So I bought this '05 Rhino 660 mid July. I took a short spin in it before buying it and it ran OK, so I did the deal. I took it home and proceeded to check fluid levels, lubrication, etc, before I rode it. Worst problem was it took about 3 seconds for the starter to turn the engine through the compression cycle, then it started right up. I read on here about the decompressor/camshaft timing and didn't really want to get into that. I checked all the electrical connections, installed a 410 CCA battery, a #4 battery cable, and an automotive type relay. Starter still labored. Also the engine would smother and falter above 1/2 throttle unless the air filter was removed. I had noticed a new cylinder on the engine, something the previous owner didn't mention. I decided to bite the bullet and check the cam timing. I put the engine to TDC and pulled the cam cover. Sure enough, the cam was about 2- 3 teeth advanced. The decompression mechanism worked good. With the cam advanced, the engine decompresses earlier in the compression stroke, leaving more stroke to develop compression. That is my theory, anyway. I reset the timing, turned it through a couple of revs and put it back together. It cranked without any hesitation and I drove it about 300 ft out of the shop before it quit running. I pulled it back to the shop, pulled the covers and saw oil had sprayed out of the tensioner hole. I had failed to put the tensioner back in. I put the tensioner in and tried to start it and it blew the carb off the intake manifold. I pulled the head and took it to a cycle shop the get the bent valve replaced. It is back together and it starts before I can take my hand off the key. It no longer stumbles at 1/2 throttle and runs better than it has since I got it. I'm telling my story as a testimony to the importance of the cam timing to starting and running. If you have weird symptoms and reason to think the timing might be out, check it and save yourself some misery.