O.S. 21XZ-B ABC Speed Spec II

Tower Stock# LXDCUD  •  Manufacturer Stock# 12175
O.S. 21XZ-B ABC Speed Spec II (large view)
Notes from our tech department:
This is the Speed Tuned 21XZ-B Speed Spec II ABC 1/8 scale Buggy Engine
from O.S. Engines.
******Because of the expressed racing nature of this engine,******
******it is NOT covered by the O.S. 2 Year Warranty******
******per page 1 of manual.******


DLC coated crankshaft with silicone filled intake passage for
improved fuel flow
ABC piston and liner construction "A"luminum piston fitted to a
"B"rass cylinder liner that is "C"hrome plated
21J2(B) slide valve carburetor with three carb reducers that restrict
airflow helping to increase the amount of torque produced
Black anodized crankcase
Ceramic rear ball bearing


21XZ-B ABC Buggy Engine with Slide Valve Carb, P3 Turbo Glow Plug,
Exhaust Seal Ring, two Dust Caps, Instruction Manual and 6mm, 6.5mm
and 7mm Carb Reducers


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


Displacement: .213 cu in (3.49cc)
Output: 2.65 PS, 2.61 HP/34,000RPM
Practical RPM Range: 4,000 - 42,000
Bore: 0.641" (16.27mm)
Stroke: 0.661" (16.8mm)
Weight: 12.52oz (355g)
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: 3.4" (86.5mm)
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 Crankshaft to Front Bearing: 1.7" (44mm)
Distance from Center of Crankshaft to Backplate: 0.81" (20.5mm)

Carburetor Settings, NOTE carburetor is preset at factory and
requires very small adjustments
Needle Valve: Approximately 3.5 turns open from fully closed
Throttle: Approximately 0.5mm open from factory setting with
reducer removed
Metering Needle: Rotate until slotted head is 1.5mm away from ball
link body
Mixture Control Valve: Rotate until slotted head is flush with
carb body

jxs 02/25/13

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