O.S. 21XR-B Version II 1/8 scale Buggy Engine 1AW00

Ideal for up and coming 1/8 scale buggy racers and backyard bashers
Upgradeable with high performance O.S. Speed parts
Blue anodized aluminum cylinder head
Easy to tune 21J3-I slide valve carb with 7mm yellow restrictor for
more bottom end performance, and red 8mm restrictor for greater top
end speed
Natural finish crankcase

21XR-B Version II ABC Buggy Engine with Slide Valve Carb, 7mm & 8mm
Restrictors, P3 Turbo Glow Plug, Exhaust Seal Ring, two Dust Caps,
and 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, 2.42 HP/33,000RPM
Practical RPM Range: 4,000 - 40,000
Bore: 0.641" (16.27mm)
Stroke: 0.661" (16.8mm)
Weight: 13.40oz (380g)
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: Run vehicle with throttle fully open a few times over
long straight course to observe vehicle speed. Close needle valve
15° and repeat run. Gradually close needle valve in subsequent
runs to achieve highest speed taking care not to close needle
valve too far and overheat engine.

Metering Needle: With engine running, close throttle and allow
engine to idle for about 5 seconds then fully reopen throttle.
Turn metering needle clockwise 15-30° to lean mixture if
excessive smoke is observed, or counterclockwise 15-30° to
richen mixture if engine speeds up momentarily and then cuts out
abruptly.

Throttle Stop Screw Adjustment: Turn counterclockwise to reduce
throttle opening if engine runs too fast with throttle closed.