all engines do not tune the same
when breaking in an engine , do not tune too lean on the lsn . once it is past break in (2 gallons or so) then set your hsn to be the control valve for the engines fuel intake , you want it to hit the powerband but not over rev
too rich on the lsn and too lean on top will drastically reduce the life span of the engine . most run on when coming off throttle is usually too rich on lsn and too big of a gap to compensate on the slide barrel (idle). if it runs on and makes a tingy sound that is too lean!!!
fix it
proper race tune : lsn as lean as possible(without lean bog) , idle as low as possible , use hsn to set top end before final adj. on lsn . 6 foot trail of smoke at least , nice crisp snap off of the bottom end (clutch depending) . remember to clutch your engine appropriately
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hope this helps ,
monty