Original Year
# of pieces
Other:  Motorcycles
Steering, kickstand, V-2 engine
front and rear suspension
Other Views

8422 Circuit Shock Racer

iso revolve
Click the image to download the LDraw file of this model.
Model by Benjamin Wendl

Set 8422, released in 1995, was similar in function to the previous motorcycle 8838 but represent more of a road bike instead of an off road or dirt bike.  It still features a steerable fork, kickstand, front and rear suspension, and a chain driven V-2 engine.  It also has a front fairing and windshield and what appears to be a luggage container behind the seat.

Although at first glance it appears that this model is build with many odd angles, the main body is in fact built mainly on traditional studs.  The entire body is then tipped at an angle when mated to the suspension assemblies.  The gas tank is built of angles using liftarms, triangles, and rotors.

This model uses the same wheels as the previous motorcycle, but adds new smooth tires which appear only in this model.  If you look closely, you will see that the revolving animation actually uses the wrong knobby tires because the correct tires do not exist in LDraw.  I actually like this look because it resembles a BMW dual-sport bike.


The front fork can be steered using the handle bars which are constructed of toothed connectors and axle pins.  The fork pivots around an axle which passes through the head tube part.  A pair of triangle parts are used as triple trees.  The handlebar angle is fixed using toothed connectors.  The fork rake angle is set by the head tube.  The telescopic fork tubes are made from the shock absorber elements.

A close look will reveal a brake rotor on each side of the front wheel.  No caliper for it though.

There are a pair of printed front headlights, a fairing, and a simulated windshield.
steering     steering
Click for an animation of the steering in motion.
The V-2 engine is located in the frame under the fuel tank and is mounted laterally.  It is coupled to the rear sprocket via a chain.

The engine is made from cylindrical engine elements and is driven by the rear wheel.  The 24 tooth sprocket on the wheel is connected to a 16 tooth gear on the transmission.  A pair of 24 and 8 tooth gears further change the ratio.  Finally, a pair of 12 tooth bevel gears turn the torque at a right angle and into the crankshaft.   The crankshaft is offset 1/2 stud from center, giving the pistons a stroke of 1 stud.

The final gear ratio is (24:16) * (24:8) = 4.5:1.
engine     engine
Click for an animation of the engine in motion.
The side stand can be retracted on a friction pin although at full retraction it interferes with the chain.  At full extension it is stopped by an axle pin.

I didn't make an animation of the kickstand, but I bet if you are really intelligent you can figure it out.
This model has both front and rear suspension.  The layout is very standard for this type of motorcycle.

The rear suspension uses two shocks running from the seat down to a point just above the rear wheel axle.  The trailing arm pivots on the rear transmission axle, which also rotates with wheel motion.  The shocks bottom out at about the same position as the tire hits the bottom of the seat.

The front suspension is a conventional telescopic fork type.  Compressing the front shocks by putting weight on the seat puts a lot of stress on the head tube part due to the rake angle.
suspension    suspension
Click for an animation of the front suspension in motion.
Click for an animation of the rear suspension in motion.
Wheels and Tires
This set uses two 6 spoked white motorcycle wheels and the new smooth tires which are unique to this set.

Other Views

Side View
side view
Top View
top view
Front View
front view
Back View
back view
Computer Render

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