Yamaha 4SH-28199-67, Owner'S Manual

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Engine break-in
There is never a more important period in the
life of your machine than the period between
zero and 20 hours.
For this reason, we ask that you carefully read
the following material. Because the engine is
brand new, you must not put an excessive load
on it for the first several hours of running. Dur-
ing the first 20 hours, the various parts in the
engine wear and polish themselves to the cor-
rect operating clearances.
During this period, prolonged full throttle oper-
ation or any condition which might result in ex-
cessive engine heating must be avoided.
However, momentary (2 ~ 3 seconds maxi-
mum) full throttle operation under load does
not harm the engine. Each full throttle acceler-
ation sequence should be followed with a sub-
stantial rest period for the engine by cruising at
lower r/min so the engine can rid itself of the
temporary build up of heat.
If any abnormality is noticed during this peri-
od, consult a Yamaha dealer.