In response to the buying public’s clamor for flexibility brought about by utility machines, Polaris launched the Polaris 400 Scrambler in 1995. From the get-go, this sport-oriented vehicle became a hit with consumers. It satisfied the whims of both beginner riders who were discovering the joys of the outdoors and experienced enthusiasts who lived and breathed sport.
Among the progenitors of the fastest 4-strokes ever created, the Polaris Scrambler 400 embodied the epitome of sport riding in the 1990s. This sport-utility machine was one endearing vehicle that offered swift power delivery and thrived in difficult situations, allowing for memorable explorations.
The Polaris Scrambler 400 appealed to riders who fancied utility vehicles but did not entirely use them for yard work. But with the advent of stricter emissions standards, 4-stroke engines, and other forthcoming technological advancements, the market soon outgrew the 400-class 4×4 and shifted its interest to the newer Polaris Scrambler 500. That is – until the rise of mud riding in the mid-2000s. The advent of project builds pushed the revival of 2-stroke machines.
What Started It All
During the ’90s, sport riding did not translate to aluminum wheels, titanium coil springs, or monstrous air intake systems found in present-day pure sport ATVs. For many experienced and professional riders, four-wheel-drive sufficed (and was, in fact, a rarity). Having independent rear suspension was a bonus. The important thing was that the vehicle did not tip over when making big jumps or going off-camber.
Such were the qualities of the 1995 Polaris Scrambler 400. Although it had a straight rear axle instead of IRS, it did have True On-Demand™ AWD Drive System that allowed riders to tread safely on slippery surfaces and mud holes without hydroplaning or getting stuck. Paired with snappy power, a low center of gravity, and long-travel suspension, the Scrambler provided a steady, comfortable riding experience.
Through the course of its 8-year production run, the Polaris 400 Scrambler underwent significant improvements. Weight was taken off the vehicle, reducing it to 481 lbs from 519 lbs. Concentric Drive System (CDS) was applied on 1999 trims and up. Polaris added Fox Shox with a remote reservoir (view on Amazon) to the rear suspension and further increased wheel travel from 7.5 to 8.2 inches at the front and from 8.5 to 10.5 inches at the rear for later-year models. These changes not only enhanced the four-wheeler’s already superb handling but also lent to the Polaris Scrambler 400 top speed of 70 mph.
1999 Polaris Scrambler 400 Specs & Features
Power comes from a 2-stroke, single-cylinder, liquid-cooled engine with oil injection. It has a bore-stroke ratio of 83 x 70 mm (3.27 x 2.76 inches), and the engine displacement is 378 cm3, while the compression ratio is 6.9:1 (effective). A Mikuni VM34SS carburetor handles the air-fuel mixture. Fuel tank capacity is 4.0 US gallons/15.1 liters of unleaded gasoline with a minimum PON rating of 87 (oxygenated) or 89 (non-oxygenated). Make sure not to use fuel with an ethanol content of more than 10% to avoid engine damage.
Here is a video by Mid Nebraska Motorsports that demonstrates how to disassemble, clean, and re-assemble a carburetor on a 1996 Polaris Scrambler 400 4×4:
Oil injector capacity is 2 US quarts (1.9 liters) of Polaris Premium TC-W3 2 Stroke Oil or its equivalent. Conversely, the shift selector box requires 1 oz (30 ml) of Polaris 0W/40 Synthetic Engine Lubricant. Any API-certified SJ engine oil that meets manufacturer specifications and JASO T903 MA standards without molybdenum additives will allow optimum engine performance. However, the use of other oil variants may require more frequent oil changes.
An intelligent True On-Demand™ AWD System, activated via an on/off switch located by the right handgrip, complements the automatic Polaris Variable Transmission. This four-wheel-drive system automatically engages both front wheels with full torque when it senses the rear wheels lose traction. A 520 O-Ring drive chain and a Hilliard-type clutch assembly deliver power to the wheels. A side-lever shift (with an F/N/R gearshift pattern) controls wheel spin.
In a video by Dirt Trax TV, presenter AJ Lester talks about slack in the steering system of a 1997 Polaris Scrambler 400 4×4 – a rather common issue with vintage four-wheelers that have been ridden rough and are over five years old. He narrows down the problem to worn tie rods, which could result from a lack of proper greasing and regular cleaning:
The Scrambler has a DC-CDI (Capacitor Discharge Ignition) electric start system with an auxiliary mechanical recoil starter. It has an ignition timing of 23.5° BTDC @ 3,000 RPM ± 1.5, and its charging system is a triple-phase output alternator with a rated output of 150 watts. A 12V, 14 Ah 210-CCA (Cold Cranking Amps) battery with assembled dimensions of 5.28 x 3.54 x 6.54 inches powers the quad. An NGK BR5E spark plug with a gap of 0.028 inches (0.7 mm) and current 14AH-BS battery (view on Amazon) formats will certainly fit all Polaris Scrambler 400 models.
The four-wheeler uses Carlisle® AT489 23 X 7-10 front tires with steel wheels and AT489 22 x 11-10 rear tires. Recommended tire pressure for front tires is 4 psi/27.58 kPa (0.28 kgf/cm²) and 3 psi/20.68 kPa (0.21 kgf/cm²). In case of wear or damage, you can buy same-size replacement tires or go for taller tires and 2-inch (50-mm) 4×156 Wheel Spacers (view on Amazon).
It uses fixed hydraulic floating-caliper front discs and fixed hydraulic, opposed-piston-caliper discs for the rear and auxiliary brakes. ’00 and more recent models use single-lever, all-wheel hydraulic disc brakes, and a hydraulic rear foot brake. As with all other Polaris ATVs, the manufacturer recommends DOT 3 brake fluid when assembling or servicing brakes to prevent swelling of rubber components and contamination.
The Scrambler front suspension uses a MacPherson Strut with 8.2 inches (208.3 mm) of travel and a rear progressive-rate swingarm with thread-adjustable has-charged mono-shock and 8.8 inches (223.5 mm) of travel. The vehicle’s overall length and 48.5-inch wheelbase lend to its turning radius of 5.0 feet (60 inches), allowing for tighter turning and cornering angles.
Overall dimensions are 74.5 x 45.5 x 47 inches (1,892 x 1,156 x 1,194 mm – L x W x H). The quad’s seat height is 33 inches (838 mm), and the minimum ground clearance (unloaded) is 6.5 inches (165 mm). Dry weight is 519 lbs (235.6 Kg); GVWR is 845 lbs (383.3 Kg) – a combination of curb weight, combined rack capacity of 90 lbs (40.8 Kg), cargo, accessories, plus passenger. Towing and tongue weight capacities are 850 lbs (385.5 Kg) and 30 lbs (13.6 Kg), respectively.
Its Gen III type steel frame has a medium gloss black finish, with a plastic body panel available in Fire Red, Blue, and Bright White. Front and rear fenders, a front brush guard, hand grips and handlebars, full floorboards, and two dual-beam Halogen quartz headlights come as standard features. Additional accessories were available at dealerships as optional package inclusions for a brand-new vehicle. For build projects, you can purchase aftermarket Polaris Scrambler 400 parts from online resellers and auto shops.
On-Demand™ AWD/2WD Drive System
This feature is available on Polaris Scrambler 400 4×4 models and activated via a two-position switch found on the right handlebar. It allows the front axles to automatically engage at any time that the back wheels lose traction. The reverse occurs when the rear wheels regain traction. The said feature was among the highlights of Polaris ATVs before the advent of Independent Rear Suspension.
Concentric Drive System
Thanks to the CDS, the rear suspension travel’s full range can apply without compromising power delivery to the rear wheels. This Polaris feature aligns the swingarm’s pivot point with the drive sprocket center, resulting in consistent chain tension, lesser chain wear, and reduced need for chain adjustment or maintenance.
Polaris Scrambler 400 Cost
It can be challenging to find the list price of 1995-1999 Polaris Scrambler 400s online. The earliest model year with an available MSRP is the 1997 model, valued at $5,399. The cheapest of all trims would be the ’01 2×4 model valued at $4,949, while the most expensive would be the ’02 4×4 model, which costs $5,599. Currently, retail value ranges between $150 and $2,999 – pretty well-kept for a 26-year old vehicle. Most units sold come from the Northeast, New England, and Great Lakes regions. The 1999 and 2000 Polaris Scrambler 400 4x4s have the highest resale value out of all versions.
See the below table for a full rundown of all Scrambler 400 models and their prices:
|Model Year & Trim||List Price||Retail/Trade-in|
|1995 Polaris Scrambler 400 4X4||N/A||$150 – $1,105|
|1996 Polaris Scrambler 400 4X4||N/A||$170 – $1,185|
|1997 Polaris Scrambler 400L||$5,399||$190 – $2,499|
|1998 Polaris Scrambler 400||N/A||$225 – $1,500|
|1999 Polaris Scrambler 400 4×4||N/A||$295 – $2,900|
|2000 Polaris Scrambler 400 2×4||N/A||$350 – $2,500|
|2000 Polaris Scrambler 400 4×4||N/A||$390 – $2,999|
|2001 Polaris Scrambler 400 2×4||$4,949||$960 – $1,950|
|2002 Polaris Scrambler 400 2×4||$4,999||$990 – $2,300|
|2002 Polaris Scrambler 400 4×4||$5,599||$990 – $2,643|
Polaris Scrambler 400 Top Speed
The top speed of a Polaris Scrambler 400 can reach 70 mph and quite remarkably outperforms its 500-class siblings. That said, a stock Scrambler 400 can go head to head with a Predator 500 or a Scrambler 500 (and may even surpass a Yamaha Grizzly) – although the difference may not be that substantial. Still, this speed is superior over its higher-displacement counterparts – thanks to the vehicle’s lightness and powerful 2-stroke engine.
Naturally, advanced riders will not be content with this figure and will look for ways to improve the four-wheeler’s top end. For this purpose, I have listed several steps shared by Aaen Performance that will help you achieve a higher speed rating for your Scrambler (should you decide to embark on this project):
Making the Scrambler Race-Worthy
A previous article covered how Jimmy “The Greek” Anagnoustopolous and his Dyno team turned a Polaris Scrambler 500 4×4 into a drag-race champ. With the Scrambler 400, you follow the same principle – that is, equip your quad with a stage-5 kit and a 44-millimeter carburetor that dramatically improves its power output and, consequently, speed. The five stages in this process gradually increase the RPM, max torque, and max horsepower each time. They aim at cylinder efficiency instead of quick power gains. The RPM stays close to stock levels to maintain reliability and avoid crank problems. Best of all, you decide if you want to exhaust all stages.
Torquer & Top-End Pipe
The first step to increasing speed is to improve the powerband from stock level. Without mods, a stock 400 Scrambler power mill has an extensive powerband with a peak of 38 HP @ 5,750 RPM. Fitting your quad with a Torquer Pipe increases its powerband and gives it a strong bottom end performance, resulting in a maximum power output of 43 HP @ 6,250 RPM. Adding a top-end pipe that produces strong midrange power while still providing good bottom-end pull further increases your brute’s power to 48 HP at 6,250 RPM.
Stage 1: Top-End Pipe, Boyesen RAD Valve & 38-mm TMX Carb
The 38-mm TMX flat-slide carburetor enhances throttle response and improves airflow, eliminating the need for an airbox vacuum to build up. In like manner, the Boyesen RAD valve strengthens midrange pull. When both pair with a top-end pipe, you increase your vehicle’s max power to 52.5 HP @ 6,500 RPM.
Stage 2: Trail Porting
Getting a performance exhaust attached to a 4×4 is the most common route owners take to free up the airflow and improve power output. But for more experienced, skilled owners and mechanics, porting the cylinder head does the trick better. Essentially, porting improves overall flow and changes the RPMs at which your engine starts pulling hard. Note that different types of ports are available – trail, MX, dune, and drag, to name a few. The kind of port you opt for depends on how aggressive or mild you want the change to be and whether you are willing to gain top-end or all-out power at the expense of your midrange or bottom end. At any rate, going for trail porting to the top-end pipe, Boyesen RAD valve, and 38 TMX flat-slide carb will increase your output to 57 HP at 6,750 RPM.
You can get any porting you want, even combination ports like an MX-dune port or a mild drag port. You can be as aggressive or as mild with the changes you want to take effect in your quad, although the former is not advisable. But before deciding, keep in mind the type of exhaust pipe you have dictates what porting you can choose. Simply put, you need to match the porting to your pipe. It would be detrimental to use a drag port with a Pro Circuit Pipe (view on Amazon) or a shearer pipe with an MX port. Furthermore, mismatching the pipes and port work leads to power loss and unpredictable RPMs.
Stage 3: Modified Top-End Pipe, V-Force Reeds & 42-mm TMX Carb
If you already completed the first two stages and are still unsatisfied with the speed of your Scrambler, then fitting your wheeler with a full mod kit is a must. It is essentially a bumped-up version of stage one of this entire process. It consists of the following:
- A modified top-end pipe
- Aftermarket reed blocks that increase throttle responsiveness and enhance engine performance (not to mention works excellently with ported cylinders, big-bore kits, and high-revving racing machines)
- A larger flat-slide TMX carburetor
But instead of trail porting that provides little to no impact on RPMs, these upgrades are mated with race porting, which will bring power output to 61 HP @ 7,250 RPM. You can try this if you are skilled enough. Otherwise, you may need to employ the services of a professional racing outfit.
Stage 4: 440 Big-Bore Kit & More Porting
Big-bore kits usually give you a gain of 10 HP. But given the number of modifications you have completed at this time, this penultimate stage may only increase your ponies to 63 HP. But on the positive side, it results in a large improvement in torque through your vehicle’s powerband. The bore is upgraded from 83 mm to 87 mm and fitted with a custom-made Wiseco forged piston. The ported cylinder and machined head also come with gaskets.
Stage 5: Improved Compression Ratio, Monster Reed Cage & 44-mm TMX Carb
The final steps to improving your Scrambler’s power output is the following:
- Finish your big-bore kit with race porting
- Increase your quad’s compression ratio to 14:1
- Get a Monster Reed Cage
- Increase the carb size
- Get a top-end race pipe
Just make sure that when you increase the compression ratio, you do not overdo it to the point of becoming disadvantageous to the engine. Among the adverse effects of a miscalculated compression ratio are excessive combustion noise and engine wear.
Taking the fuel limit into account, the ideal compression ratio for your Polaris Scrambler 400 would be 10:1, and the maximum would be 11:1. A 12:1 ratio would work perfectly with a 440 big-bore kit but could be a stretch for your vehicle’s powerplant. This final stage delivers 75 HP @ 8,000 RPM, which aptly supports hard acceleration and translates to increased speed when done correctly. Adding 7 mph to your top-end of 70 mph would be a conservative estimate after accomplishing all these steps.
Note that these five stages were initially meant for racing machines and are typically done by professional outfitters. If you intend to use your quad for drag races, complete all these steps (provided that you’re willing to spend $2,800 or more). But if you just want your four-wheeler to have a sportier feel without exactly compromising midrange and bottom-end pull, then the first two to three stages would be more than enough to transform your Scrambler into a speedster.
Polaris Inc. (formerly known as Polaris Industries) is the maker of Polaris Scrambler 400. This American firm is globally known for introducing consumers to revolutionary concepts such as automatic transmission, Independent Rear Suspension (IRS), and Electronic Fuel Injection (EFI). Polaris traces back its humble beginnings to producing farm equipment before releasing the Sno Traveler in 1956 and venturing into the world of all-terrain vehicles in 1985. Its wide array of product offerings continue to mirror its vision.
Conclusion – Polaris Scrambler 400 Review
Despite its simplistic design and conservative features, the Polaris Scrambler 400 possess redeeming qualities that cannot be easily overshadowed. It is among the first to pioneer long-travel suspension and get riders through slop and mud holes years before mud riding became popular. And would you know it – these same attributes gave birth to the highly-lauded big-bore Scramblers of the past decade.
To the public, this 4×4 is known to pave the way for present-day behemoths. In the eyes of skilled mechanics, this sport quad is a joy to customize and makes for a gratifying build project. But for enthusiasts and owners, the Scrambler 400 continues to be one versatile machine that allows them to traverse the unthinkable.