There’s something special about firing up a classic two-stroke ATV. That distinct smell, the snappy powerband, and the simple, rugged engineering—it’s a connection to a different era of off-roading. You probably agree that keeping a vintage machine like the 87 polaris trail boss running isn’t just a hobby; it’s a passion project that connects you directly to the nuts and bolts of your ride.
But let’s be honest, a machine of this age can present some real head-scratchers in the garage. Finding parts, diagnosing quirky electrical gremlins, or tuning that old-school carb can feel like a daunting task.
I promise this guide will be your go-to resource. We’re going to tear down the myths and give you the confidence to tackle this classic quad. We’ll walk through everything from its unique history and essential maintenance to troubleshooting the most common problems and sourcing those hard-to-find parts. This is your complete 87 polaris trail boss guide to keeping that legend alive and ripping on the trails.
What Makes the 87 Polaris Trail Boss an Enduring Classic?
Before we grab our wrenches, it’s worth understanding why this machine holds a special place in ATV history. The Polaris Trail Boss, first introduced in 1985, was a game-changer. It was one of the first American-made ATVs to seriously compete with the Japanese giants.
The 1987 model, specifically, is a perfect example of this era. It features a robust, air-cooled 250cc two-stroke engine. Unlike modern, complex four-strokes, this powerplant is beautifully simple, making it an ideal machine for the DIY mechanic to learn on.
One of the key benefits of an 87 polaris trail boss is its straightforward design. It sports a chain drive and a Polaris Variable Transmission (PVT), which was revolutionary at the time. This combination delivered reliable, automatic-style performance that was easy for riders of all skill levels to handle. It’s a raw, mechanical experience that modern machines just can’t replicate.
Your Essential 87 Polaris Trail Boss Maintenance Checklist
Consistent maintenance is the absolute key to reliability. A little time in the garage prevents a long walk back from the trail. Think of this as the core of your 87 polaris trail boss care guide. Follow these best practices, and your quad will thank you for it.
Fuel System Fundamentals
The fuel system on a two-stroke is its lifeblood. Old fuel lines and a dirty carburetor are behind 90% of running issues.
- Inspect Fuel Lines: Check all rubber fuel and oil injection lines for cracks, hardening, or mushiness. If they aren’t pliable, replace them immediately with proper fuel-rated hose. A cracked line can cause a lean condition and destroy your engine.
- Clean the Carburetor: The Mikuni slide carburetor is simple but needs to be clean. Use a quality carb cleaner spray and compressed air to meticulously clean the jets (pilot and main), float bowl, and all internal passages.
- Check the Fuel Filter: Always run an in-line fuel filter. It’s cheap insurance. Replace it yearly or if you see debris in the clear housing.
Two-Stroke Engine Care
The heart of your 87 polaris trail boss is that peppy 250cc engine. Keeping it happy is simple but non-negotiable.
- Spark Plug: This is your window into the engine’s health. Pull the plug often. A light, chocolate-brown color is perfect. Black and oily means it’s too rich; white or gray means it’s dangerously lean. Use an NGK B8ES or equivalent and gap it correctly (usually around 0.028″).
- Air Filter: A clean, properly oiled foam air filter is critical. A dirty filter chokes the engine, while a torn one lets in dirt that will score the piston and cylinder wall. Clean it after every few rides with filter cleaner and re-oil with proper foam filter oil.
- Oil Injection System: Verify the oil injection pump is working. You can do this by marking the oil tank level, going for a short ride, and ensuring the level has dropped. Always use a quality 2-stroke injector oil designed for air-cooled engines.
Drivetrain and Brakes
Getting power to the ground and stopping safely are pretty important, right? Don’t neglect these systems.
- Chain and Sprockets: Keep the drive chain clean, lubricated with a quality chain lube, and properly tensioned. There should be about 1/2 to 3/4 inch of slack. Check the sprocket teeth for “hooking” or sharp points, which indicates they are worn and need replacement.
- Brake System: The ’87 model has hydraulic disc brakes, which were advanced for their time. Check the brake fluid level in the master cylinder reservoir. If the fluid is dark or murky, it’s time to bleed the system with fresh DOT 3 brake fluid. Inspect pads for wear and the rotor for deep grooves.
Diagnosing Common Problems with the 87 Polaris Trail Boss
Even with great care, things can go wrong. Here’s a rundown of the most common problems with an 87 polaris trail boss and how to start troubleshooting them. This is how to approach the puzzle when your machine acts up.
“It Won’t Start!” – The Big Three
When an engine won’t fire, it’s almost always one of three things: spark, fuel, or compression. Test them in order.
- Check for Spark: Remove the spark plug, re-attach it to the plug wire, and hold the threaded part against the metal engine cylinder. Pull the starter rope. You should see a strong, blue spark jump the gap. No spark or a weak yellow spark points to a bad plug, coil, or CDI box.
- Confirm Fuel Delivery: Is the spark plug wet with fuel after trying to start it? If not, you have a fuel delivery problem. Check for a clogged fuel filter, pinched line, or a stuck float in the carburetor.
- Test Compression: A two-stroke needs good compression to run. You can rent a compression tester from an auto parts store. A healthy engine should have over 110 PSI. Anything under 100 PSI suggests worn piston rings or cylinder, and it’s time for a top-end rebuild.
Bogging Down or Losing Power
This is a classic two-stroke issue, often related to the carburetor. If the engine bogs when you give it gas, it’s likely a clogged main jet. If it idles poorly but revs okay, check the pilot jet. Also, inspect the rubber intake boot between the carb and engine for cracks, which cause a massive air leak and lean condition.
Another culprit can be a clogged exhaust. The spark arrestor screen in the silencer can get plugged with carbon. Remove it and clean it with a wire brush and some carb cleaner for a quick performance boost.
How to 87 Polaris Trail Boss: Pro Tips for Riding and Upgrades
Once your machine is running right, a few extra 87 polaris trail boss tips can enhance the experience. Knowing how to handle this vintage beast is just as important as knowing how to fix it.
Sourcing Parts for a Vintage Machine
Finding parts can be a treasure hunt. Your local dealer likely won’t have much. Your best bets are:
- eBay Motors: The number one source for both used OEM parts and new-old-stock (NOS).
- Online Forums: Websites like Polaris ATV Forums have dedicated sections for vintage models where members often sell parts.
- Specialty Shops: Places like Dennis Kirk or Parts Pit Stop sometimes have diagrams and part numbers that can cross-reference to available components.
Simple, Effective Performance Mods
You don’t need to go crazy to wake up the 250cc engine. The best mods focus on helping it breathe better.
A quality aftermarket expansion chamber and silencer (like from DG Performance or FMF) combined with a carburetor re-jetting can make a huge difference. You can also install a clutch kit with different springs and weights to change how the PVT engages, giving you better low-end torque for trails or more top-end for open fields.
The Sustainable 87 Polaris Trail Boss: Longevity and Responsible Riding
You might not think of a two-stroke as “eco-friendly,” but the most sustainable practice is keeping a perfectly good machine out of the landfill. Embracing a repair-not-replace mindset is the core of being a sustainable 87 polaris trail boss owner.
By rebuilding the carburetor instead of buying a cheap knock-off, or by sourcing a good used OEM part, you reduce waste. This approach is not only better for the environment but also often results in a more reliable machine, as original parts are typically higher quality.
Furthermore, being an eco-friendly 87 polaris trail boss rider means being responsible on the trails. Use modern, high-quality, low-smoke 2-stroke oils to reduce emissions. And always follow the principles of Tread Lightly: stay on designated trails, pack out everything you pack in, and respect the wilderness you’re there to enjoy.
Frequently Asked Questions About the 87 Polaris Trail Boss
What kind of oil should I use in my 87 Trail Boss?
For the engine, use a high-quality air-cooled 2-stroke injector oil. Do not use TC-W3 marine oil. For the transmission/gearcase, a dedicated chaincase lubricant like Polaris AGL is recommended, but a quality 75W-90 gear oil can work in a pinch.
Is the 87 Trail Boss a good beginner ATV?
Yes and no. Its automatic-style PVT transmission makes it easy to ride. However, its age means it requires more mechanical attention than a modern ATV. It’s an excellent machine for a beginner who wants to learn how to wrench.
How can I find the VIN on my 87 Polaris Trail Boss?
The Vehicle Identification Number (VIN) is typically stamped on the front left frame rail, down low near the A-arm mount or footwell. It may be covered in dirt or paint, so you might need a wire brush to reveal it.
What is the top speed of a stock 87 Trail Boss?
A stock 87 polaris trail boss in good running condition will typically have a top speed of around 45-50 MPH, depending on rider weight and conditions. Its strength is its peppy acceleration, not its outright top speed.
Owning a classic quad like the 87 polaris trail boss is a rewarding journey. It’s a machine that teaches you, challenges you, and connects you to the pure, simple fun of off-roading. It demands respect and consistent attention, but the payoff is a reliable, fun-to-ride piece of ATV history.
So get out in the garage, get your hands dirty, and use this guide to keep that two-stroke legend alive for another generation of trail riding. Stay safe, have fun, and happy wrenching!
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