AmSnow.com is now SnoWest.com
We received a bonus sled for our long term testing purposes last February, a limited build 2001 ZR 600 with Arctic Cat's variable exhaust valve system. Once we took possession of this sled, the remainder of the Arctic Cats seemed noisy and outdated.
Cat officials heralded the new Arctic Power Valve (APV) mill as a quieter, stronger and more fuel-efficient engine. To our best observations, they were three for three.
Greg Spaulding (Cat's engine guru) gave a short presentation on the new engine, when we were up in Thief River Falls for an introduction. One of the most important things, he noted, was that the new generation engines are much quieter than we would be used to. One of the benefits Cat achieves with the variable exhaust valves is a muffling of exhaust noise when the valves are closed.
The servo-controlled valve pops open at 6950 rpm and snaps closed again when the engine drops to 6850. "By using the servo to actuate the exhaust valves," commented Spaulding, "we can control exactly when the valves open and close. It's much more precise than systems that use air pressures.
Also, we have a self-cleaning and diagnostic feature when the sled is fired up. We also have a bleed line that runs out of the valve housing, which will evacuate any escaping air and residue away from the valve itself. This should keep the system from fouling up." However if there is some sort of failure, the system will go into a survival mode so you can get it back to the dealership without worry of additional mechanical difficulty.
Our test sled showed no sign of APV difficulties. We used Spectro Gold synthetic blend oil and the auto-clean function kept the engine's performance sharp throughout the two-week test period.
Like every other snowmobiler in the Minneapolis/St. Paul, Minnesota area, we found only marginal conditions for riding around home. Warm weather and low snowfalls meant a dearth of base on the trail system we used for putting miles on the sled. In spite of the abuse the sled received in the warm and dirty conditions, we did not experience a single failure. Not even a fouled plug!
Of course, the wear parts went on an accelerated wear schedule. In just the 389 miles we accrued on the ZR 600 APV, we did manage to run all of the carbide off the skis, and we took the hyfax down to a thin skin. But that's our fault, not the sled's.
Due to the exceptionally poor riding season we had in February, we did not get a chance to really tune the sled to its potential and run it on the radar. But we did get a very good feel for how it runs out of the box. On our rain-soaked speed testing day, we found 83 miles per hour was the top speed in roughly a quarter mile, in slush and heavy wet snow, without any tuning whatsoever. Though the number is low, it was exactly what the other sleds we tested that day ran- Polaris' 2001 EDGE 600 XC SP, Arctic Cat's 2000 ZR 700 and ZR 600 EFI.
We found an average fuel consumption of a little over 13 miles per gallon. Not quite up to Cat's claimed 16-18 mpg. We'll concede a little to running rich in poor conditions, but we'd be impressed if anyone could pull those kind of numbers consistently on the trail all season long.
The only things we found to pick on with this sled lie in the fit and finish department. We noted the speedometer cable coating melted away, as it was in contact with the hot exhaust pipe. It didn't hurt the gauge's performance, but it did expose the inner steel sheathing to corrosion.
Additionally, with only a few weeks of getting hauled in the back of a pickup, the ZR's pipe and canister all started showing signs of rust. Someday, somehow, it would be nice if a company could devise a cost-effective coating to put on its pipes to avoid the situation (WD40 doesn't count!).
Overall, we'd say that Cat's 2001 ZR 600 APV was a popular member of our test fleet. It ran well under the worst of conditions and came back for more the next day. We would recommend the sled to a friend