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O.S. - OSMG2051 OSM12186 12186 531028020955 4531028020955
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O.S. 21XZ-B Speed ABC w/21J2(B) Carb
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O.S. 21XZ-B Speed ABC w/21J2(B) Carb
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Tech Notes
This is the O.S. 21XZ-B ABC Engine with 21J2(B) Carburetor
for 1/8 scale Off-Road Buggy Racing.
****** 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. ******


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
Three port cylinder liner with special Speed version inner head and
porting for smoother acceleration
21J2(B) slide valve carburetor with 6, 6.5 and 7mm carb reducers
that restrict the airflow helping to increase the amount of torque
Black anodized crankcase with ceramic ball bearings helps reduce
resistance and increase performance


O.S. 21XZ-B ABC Off-Road Engine with 21J2(B) Carburetor, Exhaust
Gasket, P3 Turbo Ultra Hot Glow Plug, 6, 6.5 and 7mm carb
Reducers, Instruction Manual 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: 0.21 cu in (3.49 cc)
Bore: 0.6" (16.3 mm)
Stroke: 0.7" (16.8mm)
Practical RPM: 4,000-40,000
Power Output: 2.6 PS, 2.56 HP @ 34,000 RPM
Weight: 12.5oz (355g)
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" (86.3mm)
Width of Mounting Tabs: 1.8" (45mm)
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 11/23/10

– If you need more information, use these O.S. resources –
Email: enginesupport@hobbico.com
Web Site: http://www.osengines.com/
Phone: 217-398-8970
  Postal Address:

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Accessories Needed
This is the O.S. 21XZ-B ABC Off-Road Buggy Engine with 21J2(B) Carburetor. FEATURES: Tungsten weighted silicone filled crankshaft, slide valve carb w/6, 6.5 & 7mm reducers, P3 turbo ultra hot glow plug and instruction manual, manual, black anodized crankcase w/ceramic ball bearings REQUIRES: Fuel, air filter, exhaust system, track equipment

Accessories for the O.S. 21XZ-B Speed ABC w/21J2(B) Carb

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 LXRXC9 Tower Hobbies TOWER Power 20% Car Fuel Quart
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