the "tinging" sound is defiantly coming from the piston area and from what i can tell it is near the head,
the exhaust is a stock exhaust the cylinder and piston is a 60 cc polini the carb is stock except the jet i went from a 52 to a 60 whats strange about this is i originally had this setup on this bike and it ran fine for over a year and a half then it started doing this about a month ago. i moved the engine, carb, exaust and tires same sprocket setup to a garelli step through frame. and it ran wonderfully for a month, but i only did this while i rebuilt my toptank which i just got done with and re mounted everything on the toptank and it started doing this again.
what i have done so far to troubleshoot cleaned carb, checked gas flow from tank, checked spark, changed spark plug, gaped spark plug, checked timing, checked chain to make sure it was not to tight and putting to much tension on the engine, checked that gas cap was letting air into the tank, put on new petcock, replaced float with new one, changed ND oil, removed cylinder and piston completely to check for ring and wear problems, drained gas and put in fresh remixed gas with synthetic 2 cycle.
all i am left with now that it could possibly be is i mounted the exhaust one hole closer because the other one was missing the rubber or it is an electric issue with the wiring of the bike itself not the flywheel
one electric issue with this bike i have never been able to solve is the break light i have to hardware the contacts on the handlebars together so it wont shut off when i put on the breaks and yes i have replaced the bulbs :) i have re wired the bike exactly like my other 2 garellis and still the same problem
also i did a plug-chop when it was doing this just to see what it would be and everything looked good
i guess tonight i will try completely replacing the taillight housing with one from another garelli i know works and clean and reconnect all grounds. clean the points, and put a new head on.
but hey this is one part of what makes mopeds fun.