This is my first bike. Aluminum Onex 29ner from Walmart. This Balanced PK80 66cc from Ozark Cruisers:http://ozarkcruisers.com/product/two-stroke-pk80-engine-kit/ Here are issues: 1: from beginning I have worried about clutch. It makes sort of a "bark" when first engaging. I know that is normal. But as I continue to pick up speed it continues to bark a little as if it may be slipping? Not sure that it is and this may be normal. BUT yesterday I rode and reached 35mph and the motor reaching highest rpm to date. When I got back the clutch would not disengage. I carried the bike into the work room and left it. After it cooled off the clutch was stuck in the DISENGAGED position. How did it go from not disengaging to disengaged just by cooling off? I took cover off sprocket and taped the bolt holding sprocket and clutch popped loose and seems to be working now. Is there some adjustment I need to make? 2: the motor has been slow to get up to full rpm. It would run very well at medium speed until I got to full throttle and would then "bog down" for lack of better description. If I eased off on throttle it would reach higher rpm and run better. This issue has reduced over time. Yesterday it seemed to almost be gone completely and motor reached significantly higher rpm. BUT at the highest rpm the vibration is really bad. Motor is firmly attached but vibration in seat is actually painful, literally. Is this possibly caused by rough carb issues? PS this is in an aluminum 29ner I would have thought top speed wood be closer to 40 on such large wheels, no? I weigh 170. Any advice is appreciated!