Yamaha RD250(C) Owner's Manual page 68

Engine break-in
There is never a more important period, in the
life of your motorcycle, than the period
b e t w e e n zero and 1,000 k m . For this
the first 1,000 k m the various parts in the
lowing material. B e c a u s e the engine is brand
new, you must not put an excessive load on it
for the first several hours of running. Düring
the first 1,000 k m the various parts in the
engine w e a r and polish t h e m s e l v e s to the
correct operating clearances. Düring this
period prolonged füll throttle Operation, or
any condition w h i c h might result in excessive
heat of cylinder, must be avoided. H o w e v e r ,
m o m e n t a r y füll throttle Operation, under load
(2 ~ 3 s e c o n d s m a x i m u m ) , does not harm
the engine.
- 6 2 -