The Yamaha Big Bear 400 was a tough and reliable quad that could get the job done. Its superior power was a perfect trade-off for top-end speed, and its rugged appeal, towing capabilities, and mighty engine were a big hit with consumers. People adored this wheeler, even with its imperfections.
Often compared to a Fourtrax 300 and confused with a Wolverine, the Yamaha Big Bear 400 made itself quite a following during its 12-year production run. Sporting a mid-size chassis, dual driveline modes, smooth transmission, and a powerful engine, the Big Bear was a breakthrough for Yamaha.
The quad remained true to Yamaha’s reputation of producing reliable and durable vehicles until the very end – so much so that a lot of Yamaha enthusiasts were saddened by the discontinuation of the model in 2012. This read will enlighten you on why the Big Bear is so well-loved by consumers, as you learn about its specs and features, highs and lows, and more.
The Revolutionary 4×4
The Yamaha Big Bear 400 is the 17th model released by Yamaha since its 1980 Tri-Moto launched in the U.S. The Yamaha Big Bear 400 was initially designed for work and carried the same terminology as its 1987 350-class predecessor. It was not the first ATV to have 4×4 specifications, but it offset it by being the first with fully camouflaged bodywork, making it popular as a hunting vehicle. The four-wheeler was produced from 2000 to 2012 before it ceased production to develop the rest of Yamaha’s ATV lineup.
Yamaha got busy during the Big Bear’s production run, creating several different trims across all model years:
Yamaha Big Bear Trims
- 2000 Yamaha Big Bear 400
- YFM400FWNM-FWNMC-FWNHM (4WD Buckmaster)
- YFM400M-NMC (2WD 4WD)
- 2001 Yamaha Big Bear 400
- YFM400FHN-FN (4WD Hunter)
- YFM400HN-N (2WD Realtree)
- 2002 Yamaha Big Bear 400
- YFM400P-HP (2X4 Hunter)
- YFM400FP (4X4)
- 2003 Yamaha Big Bear 400
- YFM400FWR (4X4)
- YFM400NR (400 2WD)
- 2004 Yamaha Big Bear 400 (YFM40S 2WD)
- 2004 Yamaha Big Bear 400 (YFM40FS 4X4)
- 2005 Yamaha Big Bear 400 (YFM40FT 4X4)
- 2006 Yamaha Big Bear 400 (YFM40FV 4X4)
- 2007 Yamaha Big Bear 400
- YFM40FBEW-FBHW-FBW (4WD Hunter IRS Exploring Edition)
- 2008 Yamaha Big Bear 400
- YFM400FBHX-FBXGR-FBXL-FBXR 4WD
- 2009 Yamaha Big Bear 400 (FM400FB 4WD)
- 2010 Yamaha Big Bear 400 (YFM400FB 4WD)
- 2011 Yamaha Big Bear 400
- YFM400FBAGR-FBAL-FBHA Big Bear 4WD
- 2012 Yamaha Big Bear 400 (YFM400FB 4WD)
If there is anything that best signifies the carrier name of this model, it is the engine. The power mill of this quad is comparable to a V8 fitted into a mid-size 4×4. It has a dirt bike-style BSR33 carb, a 4-gallon gas tank, a large oil-cooler, and a CDI ignition. On the outside, the quad’s flexible plastic fenders are indestructible, easy to clean and offer adequate splash protection. Front and rear bumpers protect the mechanical components, and racks provide plenty of cargo space. Electronics and fuses are under the seat, along with the airbox and battery.
2000 Yamaha Big Bear 400 Specs (YFM400FNM)
- Engine – It is powered by a four-stroke, air-cooled, single-cylinder SOHC engine. The forward-inclined power mill has a bore-stroke ratio of 83 × 71.5 millimeters (3.27 × 2.82 inches). The Yamaha Big Bear 400 4×4 has an engine displacement of 386 cubic centimeters, a compression ratio of 8.6:1, and a wet sump lubrication system. A 33-mm Mikuni BSR carburetor handles the air-fuel mixture. Fuel tank capacity is 3.96 US gallons/15 liters, with 1.06 US gallons/4 liters reserve.
- Drivetrain – Power travels via a constant-mesh, five-speed centrifugal wet type automatic transmission (inclusive of a reverse gear). It has a primary spur gear and a secondary shaft drive system that is left foot operated. A super-low first gear enables the quad to tackle the toughest chores and trails. On-Command In/Out 4WD is available on the 2012 Yamaha Big Bear 400, which lets you switch between 2WD/4WD and full-lock differential 4WD with push-button ease.
- Ignition – It is started by a DC-CDI electric start system with an auxiliary recoil mechanical backup that helps minimize slippage. It also has an AC-magneto generator system and requires a 12V, 18 Ah battery.
- Tires – Dunlop KT404 AT25 X 8-12 front tires and Dunlop KT4058 AT25 X 10-12 rear tires mount on tubeless steel wheels. The recommended tire pressure is 3.6 psi/25 kPa (0.25 kgf/cm²). Do not go beyond tire pressure limits of 3.2 psi/22kPa (0.22 kgf/cm²) and 36 psi/250 kPa (2.5 kgf/cm²).
- Brakes – Front dual hydraulic disc brakes and a sealed mechanical drum at the rear provide the Big Bear stopping power.
- Suspension – The quad features an independent double-wishbone front and swing arm rear suspension with five-way preload-adjustable shocks for both that allow 5.9 inches of wheel travel. The 2004 Yamaha Big Bear 400 had high-quality Showa spring/shocks front and rear. For all models, the vehicle’s IRS provides maximum ground clearance and excellent maneuverability on diverse terrain.
- Dimensions – The quad’s overall dimensions are 79 x 43.7 x 46.1 inches (2,007 x 1,111 x 1,172 millimeters – L x W x H). The minimum ground clearance is 9.65 inches, while the minimum turning radius is 124 inches. The vehicle wheelbase is 48.4 inches. Curb weight is 266 Kg/586 lbs. Towing capacity is 904 lbs/410 Kg, plus 265 lbs/120.2 Kg combined rack capacity.
- Exterior – It is made up of a steel tube frame (with a 4° caster angle and 21-mm trail) and plastic body material. The full floorboard is on the driver’s side. The wheeler comes with standard handgrips, fenders, front A-arm skid plate, and front/rear bash plates. Instrumentation consists of a trip odometer, speedometer, and temperature/fuel indicators, and you will find 88 lbs/39.9 Kg worth of extra storage under the seat.
The Yamaha Big Bear 400 had 30 trims during its 12-year production run based on online references and research.
What Big Bear Owners Love About Their Quad
Big Bear owners have a thing or two that they love about the vehicle. For some, it is the auto clutch manual shift and five-speed transmission. For rock crawlers, it is the super low first gear. It is the absence of a CVT belt (according to them, these belts require more to maintain). And for the working John, it is the wheeler’s mid-range power and towing capacity.
Riders appreciate missing out on having a turbo lag when letting off and quickly getting back on the throttle. Farmers marvel at the quad’s ability to pull 12-foot logs with no difficulty. People who have bought the vehicle say that they made a great choice in choosing the Big Bear over the Wolverine, and most prefer the manual-shift transmissions over the more recent trims that came out.
Yamaha Big Bear 400 Top Speed
The Big Bear top speed is 52 mph on stock – but only averages up to 45 mph for most owners. While the quad is meant for hard work and low-end grunt, there are a few Yamaha Big Bear 400 parts that you can upgrade to improve its top-end speed and power delivery and its look and off-road readiness. Here are a few of them:
- New rims and taller tires
- 2-inch bracket lift
- Snorkel kit and new fuel lines (great for water crossing and mud holes)
- LED lights to replace the Krypton bulbs
- HMF Performance exhaust
- Bigger main jet in the carburetor for more power
- Full belly steel skid plates and A-arm protectors (if you do a lot of rock crawling)
Youtuber Grizzly Greg recommends the Yamaha Big Bear 400 for those looking for a great quad but are on a tight budget and shares the upgrades that he did on the four-wheeler in this video:
A word to the wise – performance mods to your engine will not make you hit a top speed of above 60 mph due to the gear ratio on these wheelers – meaning changing the gear ratio is the foremost thing you have to do. If you intend to keep the direct drive shaft and rims stock, the only way to go is to get bigger tires. However, tires bigger than 25″ (stock to mount) are hard to come by – you may end up spending over $750 for custom rims and rubber.
More About the Big Bear
- What fuel should I use for the Yamaha Big Bear 400? You should use regular unleaded gasoline with a pump Octane number of 86+ and a research Octane number of 91 or higher. 4 US gal/15 liters should be enough to fill your tank. Leaded gasoline can be used but only as a last resort. Also, use fuel with less than 10% ethanol and less than 5% methanol, as these variants may damage the fuel system or cause vehicle performance issues.
- What kind of oil does a Yamaha Big Bear 400 take? The Yamaha Big Bear 400 requires 3.7 quarts/3.5 liters of engine oil (disassembled), 3.1 quarts/2.9 liters (without), and 3.2 quarts/3 liters with oil filter replacement. The recommended engine oils are YAMALUBE 4 SAE 5W-30, 10W-30, or 20W-40, and it’s equivalent. API classification should be SG type or higher and should meet the JASO MA standard.
- How do you change the oil on a Yamaha Big Bear 400? Before you start, make sure to have a socket wrench set, an oil catch basin, new oil, and a filter. Once you have these, you will first have to park your ATV on level ground, access the drain plug near the bottom of the oil pan, drain out all the oil, screw a new oil filter in place, fill the machine with the recommended amount of oil, then start your ATV and check that the oil gauge is within the normal range. This video by jfrost77hd will show you how it is done on a 2000 Big Bear:
- Does the Yamaha Big Bear 400 have flaws? For secondhand Big Bear purchases, the wheeler would naturally have washed-out plastics and rusted racks. Aftermarket brake shoes are too small for the rear drum. Furthermore, some Big Bears experience recurring, inexplicable battery drain.
- Where is the VIN on a Yamaha Big Bear 400? The VIN is located on the steering shaft stamped on an aluminum plate. If you cannot find it there, look on the left side of the frame behind the front tires or the lower frame rail beneath the engine.
- What is the Yamaha Big Bear worth? The list prices of the Yamaha Big Bear 400 range from $5,399 to $6,599, depending on model year, trim, and added accessories. Camo-styled trims are the most expensive of the lot. The average retail value is between $1,175 and $4,050 based on Nada Guides pricing. Kelly Blue Book value for a 2001 Yamaha Big Bear 400 is $1,510 when trading in at a dealership.
Yamaha Motor Company Limited is recognized as a world leader in motorsports that has spawned the ATV industry in the ’80s. The Japanese continue to produce a wide array of life-enriching products and services – including motorcycles, off-road vehicles, personal watercraft, speed boats, and outboard motors. Its mission of creating Kando is ever-present in its product offerings and services. At present, Yamaha continues to innovate, excite, inspire confidence, and strengthen ties to expand its offerings worldwide.
Conclusion – Yamaha Big Bear 400
The Yamaha Big Bear 400 is tough as nails and thrives under battlefield conditions. Whether you are on 10,000 feet of elevation, in extremely high or sub-zero temperatures, or on slick or coarse terrain, it never fails to deliver. It may not be a hotshot by today’s standards. But during its time, it was one of the most sophisticated multifunctional four-wheelers on the market. This revolutionary four-wheeler has and continues to earn itself a remarkable reputation.