O.S. 120AX Ringed w/Muffler

Tower Stock# LXLGJ0  •  Manufacturer Stock# 19210
O.S. 120AX Ringed w/Muffler (large view)
Notes from our tech department:
This is the O.S. Max Two-Stroke 1.20AX Ringed Engine with Muffler.

FEATURES

Model Application: Ideal for 3D, Precision and Sport flying
Mounting Application: Mounts in same space as the .91FX (actual
mounting dimensions vary slightly, see SPECS)
Internal Construction: Steel piston ring and liner, aluminum piston
Muffler: E-5020 "Power Box" with extension and 90 adapters
Carburetor: 70D with rearward angled needle valve for safety
Glowplug: O.S. #8 supplied with engine, A5 (OSMG2693) will also work
Warranty: Two-year limited

INCLUDES

O.S. Max Two-Stroke 1.20AX Ringed Engine with E-5020 Power Box
Muffler, #8 glow plug, muffler adapter, prop washer and lock nut,
needle valve extension cable,instruction manual and decal sheet,
two muffler screws, two muffler extension bolts, two long muffler
bolts.

REQUIREMENTS

Fuel: Two-Stroke with 18% lubricant and 5-20% nitromethane
Propeller: 15x10-12 or 16x8-10
Field Equipment: Glow starter, fuel filter, fuel pump, fuel tubing

SPECIFICATIONS

Displacement: 1.218 cu in (19.96cc)
Bore: 1.197" (30.4mm)
Stroke: 1.083" (27.5mm)
Practical RPM: 1,800 - 9,500 RPM
Power Output: 3.1 PS, 3.06HP/9000 RPM
Weight of engine: 29.0oz (823g) with muffler
Weight of muffler: 7.074oz (219.2g) with 90 adapter installed
Weight of muffler: 7.907oz (245g) with extension installed
Crankshaft thread size: 5/16-24
Distance Between Mounting Holes Same Side: 0.98" (25mm)
Distance Between Mounting Holes Opposite Side: 2.3" (58mm)
Distance Center of Crankcase to End of Crankshaft: 4.3" (109.5mm)
Distance Center of Crankcase to Drive Hub: 2.7" (69.8mm)
Width Between Mounting Tabs: 2.6" (67mm)
Width of Crankcase Below Mounting Tabs: 1.8" (46.5)
Length from Backplate to End of Crankshaft: 5.5" (139.9mm)
Length from Backplate to Drive Hub: 3.9" (100.2mm)
Height/Bottom of Crankcase to Top of Cylinder Head: 4.3" (109.2mm)
Height/Bottom of Mounting Tabs/Top of Cylinder Head: 3.4" (85.7mm)
Distance center to center of muffler mounting holes: 48mm (1.89")

Needle Settings: High Speed: 2 - 2.5 turns out from fully closed
Low Speed: 3/4 turn out from fully closed with the
throttle fully closed

COMMENTS

For version without muffler, order OSMG0651. The version without the
muffler does not include the muffler extension or the 90 adapter.
At this time one would not be able to use the muffler extension and
90 adapter at the same time. The long muffler bolts are too long.

jxs 10/25/05
Updated JBM 12-20-05
updt WM 11/29/05
ir/jxs
updt lmm 3/30/09

Resources
See Tower Catalog page 173.
Easy RC: Engines
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