2002.5 ZR 900

More of the good stuff, less of the tough stuff
RELATED TOPICS: ARCTIC CAT | SNOWMOBILES | ENGINES
When Arctic Cat first rolled out its 800 twin, we made note that the engine package was brand new from the crank up. It made sense to us that a bigger twin was coming since the engine block was significantly bigger than the 500/600 platform. At the 2003 model line intro, we found our observations were on target. Sitting in the conference room at Arctic Cat HQ was a brand new 862cc Suzuki twin.

"This is the heart of our new muscle sled," explained Product Manager Joel Hallstrom. "I know a lot of you thought, when you first saw the 800 a couple years back, that it looked like bigger pistons would fit pretty easy in the cylinders. They do."

The 900 twin will come with TM40 flat slide carbs this season. When we asked about EFI, we were told that the 800 was going to be the fuel injected option in the class for this year. Read into that what you will.

Engine leader Greg Spaulding gave us a quick tour of the new mill. "This engine was my favorite last year in testing," he said. "It makes horsepower… safe horsepower and a lot of torque. All at a low rpm."

The bottom half of the engine is the same as the 800, including the reeds, crank and case. But the upper half is completely new. "This isn't just a punched out 800 engine," he explained. "It has a whole new cylinder on it. The exhaust port shape and timing area is all changed. There's a new ignition timing map on the engine. The cylinder head is different, too." With the new engine comes a new exhaust system, right down to the y-pipe.

The design team anticipated our next question about the motor by designing a decompression valve in the cylinders right above an auxiliary exhaust port. "This will only be on the ZR sleds," Spaulding explained. "We found that there was a performance lag in the higher altitudes when we had the decompression in place. We'll be plugging the hole for all of the Mountain Cats. With the thinner air up there, we feel that it pulls over just fine.

"It's such a nice motor," he repeated. "It's fun to drive. It just pulls on your arms right from takeoff."

The initial riding on our test unit delivered between 10 and 11 mpg, with the throttle pinned for most of that time. Spaulding estimated that a guy actually riding at trail speeds (40-60 mph) for a day could expect to find somewhere in the range of the upper middle teens for mileage. But with power delivery like the ZR 900 offers, there will be a lot of pinned throttles.

Our dyno session found the ZR 900 actually produces an extra horsepower over Cat's claim of 150. Aside form the phenomenal amount of horsepower it cranks out, we were impressed with the broadness of the torque curve. It drops off a little just before the APV activates, but it holds above 100 foot pounds from 6000 rpm up to 7500.

With that kind of curve, the 900s should be easy to clutch and tune.
Cat's 900 twin will be a serious foe for any stock sled on the lake or on the hill. It may even send a few mod guys back to the trailer in shame.

2002 1/2 ZR 900
Air Density: 101.0
Fuel: 94 Octane Pump Gas
RPMCBTCBHPBSFCFUEL
500086.382.0.4636.9
510088.986.1.4740.0
520091.089.9.5246.2
530094.295.0.6157.5
540096.799.3.6462.9
550093.397.7.7067.4
560095.5101.8.7070.9
570095.9104.0.7072.4
580098.3108.7.6873.2
590099.5111.6.6673.5
6000100.7114.7.6775.8
6100103.0119.6.6779.2
6200104.4123.3.6882.6
6300105.0125.8.6884.6
6400105.4128.6.6886.4
6500104.9130.0.6887.3
6600104.5131.4.7090.5
6700104.2133.0.6991.5
6800104.2135.1.7093.3
6900103.4135.7.7093.8
7000102.6136.3.7094.7
7100108.3146.6.6594.4
7200110.1151.1.6394.3
7300108.3150.5.6697.8
7400106.0149.1.6999.5
7500103.1145.9.70101.1
760099.3143.2.71100.9


* RPM: Engine crankshaft speed • * CBT: Corrected Brake Torque • * CBHP: Corrected Brake Horsepower
* BSFC: Brake Specific Fuel Consumption • * FUEL: Actual fuel flow pounds per hour

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