Hey guys I've been trying to get my StingrayXL with KingsMB "80"cc engine back on the road. Everything is tracking smooth and it started up after a year with no problems within 10 feet. It idles fine and has enough power to make its own way up some pretty steep hills without pedaling. The problem I'm having that I haven't been able to figure out is the engine has a hard time accelerating after about 15mph and vibrates like theres no tomorrow. The engine even gets louder in the mid rpm's with how much it vibrates. It does this under load and with no load at all. When I'm going down a hill it still has a difficult time accelerating but smooths out a little bit once it gets up to speed. Not by much though. I checked my plug and its a nice chocolate brown so I know I'm not running rich or lean. I'm running the recommended 30:1 fuel mix. I have a boost bottle installed but it doesn't seem to make a difference in poor performance if I block it off or not. Any ideas? The spark plug is new. Checked to see if the exhaust was clogged which it isn't. Cleaned the air filter and carb. It's definitely getting enough fuel. If I choke it and give it gas it dies so no intake leak. This engine has probably about 1000 miles on it so its definitely broken in. Any ideas fellas? I really want to get this thing running well so my paps can go on some MB rides with me. Thanks in advance.