Maintenance - Desert Aircraft DA120 Owner's Manual

• Make sure prop is flipped over with authority. The ignition won't fire at low speed.
• If a lot of fuel drips from carb, the motor might be flooded. If so, remove and dry, or replace, the
spark plugs. Try starting again without using the choke.
Other issues
• Fuel drips continually from carb: Check that the pin on the center of the diaphragm is inserted in the
metering lever "fork". Make sure there is no debris in the needle seat. Remove needles and blow
air into the holes.
• RPM won't go over 3,500 to 4,000: Check that the polarity of the connection between sensor and
ignition is correct (not plugged in backwards).
• Broken prop bolts: In order for bolts to shear, some type of side loading (shear) movement is
usually required. If the bolts are tightened correctly, nothing moves and prop bolts will rarely break.
It's a good idea to replace prop bolts routinely. Check prop bolts before each flight!
• Excessive vibration: Check that low rpm needle setting is not too rich. Check prop and spinner
balance. Make sure ignition timing is correct.
• Pink or purple colored cylinders: These colors indicate engine temperature has been too high.
Check that needle settings are not too lean, air flow for cooling is sufficient, oil/gas mixture is
correct.
• Engine starts backwards: Make sure prop is flipped forcefully through the compression stroke.
Without enough force, the prop may "bounce" off compression and run backwards.
IF ANY PROBLEM PERSISTS, PLEASE CONTACT
We designed and manufactured your engine and have built, serviced, and analyzed thousands more.
We cover your engine's warranty, not someone at the field or a stranger on the Internet. Please give us
the opportunity to help first!

Maintenance

• Being a high performance 2 stroke engine, certain parts can wear quickly. Under normal operation,
pistons, piston rings, needle bearings, spark plugs, etc. may need occasional non-warranty
replacement to insure peak performance.
• Screws can come loose! After a few flights check that all screws are secure. Periodically check that
all screws are tightened to the correct torque rating. It's recommended to replace, rather than re-use
the red aluminum screws.
Spark plug:
Steel prop bolts:
Aluminum crankcase bolts:
Steel cylinder base bolts:
Steel carb mount bolts:
Aluminum carb mount bolts:
Steel motor mount bolts:
*Caution: Care must be taken to not over tighten the carb mounting bolts. Over tightening can
distort and damage the injected molded reed valve parts and rubber gaskets.
DESERT AIRCRAFT FIRST!
Size
CM-6, 10mm
M5x 50mm
M5x16mm
M5x16mm
M5x75mm
M5x75mm
M6x16mm
(Cont'd)
6
Torque specifications
90 in. lbs.
65 in. lbs. / wood props, 80 in. lbs. /carbon props.
70 in. lbs.
95 in. lbs.
50 in. lbs.*
25 in. lbs.*
120 in. lbs.