O.S. Speed 21ZX-B Spec II Ty Tessman 110% Engine

Tower Stock# OSMG2037  •  Manufacturer Stock# 1217D
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Notes from our tech department:
This is the O.S. Speed 21XZ-B Spec II Ty Tessmann Edition 110% Long Stroke
Glow Engine O.S. Engines.


0.16" (4mm) lower cooling head lowers center of gravity for improved
21J3(B) slide valve carburetor with 7mm carb reducer that restricts
airflow helping to increase the amount of torque produced


21XZ-B Spec II Ty Tessmann Edition 110% Long Stroke Glow Engine with
Exhaust Gasket, P3 Turbo Ultra Hot Glow Plug, 7mm Carb Reducer,
Decal Sheet, two Dust Caps and Instruction Manual


Glow Fuel: 10-30% nitro content, 20% recommended for break-in
Tuned pipe such as the O.S Engines T-2090SC, OSMG2953
Glow Starter and Track Equipment


Displacement: 0.213 cu in (3.49 cc)
Bore: 0.641" (16.27mm)
Stroke: 0.661" (16.8mm)
Practical RPM: 4,000 - 42,000
Weight: 12.45oz (353g) engine only
Crankshaft Size: UNF1/4-28
Distance Between Mounting Holes Same Side: 0.83" (21mm)
Distance Between Mounting Holes Opposite Side: 1.45" (37mm)
Height Bottom of Mounting Tabs/Top of Cylinder Head:
Width at Mounting Tabs: 1.8" (45mm)
Width of Crankcase below Mounting Tabs: 1.2" (31.6mm)
Distance from Backplate to Front Bearing: 2.5" (64.5mm)_
Distance from Center of Crankcase to Front Bearing: 1.7" (44mm)
Distance from Center of Crankcase to Backplate: 0.81" (20.5mm)

Carburetor Settings, NOTE carburetor is preset at factory and
requires very small adjustments
Needle Valve: Approximately 3 turns open from fully closed
Throttle: Approximately 0.5mm open from factory setting with
reducer removed
Metering Needle: Flush with ball link body
Mixture Control Valve: Rotate until slotted head is flush with
carb body

jxs 07/28/17



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