Hi, I recently bought a 83 Johnson 70hp. Rebuilt carbs, changed fuel lines, changed plugs, compression is 132/140/130. My engine boggs down as soon as I reach about 30% throttle,,,if I pull back to idle and then hit the throttle all the way it comes to life perfectly and runs great. I have tried pumping the fuel bulb when it starts to bogg and the bulb is hard and it doesn't effect the engine. This problem is worst upon first start before the engine warms up. If I give it about 30% on the shifter and then open the carbs WOT by hand it responds, also it responds by blirbing the carb linkage only. In reverse it won't take hardly any throttle at all(but if I push the carb linkage it responds and revs all I need all the way to WOT). Does the problem exist because the timing isn't at the right spot? How does the timing advance when engine is cold? I guess it is the linkage sych? Does anyone have the manual pages for sych? Don't really want to spend the $ for a manual cause I'm probably not going to keep the boat. Thanks in advance for any replies have been losing sleep trying to fix this!