KYMCO Downtown 350i Repair Manual page 210

4.Engine
Measure the inside diameter of the valve guides. Replace the guides if the
measurement is out of specification. Calculate the valve stem-to-guide clearance.
Replace the guide and valve if the clearance is out of specification.
Valve guide I.D.
Valve stem-to-guide clearance
Item
Downtown 350i
Standard (mm)
IN 5.00 - 5.012
EX 5.00 - 5.012
IN 0.010 - 0.037
EX 0.030 - 0.057
4-36