if you have already tightened up the idle screw, and there is no difference,
that means its probably the air screw. Check with the manual and turn it to
the correct position. If the 70cc engine is made by the same manufacter, and
also has peddles, it is likley it will fit, but you have to remember one
different part on the engine will make it fit incorrectly. Also, the new
engine should not have the same problem unless the problem is with your gas
tank, or throttle cable.
Newsletters, Tips and Discussions on Your Favorite Topics