Though the Yamaha Big Bear 400 is a few clicks shy from being a big-bore quad, it remains one of the most reliable, durable, and satisfactory ATVs in the market. Thanks in part to its impressive off-road and multifunctional features, the quad’s entry-level design makes it a sought-after four-wheeler.
A larger, more robust successor to the Big Bear 350, this quad has retained some of its precursor’s attributes, both in performance and external features. Nevertheless, the Yamaha Big Bear 400 is no doubt the tougher and more dependable vehicle, considering the modifications that were onto the latter models. Among which are the dual A-arm rear suspension and wet brake systems.
The Big Bear 400 sported a 387-cc, air-cooled engine and had a driveline selector, enabling operators to choose between driving in 2WD or 4WD mode. Moreover, like the 350, theis quad is fitted with a semi-automatic clutch configuration, which contributed to its entry-level design despite being on the weighty side.
This off-roader does a superb job in conquering any terrain. Whether they’re dirt tracks, mud holes, hard packs, rocky trails, and even water crossings, this quad can get you from origin to destination. For that matter, many owners see the Yamaha Big Bear 400 as an excellent trail quad and hunting rig. Apart from that, this vehicle makes an excellent pack mule and farm grunt. To top it all off, this all-terrain workhorse is one of the most cost-effective of its type. And that’s what makes the Big Bear stand out if placed alongside other ATV heavyweights.
With that said, it’s clear why the 400 enjoyed a lengthy production run, just like its Big Bear sibling. Since this quad has remained consistent with its dependability and performance, it’s certain the Yamaha Big Bear 400 is there to stay as one of the popular and premier ATVs to grace Yamaha’s production line.
What Are the Different Models of the Yamaha Big Bear 400?
First released in 2000, the Yamaha Big Bear 400 lived up to consumer’s expectations as a high-quality, multipurpose work quad. With its convenient, push-button drivetrain selector, operators can choose between this workhorse’s three-way interlocking differential. For that reason, owners enjoy driving in either 2WD, 4WD, or locked 4WD drive shaft modes. This feature is one of the many reasons the Yamaha Big Bear 400 had a substantial following, particularly in the hunting and farming community.
Overall, Yamaha was diligent in manufacturing numerous models and trims of the Big Bear 400. Among these models were the Hunter Edition models, which had different model years with Realtree camo finish. This trim targeted the outdoorsy and working class types, particularly hunting enthusiasts.
The table below consists of the different models of the 2WD Yamaha Big Bear 400. These base models were only produced from 2000 to 2004.
| Year — 2WD (Base) | Model |
| 2000 — Yamaha Big Bear 400 2WD | YFM400M |
| 2001 — Yamaha Big Bear 400 2WD | YFM400MC |
| 2002 — Yamaha Big Bear 400 2WD | YFM400N |
| 2003 — Yamaha Big Bear 400 2WD | YFM400P |
| 2004 — Yamaha Big Bear 400 2WD | YFM40S |
Yamaha remained consistent in its production of the 4WD Big Bear 400. The table below mentions the different 4WD base models, which began from 2000 to 2012.
| Year — 4WD (Base) | Model |
| 2000 — Yamaha Big Bear 400 4WD | YFM400FM |
| 2000 — Yamaha Big Bear 400 4WD | YFM400FMC |
| 2001 — Yamaha Big Bear 400 4WD | YFM400FN |
| 2002 — Yamaha Big Bear 400 4WD | YFM400FP |
| 2003 — Yamaha Big Bear 400 4WD | YFM400FWR |
| 2004 — Yamaha Big Bear 400 4WD | YFM40FS |
| 2005 — Yamaha Big Bear 400 4WD | YFM40FT |
| 2006 — Yamaha Big Bear 400 4WD | YFM40FV |
| 2007 — Yamaha Big Bear 400 4WD IRS | YFM40FBW |
| 2008 — Yamaha Big Bear 400 4WD | YFM40FBXGR |
| 2008 — Yamaha Big Bear 400 4WD | YFM40FBXL |
| 2008 — Yamaha Big Bear 400 4WD | YFM40FBXR |
| 2009 — Yamaha Big Bear 400 4WD | YFM40FBYB |
| 2009 — Yamaha Big Bear 400 4WD | YFM40FBYGR |
| 2009 — Yamaha Big Bear 400 4WD | YFM40FBYL |
| 2010 — Yamaha Big Bear 400 4WD | YFM40FBZGR |
| 2010 — Yamaha Big Bear 400 4WD | YFM40FBZL |
| 2011 — Yamaha Big Bear 400 4WD | YFM40FBAGR |
| 2011 — Yamaha Big Bear 400 4WD | YFM40FBAL |
| 2012 — Yamaha Big Bear 400 4WD | YFM40FBBGR |
| 2012 — Yamaha Big Bear 400 4WD | YFM40FBBL |
Targeting the Hunters
Designed and produced in Yamaha’s Georgia-based factory in Newnam, the Buckmaster had a liquid-cooled engine. This feature, which was different from the air-cooled base Big Bear 400 models, enabled this four-wheeler to operate optimally even under low engine conditions. Also, the additional oil also kept the Buckmaster’s mechanical parts well-lubricated.
As a liquid-cooled ATV, the Buckmaster had the oil coolant high up in its frame. This layout helped prevent clogging or damage to the radiator, especially when traversing shallow waters or mud holes. This trim had a similar driveline selection system as the other Big Bear 400 base models.
Likewise, the Hunter variants that Yamaha started manufacturing in 2007 were oil-cooled, two-way driveline options, and a camo finish. The awesome feature about the Hunter trim is the quad’s independent rear suspension (IRS) design, which provided easier steering capability and a tighter turning radius.
| Year — Buckmaster/Hunter Trims | Models |
| 2000 — Yamaha Big Bear 400 4WD Buckmaster | YFM400FHM |
| 2007 — Yamaha Big Bear 400 4WD Hunter IRS | YFM40FBHW |
| 2008 — Yamaha Big Bear 400 4WD Hunter | YFM40FBHX |
| 2008 — Yamaha Big Bear 400 4WD Hunter | YFM40FBX-B |
| 2009 — Yamaha Big Bear 400 4WD Hunter | YFM40FBHY |
| 2010 — Yamaha Big Bear 400 4WD Hunter | YFM40FBHZ |
| 2011 — Yamaha Big Bear 400 4WD Hunter | YFM40FBHA |
| 2012 — Yamaha Big Bear 400 4WD Hunter | YFM40FBHB |
The trims with the Realtree finish were released from 2001 to 2002. These variants came in both 2WD and 4WD versions, with the latter classified as the Realtree X-Tra.
| Year — Realtree Trims (2WD and 4WD) | Models |
| 2001 — Yamaha Big Bear 400 2WD Realtree | YFM400HN |
| 2001 — Yamaha Big Bear 400 4WD Realtree X-Tra | YFM400FHN |
| 2002 — Yamaha Big Bear 400 2WD Realtree | YFM400HP |
| 2002 — Yamaha Big Bear 400 4WD Realtree X-Tra | YFM400FHP |
Apart from these trims, Yamaha also produced an Exploring Edition and Hardwoods model in 2007. This former variant came with a front rack vinyl storage and a rear rack with rails. This vehicle had the same features as the Buckmaster and Hunter versions.
| Year — Exploring Edition / Hardwoods Trims | Model |
| 2007 Yamaha Big Bear 400 4WD IRS Exploring Edition | YFM40FBEW |
| 2007 Yamaha Big Bear 400 4WD IRS | YFM40FBW-B |
What Is the Cost of a Yamaha Big Bear 400?
The suggested list cost of the Yamaha Big Bear 400 4WD varies depending on the year of the model. A 2000 2WD model fetches around $4,599, with a retail value that ranges between $820 to $`1080, according to www.nadaguides.com.
The same can be said of the various trims in the 400 lineup. The 2010 Big Bear 400 Hunter model (YFM40FBHZ ) costs around $6,649, and has a $300 price difference with the 2012 variant (YFM40FBH). Both have a retail cost that ranges anywhere from $2,900 to $4,700.
On the other hand, the 2010 to 2012 models are cheaper by $300 to $400 compared to their Hunter counterparts. These units, according to www.atv.com and www.nadaguides.com, fetch around $6,299 (2010) and $6,599 (2011 and 2012).
The table below provides the current suggested list values of the 2000 to 2009 4WD models, including their low and average retail costs. The numbers mentioned are based on www.nadaguides.com.
| Year — Model | Suggested List Value | Low / Average Retail Value |
| 2000 Yamaha Big Bear 400 4WD — YFM400FM | $5,399 | $985 / $1,295 |
| 2001 Yamaha Big Bear 400 4WD — YFM400FN | $5,399 | $1,025 / $1,350 |
| 2002 Yamaha Big Bear 400 4WD — YFM400FP | $5,199 | $1,130 / $1,485 |
| 2003 Yamaha Big Bear 400 4WD — YFM400FWR | $5,199 | $1,125 / $1,480 |
| 2004 Yamaha Big Bear 400 4WD — YFM40FS | $5,199 | $1,175 / $1,545 |
| 2005 Yamaha Big Bear 400 4WD — YFM40FT | $5,199 | $1,275 / $1,675 |
| 2006 Yamaha Big Bear 400 4WD — YFM40FV | $5,199 | $1,565 / $2,060 |
| 2007 Yamaha Big Bear 400 4WD — YFM40FBW | $5,599 | $1,740 / $2,290 |
| 2008 Yamaha Big Bear 400 4WD — YFM40FBXR | $5,599 | $1,775 / $2,335 |
| 2009 Yamaha Big Bear 400 4WD — YFM40FBYB | $6,099 | $2,150 / $2,830 |
Specifications and other Technical Features of the Yamaha Big Bear 400
Engine
The Yamaha Big Bear 400 has an air-cooled, four-stroke, single-cylinder engine with a single overhead cam (SOHC) configuration and a displacement of 387 cc. The bore measures at 83 millimetres (3.27 inches), while the stroke is 71.5 millimetres (2.81 inches). It has a 33-millimetre (1.30 inches) BS33 Mikuni delivers the proper fuel-air mixture, enabling this machine to produce a compression ratio of 8.6:1.
Fuel
This four-wheeler uses unleaded gasoline with a pump octane number (PON) 86 and up or research octane number (RON) of 91 and up. Using premium unleaded gasoline is also advisable in case knocking or pinging occurs. The Yamaha Big Bear 400 has a fuel capacity of 15 litres (3.96 US gal) and a reserve tank of 4 litres (1.06 US gal).
Regarding the use of gasohol, you may use gasoline with no more than 10% ethanol as fuel. However, the manufacturer discourages using methanol, regardless of the percent content as this could lead to serious engine damage or poor performance.
Lubrication
The quad requires the Yamalube 4 with viscosity ranging from SAE 5W30, SAE 10W30 to SAE 20W40, depending on the outdoor temperature. The engine oil grade should be of JASO MA standard and should have an API service of SG or higher. The oil capacity for the Yamaha Big Bear 400 without filter replacement is 2.9 litres (3.07 US quarts), while 3 litres (3.17 US quarts) if filter replacement is necessary.
Ignition
A direct current-capacitor discharge ignition (DC-CDI) system brings this 400-cc utility ATV to life. Alternatively, a mechanical recoil also starts the Big Bear’s machine and may serve as backup. The AC magneto generator brings power to the quad’s electrical components, such as the headlights and other accessories.
The Yamaha Big Bear 400 uses an NGK DR8EA spark plug with a gap of 0.6 – 0.7 millimetres (0.024 – 0.028 inches). Additionally, this vehicle requires a YTX20L-BS type battery with a 12-volt, 18-Ah capacity.
Transmission/Drivetrain
As a semi-automatic quad, the The Yamaha Big bear 400 has a forward five-speed, constant-mesh and a wet-type transmission clutch system, with the inclusion of a reverse gear. A push-button On-Command 4WD driveline selector enables the operator to drive either in 2WD, 4WD, or 4WD locked differential mode with ease.
Moreover, this ATV uses a spur gear and a shaft drive for its primary and secondary reduction systems, respectively. The stock Big Bear has a primary reduction ratio of 76/24 ((3.167) and the secondary reduction ratio is 28/24 × 24/18 × 33/09 (5.704). The gear ratios of this vehicle are as follows:
| Gear | Ratio Values |
| 1st Gear | 40/12 (3.333) |
| 2nd Gear | 34/18 (1.889) |
| 3rd Gear | 30/22 (1.364) |
| 4th Gear | 25/26 (0.962) |
| 5th Gear | 19/27 (0.704) |
| Reverse Gear | 22/17 × 35/15 (3.020) |
Suspension
A 2007 Yamaha Big Bear 400 4WD IRS has an independent double-wishbone front and rear suspension systems. This feature provides the ATV with better steering capability and a tighter turning radius of 3,200 millimetres (126 inches or 10.3 feet), improving the quad’s manoeuvrability.
Both the front and rear suspensions have fork preload adjustments and have a wheel travel of 149.9 millimetres (5.9 inches). Furthermore, the Big Bear is fitted with dual rear shocks which ensures a smoother ride regardless of the terrain.
Brakes
This four-wheeler has a dual hydraulic disc front brake and a five-disc, oil-bathed rear brake, which provides better stopping power both in land and water. The front brake is operated using the right-hand lever. On the other hand, the rear brake can be operated either with the left-hand lever or the right-foot pedal. The DOT 4 is the recommended fluid for the Big Bear 400’s braking system.
Tyres
Though the brands of tyre differ from the year model of this ATV, the stock 2007 model is fitted with a set of tubeless ITP/Mud Lite tyres. The front tyres have a size of AT25 x 8 -12 while AT25 x 10 – 12 on the rear.
The recommended tyre pressure for both front and rear tyres are 25.0 kPa (3.6 PSI; 0.250 kgf/cm²) and 25.0 kPa (3.6 PSI; 0.250 kgf/cm²), respectively. Likewise, the minimum tyre pressure should not exceed 22.0 kPa (3.2 PSI; 0.220 kgf/cm²), and the maximum should be no more than 250 kPa (36 PSI; 2.5 kgf/cm²). These figures apply to both the front and rear tyres.
Dimensions
The Yamaha Big Bear 400 is 2,016 millimetres (79.4 inches) in length, 1,116 millimetres (43.9 inches) in width, and 1,187 millimetres (46.7 inches) in height. The quad has a seat height of 895 millimetres (35.2 inches), a ground clearance of 267 millimetres (10.5 inches), and a wheelbase of 1230 millimetres (48.4 inches). With a dry weight of 252.2 kilograms (556 lbs), this four-wheeler’s curb weight reaches up to 285 kilograms (628 lbs) once filled with gas and oil.
Capacity
This workhorse has a towing capacity of 410 kilograms (904 lbs). The front and rear carriers can hold up to 40 kilograms (88 lbs) and 80 kilograms (176 lbs) of weight. A storage compartment located at the rear of the vehicle has a load limit of no more than 2 kilograms (4 lbs).
External Features
The Big Bear 400 comes with a steel tube frame-type chassis with a trail width of 17 millimetres (0.67 inches) and a 3-degree caster angle. The ATV’s body is made of quality, durable plastic material.
Bone stock, the 400 comes complete with standard hand grips, floor boards, foot pegs, brush guard, and CV boot covers. This quad is also fitted with front and rear fenders and bash plates, as well as a brush guard. Since this is the Big Bear for the outdoorsy types, it also comes with a front bumper and a pair of front A-arm skid plates for added protection from rocks, twigs, and the sort.
The handlebar serves as the Big Bear 400’s steering system, where perched on top at the centre is the instrument cluster, namely: trip odometer, fuel gauge, and speedometer. Also included are the reverse and neutral gear indicators. The On-Command push-button 4WD selector is located on the right handlebar, along with the throttle.
Among the quad’s electrical components are the dual 12-volt, 30-watt Krypton, 12-volt, 5/21-watt tail lights. Moreover, all the indicator lights use 12-volt, 1.7-watt bulbs each.
What is the Top Speed of the Yamaha Big Bear 400?
The Yamaha Big Bear 400 runs at an average top speed of 45 MPH. However, some owners have reported to have gone 52 MPH even on stock components. Despite this, you will be wise to note that this four-wheeler is far from being a racer class. This is a trade-off in most utility quads, like Honda’s workaholic machines, the Recon and the Foreman.
45 Going 50 — Improving the Top Speed of the Yamaha Big Bear 400
Replacing the drive gears could help improve the speed of your YFM400. Unfortunately, similar to the FourTrax, the Big Bear 400 uses a drive shaft. Therefore, changing the sprockets would be out of the question.
If you’re eager to pull this through, you might want to take note of a few basic components, like a quality air filter, mod up the airbox, and use an aftermarket performance exhaust. Often, this setup requires carb rejetting, since you have a better air intake. Otherwise, your workhorse-turned-speed beast won’t get the power it needs.
Apart from this, you may also replace those stock 25-inch tyres with something taller, such as a 26- or 28-incher. To keep those tall tyres from scraping against the fender or exhaust, you may want to install a lift kit. This mod, along with the air filter and carb rejetting may considerably improve the top speed by 60 MPH.
Though this mod may provide your Big Bear that much-needed top speed, you may lose the advantage of traversing mud holes with ease, which is what these 4WD YFM400’s are known for. Bigger tyres are generally on the heavy side, so this setup can take away some of those HP juice. Regardless, if you are still keen on taking your upgraded Big Bear on a dip, installing a snorkel to keep water off the air filter would be a wise choice.
A Better, More Reliable Big Bear
The Yamaha Big Bear 400 is an impressive machine, thanks to its topnotch design and optimal off-road features. With that said, the YFM400 4WD is indeed a consumer-oriented utility ATV, with none of that fluff, and more of the quality and toughness needed to get the hard work done and for a smooth comfortable ride.
Since its specs weren’t different from its 350-cc sibling, one can’t help but think that Yamaha had somehow overdid the YFM400 for the sake of redeeming the Big Bear lineup. In which case, we appreciate all of this, considering its overall performance as a hardworking grunt. For that matter, we want to highlight some of the features that make this ATV one of the best utility quads in the market.
Oil-Bathed Rear Brakes
Unlike the typical hydraulic drum brakes often seen in mudders like the Recon, the wet-type braking system is an innovative approach for a utility ATV. This design keeps the entire braking system safe from immediate wear caused by mud, silt, and water, and provides better stopping power. There’s no doubt that the Big Bear 400 was made not just as an effective workhorse, but also as a thrilling trail quad.
IRS
Yamaha really cranked up the notch on the Big Bear 400 when they decided to put the independent rear suspension (IRS) on the quad. This feature turned this four-wheeler into the ultimate off-road vehicle. In fact, owners have attested that the Big Bear offered a stabler, smoother ride whether they’re traversing mud bogs, and water crossings. Coupled with a higher ground clearance and adjustable preload shocks, this quad also performs well on extremely rocky surfaces and other technical terrain.
About the Manufacturer
Apart from motorcycles and automotive engines, Yamaha Motor Company Ltd. is known for manufacturing and developing innovative products. Among these items are unmanned aerial engines, commercial and recreational vehicles, power-assisted bikes, and even high-performance industrial robots. The Yamaha Big Bear 400 4WD is one of the many products that the company has produced for both enthusiasts and consumers alike. Based in Iwata, Shizuoka, this Japanese company continues to inspire people by their practice of the Kando philosophy, which entails bringing joy and fulfilment through the products they create.
Final Takeaway — Yamaha Big Bear 400
The Yamaha Big Bear 400 is a combination of unique and novel features that bought out the best in this quad. For the 2007 trim, for instance, the On-Command 4WD driveline selector compliments this vehicle’s off-road capability, including the location of its oil-cooling system, among others.
All in all, the Big Bear’s towing capacity and overall reliability and manoeuvrability made this ATV a big name among hardworking folks, like farmers and ranchers. Plus, with its entry-level design and revolutionary features, there’s no reason why you shouldn’t own this purpose-built quad. For us, it’s definitely worth it.
