O.S. 21XZ-R VII On-Road .21 Engine

Tower Stock# LXBCBL  •  Manufacturer Stock# 13875
O.S. 21XZ-R VII On-Road .21 Engine (large view)
Notes from our tech department:
This is the O.S. 21XZ-R Version II ABC Engine with 21M Carburetor
for 1/8 scale On-Road Vehicles.

****** Because of the expressed racing nature of this engine, ******
****** it is NOT covered by the O.S. 2 Year Warranty ******
****** per page 8 of manual. ******


Tungsten-weighted silicone filled crankshaft creates optimum balance
for consistent low and mid speed torque
ABC piston and liner construction "A"luminum piston fitted to a
"B"rass cylinder liner that is "C"hrome plated
Liner has seven scavenger ports and three exhaust ports for more
efficient combustion
21M slide valve carburetor with 9mm carb reducer that restricts the
airflow helping to increase the amount of torque produced


O.S. 21XZ-R Version II ABC On-Road Engine w/21M Carburetor, Exhaust
Gasket RP7 Turbo Glow Plug, 9mm Carb Reducer, Flywheel Collet,
Instruction Manual, 0.2mm Head Gasket and two Dust Caps


Fuel: 10-30% nitro content, 20% recommended for break-in
Exhaust System: Depending on vehicle
Glow starter, fuel tubing and track equipment


Displacement: 0.213 cu in (3.49 cc)
Bore: 0.640" (16.27 mm)
Stroke: 0.661" (16.8mm)
Practical RPM: 4,000-45,000
Power Output: 2.75 PS, 2.71 HP @ 33,000 RPM
Weight: 12.06oz (343g)
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: 3.45" (87.7mm)
Width of Mounting Tabs: 1.8" (45mm)
Distance from Backplate to Front Bearing: 2.6" (65.6mm)
Distance from Center of Crankshaft to Front Bearing: 1.7" (44mm)
Distance from Center of Crankshaft to Backplate: 0.85" (21.6mm)
Carburetor Settings,
Needle Valve: Approximately 3 turns open from fully closed
Throttle: Approximately 0.5mm open from factory setting with
reducer removed
Metering Needle: Rotate until slotted head is 0.5mm away from ball
link body
Mixture Control Valve: Rotate until slotted head is flush with
carb body

jxs 07/25/11

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