Had two of the same year mopeds swaped engines to make one nice moped, fairly simple. Now the finished product is a 70cc kit with bigger carb and biturbo exhaust. Just had the clutch done and ran completely fine before I switched it, almost hitting 50. Then after the swap the first test run was great rode it about two miles and ran perfect almost hitting 50 still and the low end was amazing. Then it Sat for a few days until I could pick it up, I get home and ride it and now as I'm Hittin between 30 and 35 it just falls on its face (bogs down) and slowly keeps goin, doesn't cut off or anything, and the low end is now horrible. What could be the problem? The only thing I didn't swap was the cdi and they both seemed to appear like the same cdi, and if there was a restriction on the cdi at certain rpms why would it run fine the first trial run? Idk but I need some help figuring this problem out anyone have a clue?