Any rebuilt machine will need time to settle down, even if parts
have been replaced in their original order. For this reason it is
highly advisable to treat the machine gently for the first few miles
to ensure oil has circulated throughout the lubrication system and
that any new parts fitted have begun to bed down.
Even greater care is necessary if the engine has been rebored or
if a new crankshaft has been fitted. In the case of a rebore, the
engine will have to be run-in again, as if the machine were new.
This means greater use of the gearbox and a restraining hand on the
throttle until at least 500 miles have been covered. There is no
point in keeping to any set speed limit; the main requirement is to
keep a light loading on the engine and to gradually work up
performance until the 500 mile mark is reached. Experience is the
best guide since it is easy to tell when an engine is running
If at any time a lubrication failure is suspected, stop the
engine immediately, and investigate the cause. If any engine is run
without oil, even for a short period, irreparable engine damage is
When the engine has cooled down completely after the initial
run, recheck the various settings, especially the valve clearances.
During the run most of the engine components will have settled into
their normal working locations. Check the various oil levels,
particularly that of the engine as it may have dropped slightly now
that the various passages and recesses have filled.