Due to wear and use the clearance between the valves increases, so that these valves have to be set from time to time. The scooter can make a ticking, hissing or popping sound when there is too much play.
In addition, the performance of the scooter deteriorates what you may experience as a loss of power or a more difficult starting of the scooter. The valves of your scooter may have been burnt or the play of the tumbler may have expired.
The valves are pushed open by the tumblers at the moment that gases have to go in or out. To build the right compression it is crucial that the combustion chamber is completely airtight. When there is play between the valve and the tumbler, this means that the tumbler is still in contact with the valve and the valves do not close completely!
A cam of the underlying camshaft presses on the tappet via a cam follower and actuates the valve via a set screw on the rocker arm. The space between the tumbler and the valve stem is the valve clearance
The cam of an overhead camshaft presses against a rocker arm, which in turn presses the valve stem via a set screw. The valve clearance can be adjusted by turning the adjusting screw.
Between the cam of an overhead camshaft and the cam follower is a metal shim with such a thickness that there is just enough clearance between the ridge and the plate. The shims are available in different thicknesses. If the valve clearance is too large or too small, this plate can be replaced by a thicker or thinner plate to compensate for the deviation in the valve clearance.
Answer: Due to hot conditions, the valves turn off and the valve stem becomes longer. To compensate for this extension, there must be minimal space between the operation of the valve and the valve stem!
Answer: Ideally, the valves must be set every 3,000 km, however, the standard is around 8,000 and at 10,000 you will notice significant difference in consumption, waiting too long results in engine block damage.