Motor Installation
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The DA35 can be mounted with or without the included stand-off spacer mounts. The ends of the spacers
with “flats” are mounted to the motor mount tabs with steel M5x16 metric screws (supplied). The engine is
mounted to the firewall with M5x25 mounting bolts and washers (supplied) that pass through the firewall
and thread into the round end of the standoff mount.
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We recommend blue Loctite on all engine mounting screws. Check the mounting bolts regularly to insure
they are tight.
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Thrust adjustments must be made by angling the firewall. Do not use shims, washers, or spacers behind
the supplied stand-off mounts. Un-even shim heights will cause stress, and possible damage, to the
engine case. The rear face of each stand-off must be mounted on the same surface plane.
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Do not use soft mounts with the supplied standoffs. The excess engine movement and vibration will cause
problems with exhaust systems, carburetor components, and linkages, as well as damage to the engine.
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Make sure the aircraft’s firewall and/or motor box are strong and secure. If flex or movement is detected, in
the mounting area, re-enforce the structure.
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Cooling is critical to motor performance and longevity. Allow as much cooling air as possible in through the
front inlets of the cowl. Allow an outlet opening approximately 2 1/2 times larger than the intake at the
bottom rear of the cowl for the hot air to escape. Air must flow through the cylinder fins, not just inside the
cowl, to properly cool the motor. Don't let the air take the easy way out! Make it go through the fins.
Round cowls with large frontal openings need ducting or shrouds to direct the air through the cylinder fins.
Any air not directed to the engine is wasted.
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Keep components like the ignition system, fuel tank, fuel lines, receivers, etc, away from, or shielded from,
heat generated by canister and tuned pipe exhaust systems. Hot fuel tanks and fuel lines can cause
frustrating tuning issues, and overheated electronic components can have intermittent problems or total
failures.
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Make sure the carburetor has adequate clearance near the inlet to allow an unobstructed airflow into the
carburetor. If the carburetor is located in front of the firewall, be sure there is at least 3/8” (10mm) of
clearance from the carburetor inlet. If there is less than this, make a hole larger than the carburetor inlet
diameter in the firewall to insure the carburetor’s intake is un-restricted.
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The throttle arm is tapped for a 4-40 SAE ball link. The return spring tension on the DA35 carburetor is
fairly light and we recommend leaving it in place. The spring reduces butterfly plate and shaft wear as well
as insuring the throttle closes if the servo linkage fails.
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The choke arm has tapped holes for a 4-40 SAE ball link. It can be rotated 360 degrees to allow access
from the rear, side, or front of the engine. A servo can be used or it can be operated manually. For
maximum security, once the arm’s position has been determined, a small flat spot can be filed or ground on
the choke shaft where the arm’s set screw seats. We also recommend thread locking compound like
Loctite.
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To prohibit vibration damage to the choke assembly, do not remove the detent ball and spring on the choke
shaft.
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Since the carburetor needles must often be adjusted differently with the cowl on as compared to off, we
recommend small access holes be made in the cowl for adjusting the needle valves with a long, narrow,
screwdriver.
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A 12 oz. fuel tank will typically be good for approx 12 minutes of flying time or more, depending on throttle
settings. Use a larger tank if you require more flying time. The tank must be vented. The carb has a strong
pump, so the tank can be mounted almost anywhere. The fuel line and tank stopper must be gas
compatible. Do not use any silicone sealers on the fuel system. Gas can break it down and carry it into the
carb.
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The inner diameter of the fuel tubing should be the same or larger than the carburetor's fuel inlet fitting's
inner diameter. 1/8” I.D. is recommended. Make sure all fuel line connections are secure. For extra
security, small nylon zip ties work well to keep the fuel line on the metal fittings. Make sure the fuel line is
secure and not near the exhaust or cylinder fins. While an inline fuel filter can be used, we recommend
filtering the gas entering the fuel tank from your field container.
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