Uncategorized Half the power and problems shifting gears. Help? April 22, 2016 dstech i have a 2005 grizzly 660 and my bike just dropped in power. It only goes about 31 mph now and struggles sometimes through mud holes. It’s also barely shifting in and out of gears. One of my freinds said it may be the rear diff? Any ideas???? Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related