O.S. 21XR-B (P)

Tower Stock# LXCWGL  •  Manufacturer Stock# 12200
O.S. 21XR-B (P) (large view)
Notes from our tech department:
This is the 21XR-B (P) 1/8 scale Buggy Engine from O.S. Engines.

**Not covered by the O.S. Two Year Warranty.**


Shares the same basic layout as the O.S. 21XZ-B and can be upgraded
with 21XZ-B parts
Ideal for up and coming 1/8 scale buggy racers and backyard bashers
Blue anodized aluminum cylinder head
22(B) slide valve carburetor
Natural finish crankcase


21XR-B ABC Buggy Engine with Slide Valve Carb, P3 Turbo Glow Plug,
Exhaust Seal Ring, two Dust Caps, Instruction Manual


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: 2.45 PS, 2.61 HP/33,000RPM
Practical RPM Range: 4,000 - 40,000
Bore: 0.641" (16.27mm)
Stroke: 0.661" (16.8mm)
Weight: 13.5oz (370g)
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 02/28/13

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