for its time!
Brakes: Hydraulic disc brakes on the front and rear, offering solid stopping power.

The primary benefits of the 1987 Polaris Trail Boss 250 were its ease of use and rugged simplicity. It was a machine you could work on with a basic set of tools in your garage, a quality that makes it a favorite among DIYers today.

Your Pre-Ride Ritual: The Essential 1987 Polaris Trail Boss 250 Care Guide

The most important maintenance you can do happens in the five minutes before you fire it up. A consistent pre-ride inspection prevents minor issues from becoming major, trail-ending failures. These are the 1987 Polaris Trail Boss 250 best practices for reliability.

Make this a habit. We call it the T-CLOCS checklist, a term borrowed from our two-wheeled friends, and it’s perfect for your quad.

T – Tires & Wheels: Check the air pressure. Old-school balloon tires on these models are typically happy around 3-5 PSI. Look for cracks in the sidewalls and ensure no lug nuts are loose.
C – Controls & Cables: Squeeze the brake levers. Do they feel firm, not spongy? Test the throttle—it should snap back crisply when you let go. If it’s sticky, lubricate the cable immediately.
L – Lights & Electrics: Test the headlight (if equipped) and the taillight. Check the kill switch to ensure it functions correctly. A faulty kill switch is a common no-spark culprit.
O – Oil & Fluids: This is a two-stroke, so your primary concern is the two-stroke injection oil tank level. Never let it run dry! Also, check the transmission oil level using the dipstick and look under the machine for any obvious brake fluid or gear oil leaks.
C – Chain & Chassis: Inspect the drive chain. It should have about an inch of slack. Too tight wears out sprockets; too loose and it can fall off. Look over the frame for any cracks, especially around suspension mounts.
S – Stands (or Parking Brake): Ensure the parking brake engages and holds the machine firmly in place.

Troubleshooting Common Problems with the 1987 Polaris Trail Boss 250

Even the best-kept machines have bad days. Over the years, we’ve seen it all. Here’s a rundown of the most frequent issues you’ll encounter and how to start diagnosing them. This is your go-to section for solving common problems with the 1987 Polaris Trail Boss 250.

Problem 1: It Won’t Start or Has a Weak Spark

This is the number one issue for any vintage two-stroke. The solution almost always comes down to three things: fuel, spark, or air.

Check the Spark: Get an inline spark tester—it’s a cheap and invaluable tool. If you have a weak or non-existent spark, the first culprits are the spark plug itself, the plug cap, or the kill switch.
Stator Issues: The lighting and ignition systems run off different coils on the stator. If your lights work but you have no spark, it can point to a failed ignition source coil on the stator.
Safety Switches: Remember the brake safety switch. You must hold a brake lever for the electric start to engage. Sometimes these switches get gummed up and fail.

Problem 2: The Engine Bogs Down Under Load

If it idles fine but sputters or dies when you give it gas, you likely have a fuel delivery problem. This is a classic symptom of a dirty carburetor.

Clogged Main Jet: The main jet in your Mikuni carburetor handles fuel flow at higher RPMs. Ethanol in modern fuel can leave deposits that clog this tiny orifice. A thorough carb cleaning is often the cure.
Fuel Filter: There should be an inline fuel filter between the tank and the carb. If it looks dirty or you don’t know when it was last changed, replace it. It’s a five-dollar fix that can save you a headache.
Air Leaks: A cracked intake boot between the carburetor and the engine can lean out the mixture and cause bogging. With the engine idling, carefully spray a little carb cleaner around the boot. If the RPMs change, you’ve found your leak.

Problem 3: The Brakes Feel Spongy or Weak

Don’t neglect your brakes. The single-lever system on the Trail Boss operates all three disc brakes, so proper function is critical.

Spongy brakes are almost always caused by air in the hydraulic lines. You’ll need to bleed the system. Start with the caliper furthest from the master cylinder (usually the rear) and work your way closer. Use a bottle of fresh DOT 3 brake fluid and a brake bleeding kit to make the job clean and easy.

How to Keep Your 1987 Polaris Trail Boss 250 Running Strong: Key Maintenance Tips

Beyond the pre-ride check, a few periodic tasks will dramatically extend the life of your Trail Boss. Here are some essential 1987 polaris trail boss 250 tips for long-term health.

Mastering the Two-Stroke Heart

The two-stroke engine is both simple and sensitive. Treat it right, and it will reward you.

Oil Injection vs. Pre-Mix: The stock oil injection system is convenient, but on a machine this old, the pump can fail. A failure means the engine gets no oil, leading to catastrophic seizure. Many owners choose to disable the system and switch to pre-mixing their gas and oil at a 40:1 ratio. It’s a little extra work but provides total peace of mind.
Air Filter Care: The foam air filter is your engine’s only defense against dirt. Clean it regularly with filter cleaner and re-oil it with proper foam filter oil. A dirty filter chokes the engine, and a torn one will destroy it.

Transmission and Drivetrain Service

The PVT transmission is robust but not invincible. The fluid inside the gearbox needs attention.

Change the transmission fluid at least once a season with a quality 80W-90 gear lube. The process is simple: remove the drain plug, let the old oil out, replace the plug, and refill through the dipstick hole until it reaches the correct level. This simple service keeps gears and bearings happy.

Smart Upgrades & Sustainable Riding Practices

Owning a classic doesn’t mean you can’t make smart improvements. A few modern touches can enhance reliability and your riding experience. This is how you create a more sustainable 1987 polaris trail boss 250.

Modern Touches for a Vintage Ride

Tires: Tire technology has come a long way since 1987. A new set of modern, 6-ply rated tires will provide vastly improved puncture resistance and traction compared to old, cracked originals.
LED Lighting: If you ride at dusk, swapping the old incandescent headlight bulb for a low-draw LED equivalent can make a huge difference without taxing the old stator.
Eco-Friendly Fluids: When possible, opt for biodegradable two-stroke oil and chain lube. These are much better for the environment and perform just as well, making for a more eco-friendly 1987 polaris trail boss 250 experience on the trails.

Ride Responsibly

Part of sustainable ownership is protecting the places we ride. Always stay on marked trails, avoid sensitive areas, and pack out everything you pack in. A well-maintained, quiet machine is the best ambassador for our sport.

Frequently Asked Questions About the 1987 Polaris Trail Boss 250

What is a 1987 Polaris Trail Boss 250 worth?

Value depends heavily on condition. A non-running project might be worth a couple of hundred dollars, while a pristine, fully restored example could fetch $1,500 to $2,500 or more to the right collector. Most running, decent-condition models fall in the $800-$1,200 range.

Are parts hard to find for this model?

Yes and no. Many common wear items like brake pads, chains, sprockets, and carburetor rebuild kits are readily available from aftermarket suppliers. However, model-specific plastic body parts, engine cases, and certain electrical components can be very difficult to find and often require searching eBay or ATV salvage yards.

What is the correct gas-to-oil ratio if I pre-mix?

A 40:1 ratio is a safe and widely accepted standard for this engine. This translates to 3.2 ounces of high-quality two-stroke oil for every 1 gallon of gasoline. Always use oil designed for air-cooled, injector or pre-mix applications.

Owning and maintaining a 1987 Polaris Trail Boss 250 is a rewarding journey. It connects you to a simpler time in off-roading and teaches you the fundamentals of mechanics in a way modern, complex machines can’t.

Use this guide as your roadmap. Take your time, be safe, and don’t be afraid to get your hands dirty. The thrill of bringing that classic two-stroke back to life and hitting the trail is an experience every true enthusiast should have. Now get out there, stay safe, and keep that legend ripping!

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Thomas Corle

Founder & Automobile expert at FatBoysOffroad

Automobile expert and off-road enthusiast, sharing in-depth knowledge of vehicles, gear, and adventures. Helping readers make smart decisions and enjoy the thrill of off-roading safely and confidently.