I've spent a good amount of time searching for an answer in the search feature with no luck, so I apologize if I am missing somethign.... I have a 2006 WR450 that I just checked the valves on and shimmed. It appeared that the shims had never been replaced based on the sizes that were installed. One intake and one exhaust valve were just outside of spec (.001-inch too tight), but I went ahead and reshimmed every valve back to nominal. I have no idea how many miles are on this beast, but I'm sure it is quite a few... With that out of the way, I've never had trouble kicking the bike over. Now that I put it back together, it is very difficult to kick. It starts very easy using the electric starter, and it turns over easily with the spark plug out when turning it over using a socket on the crankshaft. Before putting the valve cover back on, I turned the engine over quite a few times with the socket on the crankshaft to verify everything moved easily and that there wasn't any valve to piston contact. I also checked the decompression cam while it was apart, and it moved nice and smoothly. Then, when I put it back together, I just fired it up using the electric starter and it ran great. I did a 50 mile ride with it yesterday, and it ran great all day. However, I tried kicking it a few times, and it was really hard to turn the engine over with the kick starter. I don't remember it ever being this hard, as before, I could pretty much just easily push the lever down unless I got it stock at TDC. Now, every kick is a bear to do. Before, after the bike was warmed, an easy, full stroke kick or two would start it every time. It seemed like it might be getting a little easier to kick, but I didn't want to damage anything, so I stuck to the electric starter for the whole day. Any thoughts on where I should look for improper assembly, damage, etc. that would cause the bike to be really hard to kick?