I'm new to the forum, and new to 4 strokes in general. I have always been a 2 stroke fan, but I picked up an 04 450 with a few nice mods for $800. The bike did not run, and the seller said that he thought it had jumped time. He said that he was riding the bike, shut if off normally, and it would not start again, crank and crank and crank, nothing. I have spent all day researching and tearing the bike down. This is what I found: Line the crank up at TDC( I couldn't find a line, but I found a dot on the flywheel through the timing mark hole, and using a screwdriver verified that the piston was at TDC.) The Intake side cam was 1 tooth off and the exhaust cam was 2 teeth off. The timing marks I used I got from a picture on google that showed the cams had a divot at the 12 o'clock and 3 o'clock position and I lined those up flush with the head surface. The chain was tight, the cam gears have no sign of slippage, breakage etc. I reassembled the motor, checked the carb, and it was clean cranked until I was blue in the face, still no signs of life. Spark was fine, everything was there, Just wouldn't fire up. Roll started it down a hill, it would run, but it killed out like it hadn't been ran in years. The plug when pulled back out was black and wetttttttt. Which leads me to believe it is in the carb. As for the carb, The seller said it had the Accelerator pump mod, Done with an O-ring? I don't even know what an accelerator pump is, lol and it appears to have no hot start, and the choke will pull out, but will not stay pulled out. I know most of these bikes had a remote hot start on the handlebars, but this one doesn't have it. He said that he installed a JD Jet kit in the carb, and bumped the main up to a 175. What is the stock jetting or at least a baseline setting as far as air screw etc? I am lost at this point! I know a motor has to have air, fuel and spark, but a thumper is a whole new ball game for me, could a valve be warped? Could the valves need shimmed? It is in the carb? Any help to get me out of this jam would be greatly appreciated? I would like to know how the carb is supposed to go back together properly. Thanks in advance!