FST 840cc Brute Force
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01-11-2006, 12:43 PM
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FST 840cc Brute Force
From the February Dirt Wheels...
The cc war is on. From the manufacturers to hop-up shops to race teams, everyone is trying to build the biggest ATV motors around. The latest entry into this war is from none other than Four Stroke Tech (FST). FST is one of many engine companies who use their race teams to test and develop products they sell to the public. Their latest creation raises the bar to the 840cc mark. The machine we tested, a Kawasaki Brute Force 750, is one of the fastest in stock trim, so adding almost 100cc made it a monster.
Why
Aside from racers, there are a growing number of customers, primarily from the southern U.S., who need all the power they can get. These guys are the mud runners. Equipped with six-inch lifts and 30-inch tires, this breed of ATVers lives for riding in the deep gumbo mud found in that region. The mud robs power. But unlike the power hungry sand-duners of the west, these guys don't mind the weight of a big utility machine. In fact, utility four wheelers are the vehicles of choice down there. Plus they can easily haul a cooler full of beverages needed for a day of riding. To develop the huge 840cc racer, FST started with a stock 2005 Brute Force 750. The hop-up kits FST sells will fit on any size Prairie, V-Force or Brute Force model. The unique feature of this machine is its camouflage color. Most race quads we feature have bright colors, but this machine really does stand out. At least at the races, that is. Another unique item found on the racer is a small Ramsey winch. Even though the winch may add extra weight, in mud bog events and in some cases for cross-country racing, they are a necessity.
840cc's
To expand the Brute Force's engine to the 840cc mark, FST uses one of their easy to install big bore kits. The kit includes Nik-A-Sil cylinders($460) and two 90mm(stock is 85mm), 11:1 Wiseco pistons(stock is 8:1) ($390). To match the bigger cylinders, FST does a port job on the head ($600), welds the rocker arms($260), installs new valve springs($190), new longer duration cams($400) and Cometic gaskets($60). With the increased engine size , FST had to find an airflow combo that optimized the compression and was adequate for fuel needs. A Twin Air filter($21) was used for additional flow into the engine and Big Gun's Evo exhaust system($449) expelled the hot gases. A DynaTech ignition($260) was also used to get the desired timing curve needed to produce additional ponies.
Chassis
Although from the beginning we have said that the Brute Force couldn't handle the power it has, FST upgraded the chassis and proved us wrong. They had to. Using the cross country racing circuit as a test bed, they had to build a chassis that was easy to control and took full advantage of FST's power upgrades. To cure the Brute's handling woes, FST installed a set of Elka fully adjustable shocks ($1895). The shocks lowered the ride height of the quad about two inches while not giving up any travel. Ground clearance was reduced to about nine inches(stock is 10.6). For even more control, FST modified a Dura Blue Sway bar($440) and attached it to the rear end of the Brute's frame. For tires, FST chose to mount a set of Maxxis All Trax($370 a set) on Douglas wheels with OMF beadlocks and Outlaw reinforcing rings on the inside. The wheel package was a bit pricey at $285 per wheel. The All Trax tires measured the same as stock but their contact patch is much wider than the stock Dunlop's. To steer the rebuilt Brute, FST installed a set of Flex handlebars($300) equipped with Powermadd handguards($55). Weight was saved with the removal of the stock racks. This was a good trade-off for the added weight of Aluminum products full skid package($559) that replaced the worthless stock plastic guards. The FST racer was finished off with a 2500 series Ramsey winch($350).
Riding Giants
To get a feel of how the 840cc FST Brute performed, we took it for a spin at a recent GNCC event. From the push of the starter button, this thing rumbles power. It fires up quickly thanks to the dialed in ignition and purrs nicely with very little vibration. This can be partially attributed to the equal length head pipes from Big Gun. If you are looking to order an exhaust system for any V-twin engine, make sure the head pipes have the same measurement back to the muffler(or mufflers). Some do not and should be avoided. Out on the track, this monster was not hard to ride. You actually feel lower and the chassis feels much more stable than stock. Getting on the gas, this machine rockets in and out of the trees without hesitation. The clutch kicks in early and powers the quad forward even without a pinned throttle.
On The Gas
In the open fields at full throttle, this Brute will get up to a top speed of 70 mph in seconds even with a stock clutch. In two or four wheel drive, the Maxxis tires hook up and almost rip the bars from your hands. Gone is the tendency to push in the corners or wheelie at full throttle. In the tight woods, the suspension works even better thanks to the added swaybar. It allows you to get on the throttle early while transferring weight to the inside of the wheel. We never had a problem with the reduced ground clearance, as the full skid plate allowed the nearly 700 pound machine to glide over downed logs and rocks with complete protection. Although we got the machine muddy, we didn't have to use the Ramsey winch during this test.
What Did We Think?
With tons of power on tap, the 840cc Brute never hesitated when we put a load on the motor climbing hills, in the mud or sand. With about a half throttle push, it would power through anything. This engine kit would work great for a lifted mud machine or shined-up-duner. It screams horsepower, is easy to control and the perfect hop-up for any V-Twin Kawasaki you might own. The parts are easy to bolt on in your garage or by a neighborhood dealer.
The cc war is on. From the manufacturers to hop-up shops to race teams, everyone is trying to build the biggest ATV motors around. The latest entry into this war is from none other than Four Stroke Tech (FST). FST is one of many engine companies who use their race teams to test and develop products they sell to the public. Their latest creation raises the bar to the 840cc mark. The machine we tested, a Kawasaki Brute Force 750, is one of the fastest in stock trim, so adding almost 100cc made it a monster.
Why
Aside from racers, there are a growing number of customers, primarily from the southern U.S., who need all the power they can get. These guys are the mud runners. Equipped with six-inch lifts and 30-inch tires, this breed of ATVers lives for riding in the deep gumbo mud found in that region. The mud robs power. But unlike the power hungry sand-duners of the west, these guys don't mind the weight of a big utility machine. In fact, utility four wheelers are the vehicles of choice down there. Plus they can easily haul a cooler full of beverages needed for a day of riding. To develop the huge 840cc racer, FST started with a stock 2005 Brute Force 750. The hop-up kits FST sells will fit on any size Prairie, V-Force or Brute Force model. The unique feature of this machine is its camouflage color. Most race quads we feature have bright colors, but this machine really does stand out. At least at the races, that is. Another unique item found on the racer is a small Ramsey winch. Even though the winch may add extra weight, in mud bog events and in some cases for cross-country racing, they are a necessity.
840cc's
To expand the Brute Force's engine to the 840cc mark, FST uses one of their easy to install big bore kits. The kit includes Nik-A-Sil cylinders($460) and two 90mm(stock is 85mm), 11:1 Wiseco pistons(stock is 8:1) ($390). To match the bigger cylinders, FST does a port job on the head ($600), welds the rocker arms($260), installs new valve springs($190), new longer duration cams($400) and Cometic gaskets($60). With the increased engine size , FST had to find an airflow combo that optimized the compression and was adequate for fuel needs. A Twin Air filter($21) was used for additional flow into the engine and Big Gun's Evo exhaust system($449) expelled the hot gases. A DynaTech ignition($260) was also used to get the desired timing curve needed to produce additional ponies.
Chassis
Although from the beginning we have said that the Brute Force couldn't handle the power it has, FST upgraded the chassis and proved us wrong. They had to. Using the cross country racing circuit as a test bed, they had to build a chassis that was easy to control and took full advantage of FST's power upgrades. To cure the Brute's handling woes, FST installed a set of Elka fully adjustable shocks ($1895). The shocks lowered the ride height of the quad about two inches while not giving up any travel. Ground clearance was reduced to about nine inches(stock is 10.6). For even more control, FST modified a Dura Blue Sway bar($440) and attached it to the rear end of the Brute's frame. For tires, FST chose to mount a set of Maxxis All Trax($370 a set) on Douglas wheels with OMF beadlocks and Outlaw reinforcing rings on the inside. The wheel package was a bit pricey at $285 per wheel. The All Trax tires measured the same as stock but their contact patch is much wider than the stock Dunlop's. To steer the rebuilt Brute, FST installed a set of Flex handlebars($300) equipped with Powermadd handguards($55). Weight was saved with the removal of the stock racks. This was a good trade-off for the added weight of Aluminum products full skid package($559) that replaced the worthless stock plastic guards. The FST racer was finished off with a 2500 series Ramsey winch($350).
Riding Giants
To get a feel of how the 840cc FST Brute performed, we took it for a spin at a recent GNCC event. From the push of the starter button, this thing rumbles power. It fires up quickly thanks to the dialed in ignition and purrs nicely with very little vibration. This can be partially attributed to the equal length head pipes from Big Gun. If you are looking to order an exhaust system for any V-twin engine, make sure the head pipes have the same measurement back to the muffler(or mufflers). Some do not and should be avoided. Out on the track, this monster was not hard to ride. You actually feel lower and the chassis feels much more stable than stock. Getting on the gas, this machine rockets in and out of the trees without hesitation. The clutch kicks in early and powers the quad forward even without a pinned throttle.
On The Gas
In the open fields at full throttle, this Brute will get up to a top speed of 70 mph in seconds even with a stock clutch. In two or four wheel drive, the Maxxis tires hook up and almost rip the bars from your hands. Gone is the tendency to push in the corners or wheelie at full throttle. In the tight woods, the suspension works even better thanks to the added swaybar. It allows you to get on the throttle early while transferring weight to the inside of the wheel. We never had a problem with the reduced ground clearance, as the full skid plate allowed the nearly 700 pound machine to glide over downed logs and rocks with complete protection. Although we got the machine muddy, we didn't have to use the Ramsey winch during this test.
What Did We Think?
With tons of power on tap, the 840cc Brute never hesitated when we put a load on the motor climbing hills, in the mud or sand. With about a half throttle push, it would power through anything. This engine kit would work great for a lifted mud machine or shined-up-duner. It screams horsepower, is easy to control and the perfect hop-up for any V-Twin Kawasaki you might own. The parts are easy to bolt on in your garage or by a neighborhood dealer.
#2
01-11-2006, 05:48 PM
#3
01-11-2006, 10:39 PM
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01-12-2006, 01:17 PM
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01-12-2006, 10:14 PM
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#8
01-13-2006, 10:44 AM
FST 840cc Brute Force
I actually rode that atv for about 500 miles and it handled great. Its hard to control in tight situations where finess is needed but other than that the handleing was fine. It had Elka 3-way adjustable shocks all around and Answer Pro-Taper handlebars with Rox risers for a much better feel. I would power slide like a SRA but soaked up ruts like the IRS it is. I wish my P650 rode and handled like the BF840 does.
People sell things for different reasons. Doug and Mickey had problems and Doug was used to his 2wd V-Force so Doug traded even to Jim Stakk for a bran new YFZ450. Jim Stakk had trouble riding it in the GNCC and said it didnt handle the way he wanted or something to that effect. He hit a tree among other things and finally decided to sell it. Thats where I came in at. I sold it for various reasons, there was nothing wrong with it. It was in a lot better condition when I sold it than when I bought it. I keep in touch with the current owner about once a month and he says he is loving the BF840.
There is a little history lesson for some of you who may be interested in the ATV in the magazine. The engine built by Mickey D was/is rock solid.
People sell things for different reasons. Doug and Mickey had problems and Doug was used to his 2wd V-Force so Doug traded even to Jim Stakk for a bran new YFZ450. Jim Stakk had trouble riding it in the GNCC and said it didnt handle the way he wanted or something to that effect. He hit a tree among other things and finally decided to sell it. Thats where I came in at. I sold it for various reasons, there was nothing wrong with it. It was in a lot better condition when I sold it than when I bought it. I keep in touch with the current owner about once a month and he says he is loving the BF840.
There is a little history lesson for some of you who may be interested in the ATV in the magazine. The engine built by Mickey D was/is rock solid.
#9
01-13-2006, 12:52 PM
#10
01-13-2006, 04:42 PM
