Yamaha YFM400AS, Owner'S Manual

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6-7
EBU02101
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.
During the first 20 hours, the various parts in
the engine wear and polish themselves to the
correct 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 acceleration sequence
should be followed with a substantial rest pe-
riod 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 period, consult a Yamaha dealer.
0–10 hours:
Avoid continuous operation above half throt-
tle. Allow a cooling off period of five to ten min-
utes after every hour of operation. Vary the
speed of the machine from time to time. Do
not operate it at one set throttle position.
U5VH11.book Page 7 Friday, March 28, 2003 2:47 PM