Whilst there are not any specific detailed plans you can download and build your CycleKart to, there are quite a few guidelines and sketches that can be used as a starting point. Ideally all CycleKarts are a unique expression of the owner, each individually crafted to mimic or be inspired from an inspiration car dating from the early part of the last century. However not everyone has an automotive manufacturing background or paid attention back in metalworking class at school, and so a basic generic chassis and drivetrain design that you can base your creation on is a good idea.
A CycleKart built to the Stevenson design using the MG P-Type as the tribute car
The classical CycleKart design is known as the 'Stevenson' design. This name is attributed to the guy(s) that originally created the design it and is the easiest style of cyclekart to build. It has straight chassis rails, welded together with a slight inward taper from the rear to the front. The passenger compartment is generally a plywood box that is bolts in-between the rails. The bodywork is an extension of this basic box in whatever style the owner is trying to achieve.
The classic 'Stevenson' Cyclekart design
Even if you are not building to the classic Stevenson design, the dimensions are still the same for all Cyclekarts, and so the plan shown above provide the perfect starting point from which to scale your build. By superimposing an image of your inspiration car over the top of it you will be able to take measurements and scale your chassis and frame layout from it.
More advanced Designs
There are also many variations on this basic design with profiled chassis and more ornate bodywork or construction techniques but the basic wheelbase, track and engine remains the same. There is no real limit to what else you can do as long as your CycleKart follows the basic specifications as detailed in the CycleKart Guidelines
Most people that are building a Cyclekart, overlay an image of their tribute car on top of the basic design blueprint above, so that they can scale the shape and dimensions of the body. You can find a step-by-step process of how to do this in the article "How to overlay an image of your tribute car"
You can find some additional plans and discussions on chassis design in the forums HERE
Generally CycleKarts are representation of actual cars from the period. However, CycleKarts that are not based on specific cars, but are constructed in the style of cars of the period are also fine. Any open wheeled car that fits in with the general aesthetic is perfectly acceptable
Further Examples
The following CycleKarts give you an idea of the diversity in styles and builds that you might see. All of these styles are acceptable under the CCA guidelines, which allow for any style of build as long as it fits the ethos of cyclekarting. There is even a new class of Cyclekart called 'Aerokarts' that have an extended wheelbase and aerodynamic styling.
This CK is called " Testarossa " ( Red Hen )
This CK is based on a Midget / Speedcar (popular form of racing up to the 70's in Australia)
Based on a traditional 1920's GN Cyclecar
An extended wheelbase Aerokart