Yukon Trail Dirt Hawk 20 Owners Manual - Manual (Page 27)

DO NOT RETURN STORE. For questions regarding assembly and use, call Customer Service: 877-441-6999.
6. Depress the brake lever about 10 times as far as the grip to check that
everything is operating correctly and that the shoe clearance is corrected
before riding the bike.
Chain Adjustment
Inspection
The chain must be kept clean, rust free and frequently lubricated in order to
extend its life as long as possible. It require replacement if it stretches,
breaks,or causes inefficient gear shifting. Make sure that there are no stiff
links, they must all move freely.
Lubrication
The chain should be lubricated with light oil at least every month, or more
often in wet, muddy, or dusty conditions. Take care to wipe off excess oil,
and not to get oil on the tires or rim braking surfaces