2001 skidoo mx z x 800

We had our hands on an early-release Ski-Doo MX Z X 800 earlier this summer, and of course we couldn't resist putting it on the bench of truth.

This latest addition to the Rotax Series 3 family has its roots in the 700 class, although you wouldn't guess it by its measurements. The 697.7cc engine measures 78mm across with a 73mm stroke. Rotax designers bored out the cylinders to 82mm for the 799cc engine. But they didn't stop there. The crank and rods were modified to accommodate a longer 75.7mm stroke as well.

There are a few unique durability and functionality features on this engine. For instance, the case is presealed with oil for protection against contaminants, as well as crankshaft bearing lubrication assurance. And instead of injecting two-stroke oil into the fuel air mixture through the carburetor, as other sled engines do, Rotax has opted to place the injector directly on the case. This is the way most major marine engines operate.

The carburetors on the 800 twin will also be slightly modified from the Mikuni flat slides found on competitive sleds. Bombardier engineers worked with the vendor to develop a design which eliminates the openings for pilot jets and also the venturi found at the needle. These changes were made to improve the unit's responsiveness and also to combat icing problems Ski-Doo developers discovered while testing.

The whole package proved to be a potent one and a consistent one. By our test session, we found the engine produces a nice, wide torque band above 90 foot pounds from 7400 through 7800 rpm, with the peak 91.5 foot pounds coming in at 7600. The 134.1 horsepower peak hits at 7800 rpm.

"This is a very consistent engine for a big twin," said our Dynoman, Rich Daly from Dynoport. "We took it down a couple of jet sizes for the conditions and it made good power. Once we got to a point where we made the best runs, we took three pulls in a row. From beginning to end we maybe lost a horse. That tells us this sled will do well for guys who make multiple runs up and down the lakes.

"We varied the water temperature for those runs, but left the pipe and silencer hot. It didn't matter a whole lot. With the cooler water in, the peak shifted down 100 rpm and only lost two tenths of a horsepower.

"The upshot of the whole test session," concluded Daly, "is that this engine will run the same, even if the conditions change a little during the day. You're not going to need to bring a jet box along to get good performance from the MX Z 800."

Special thanks to Tri-State Sports Center for providing our test sled. Tri-State Sports Center, RR 4 Rt. 6, Honesdale, PA 18431 • 517/253-6323.