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The early 1990s marked a revolution in rear suspension design. Initiated by the Karpik brothers in northeastern Minnesota and led by former cross-country racing champion Gerard Karpik, an effort was spearheaded to bring long travel to snowmobile suspensions.
The Karpiks' created a stir when they released their first M-10 rear suspensions to the public. Successfully race-tested in Scandinavian snocross events, the M-10 immediately found a following with performance riders in the U.S.
The beauty of the M-10 design was its flexibility - both in overall suspension travel and in its ability to be adapted to a variety of brands and models.
Naturally, as maker of the No. 1 selling brand and the self-professed technology leader, Polaris had to respond. Frankly, the company's first effort was stellar. Designated XTRA-14 and fitted to a pilot build of Indy Xtra Lite Triples, the Indy XLT XTRA was a joy.
Pilot vs. productionFor you collectors, finding one of these pilot-build XTRA-14 sleds will be a challenge as Polaris revamped its long-travel rear suspension between the pilot runs and the next season's production.
The original release was said to be the "next step in snowmobile ride and handling." It featured 13.6 inches of rear travel combined with 10 inches of front travel from the revised front suspension.
The XTRA-14 suspension performed way better than expected. It gobbled up stutter bumps and compressed smoothly when absorbing those wallowing suspension-sucking jolts.
This first XTRA suspension came with rebuildable Vector-designated gas shocks, front and rear.
In actuality the XLT XTRA was illegal on some trails as its ski stance, which set at 43.5 inches when uncompressed, actually measured 49 inches center-to-center under full compression. That put it outside the 48-inch ski stance permitted on some grant-in-aid trail systems.
While the ride was phenomenal, there were some disadvantages. The ride height brought the center of gravity up enough to give the sled a totally different riding experience on tight trails. Sitting higher than a normal Indy made the XLT XTRA lean more. We discovered in testing that the XTRA suspension reduced top speed vs. a standard Polaris suspension. The XTRA resulted in some "ballooning" of the track that could reduce top speed by as much as 5 mph.
Overall this first XLT XTRA was, perhaps, the best example of a modern long-travel suspended sports sled. Finding one today may be tough.
While the next iteration of XLT XTRA models featured the same 597cc lightweight triple, the rear suspension underwent a change to make the sled better in tight turns and faster at top end.
In the second iteration Polaris discarded the Vector shocks in favor of Fox gas shocks. The ride height got lower for better handling as the rear suspension travel went to 13.1 inches from the original 13.6. In addition the "upgraded" XTRA suspension featured dual shocks on the rear suspension arms vs. the single, longer stroke shock on the rear torque arm!
In a span of about 30 days we tested two totally different XLT XTRA sleds in 1994. The first XLT XTRA actually had the better ride, but because Polaris felt the higher ride height and loss of top speed were negatives, it reinvented the rear suspension to bring the ride characteristics closer to a standard Indy XCR sports sled. Despite the specifications claiming that only about .5 inches had been removed, in effect the revised XTRA suspension had nearly 2 inches of travel taken out. You could tell the difference. The original was our first choice for comfort.
As for the Karpiks' M-10, a modern version can be found in today's Polaris models!