The 549cc single overhead cam, 4-valve, counterbalanced XP mill is a full level above its predecessor. T
his new 550 is similarly specked to the 550 Yamaha mill although the XP incorporates EFI with a slightly larger 42mm throttle body feeding oxygen into this thumping monster.
There’s a slightly rougher idle than the Yamaha and the XP is less impressive with heavy loads or when trying to get the front end up and out of a big mud hole.
Mid-range is where the XP comes alive. Here the EFI single finds its legs – pulling away from the Yamaha easily and running to big digits quickly.
Even a chopped throttle during a mid-range pull takes little time to recover from as the all-new fixed center CVT backshifts the XP to cruising speeds lightning fast.
While the longevity and durability of this all-new mill is still unknown, Polaris has had a good track record with its ATV motors.