Operating Instructions - Stihl HT 70 Instruction Manual

Operating Instructions

During break-in period
A factory new machine should not be run
at high revs (full throttle off load) for the
first three tank fillings. This avoids
unnecessary high loads during the
break-in period. As all moving parts
have to bed in during the break-in
period, the frictional resistances in the
engine are greater during this period.
The engine develops its maximum
power after about 5 to 15 tank fillings.
Do not make the mixture leaner to
achieve an apparent increase in
power – this could damage the
engine – see chapter "Adjusting the
Carburetor".
During operation
Check chain tension frequently!
A new chain has to be tensioned more
often than one that has been in use for
some time.
HT 70, HT 75
Cold chain
Tension is correct when the chain fits
snugly against the underside of the bar
and can still be pulled along the bar by
hand.
Retension if necessary –
see chapter "Tensioning the Saw Chain".
Chain at operating temperature
The chain stretches and begins to sag.
The drive links on the underside of the
bar must not come out of the bar groove
– the chain may otherwise jump off the
bar.
Retension the chain –
see chapter "Tensioning the Saw Chain".
Always slacken off the chain again
after finishing work. The chain
contracts as it cools down. If it is not
slackened off, it may damage the
crankshaft and bearings.
After a long period of full-throttle
operation
Allow engine to run for a while at idle
speed so that the heat in the engine can
be dissipated by flow of cooling air. This
protects engine-mounted components
(ignition, carburetor) from thermal
overload.
After finishing work
: Slacken off the chain if you have
retensioned it at operating
temperature during cutting work.
The chain contracts as it cools down. If it
is not slackened off, it may damage the
crankshaft and bearings.
Wait for engine to cool down. Drain the
fuel tank. Store the machine in a dry
place. Check tightness of nuts and
screws (not adjusting screws) at regular
intervals and retighten as necessary.
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