2000 ZR 600 Carb

This Cat's one hot runner!
The case reed Suzuki 600 twin engine has been on the market for two seasons. It has been available in both carburetted and fuel injected versions, using the same engine package. However, Arctic Cat's engineering department learned through the course of testing that the two different fuel delivery systems each responded better to slightly different engine internal configurations.

The 2000 ZR 600 Carb sled features a slightly beefed up engine case and a heavier crank. It also sports a new, higher volume exhaust pipe to help it breathe more easily.

This setup was first introduced on the very limited edition Millennium ZR 600 last spring. It will be the norm on all 600 carb sleds for this season, as Cat says it is five percent more potent than last year's setup. Our dyno sessions concur with Cat's statements. The modifications to the engine have brought the carb version on par with the EFI model.

"This was an interesting engine to test," noted dynoman Rich Daly. "Because it has such big airflow, we decided to pull some slower tests. It held the power very well, which means it should be very forgiving on long lake blasts. Cat probably could have tuned the engine a horse or two higher with a tighter stinger, but it wouldn't have been as consumer-friendly.

"We started making longer, slower acceleration runs of about two seconds per 100 rpm," said Daly. "That's how we found the full power of the sled. It just needs to be hot. When you're making long, hot runs, you need to be jetted a little richer to avoid burndown.

"The new, large pipe outlet on the sled doesn't work to its potential unless it's hot. We tested this by pulling two runs back-to-back. Usually a motor will lose a little when it's that hot. But the second test put an identical line over the first pass. The ZR 600 engine didn't drop off. Not a bit."

By Daly's testing notes, the twin is fairly responsive to jetting, but offers a one or two main jet size forgiveness zone. "We went one size leaner than our best test and got the same power, but the band was much narrower. One size richer and we were only short by a fraction of a horsepower. This should be an easy sled for most consumers to jet safely."

The power band on the ZR 600 is also quite generous, we hit power figures above 103 hp from 8100 through 8500 rpm, with the torque coming in just prior- from 7800 through 8300. Consumers will have an easy tuning target to shoot for with this sled.

Those who trail ride the ZR 600 Carb will be able to maintain the heat under the hood with little problem. However, if lake racing is the day's activity, Cat fans should plan to spend a few minutes getting the powerplant up to heat before trying to take the competition to the cleaners.

"Our best run was 105.4 horsepower at 8300 rpm," said Daly. "In speaking with Cat's dyno room engineer, that is more or less what they found in their testing program. I think we were spot-on with this one."
One last note to the hot rod consumer who is going to be pulling the sled apart and putting it back together: you have to be sure that all of the electronic sensors and connections are returned exactly the way they came in the crate. Daly noted that his assistant inadvertently forgot to reconnect an ignition timing sensor on a pass and it dropped six horsepower instantly. If you forget something, your sled will let you know as soon as you're running!

We owe a very special thanks to George Cook, from Cook's Recreation (315/695-5121) for the last minute use of a sales floor sled. If you're in the Otisco, NY area, stop by, say hi and take a look through the store.
2000 ZR 600 Carb
Air Density: 100.7
Fuel: 93 Octane Pump Gas

680051.867.1 .69346.8188.4
8000 66.9102.0.57458.9188.4

RPM: Engine crankshaft speed.
CBT: Corrected Brake Torque.
CBHP: Corrected Brake Horsepower.
BSFC: Brake Specific Fuel Consumption.
FUEL: Actual fuel flow pounds per hour.
AIR: Actual air flow in pounds per hour.
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