The motorcycle design is not less exciting than any other vehicles. Besides the motorcycle, which are, in fact, the bare concept of a self-propelled mechanism, requires greater design sophistication, inventive gift and sense good mechanic. Offer the reader the court their ideas on how to design a homemade motorcycle. I can say that some experience in this kind of work I have: in the competition “Motosam-90” was presented to my homemade — eighth — motorcycle in the picture that readers can see the report from the review in No. 2, 1991. The photographs presented on these pages, three motorcycle my design. One of them is the latest and most successful — I want to tell the readers.
For thirteen years I designed and built twelve two-wheeled machines. They all differed significantly from each other. And two motorcycles were designed using a partial schema of the monocoque, and three completely frameless, with a monocoque housing-a monocoque. That was the design I prefer: it seems to me the most reliable and advantageous from the standpoint of strength, weight and ergonomics.
I hope that my engineering experience can be useful for those who are going to do the bike.
So, what is a conventional bike frame design? Simplifying the answer, we can say that this frame, fuel tank, tool boxes, the housing Vozduhoflotsky with the muffler inlet, muffler noise issue, rear fender with bracket tail light and rooms, the base of the seat, the trunk, and pounds of all kinds of bolts, nuts, bushings, pins, washers, and rubber bands, with which all of the above combine in a single structure.
If the sum of the masses of these components, you get a very impressive amount. Besides collected all this together forms not aesthetically pleasing “skeleton” having a lot of secret places where she will inevitably meet brand heels the dirt — to get rid of it it is possible only by completely dismantling the bike.
After a year or two — and begin to rattle tool kits, creep cracks on the rear wing falls off with a bracket… And if the motorcyclist, God forbid, gets at least a slight accident, or even simply falling? In these cases, the frame is bent, dents on the tank and tool boxes. Even more trouble delivering huge lower silencers, clinging to the corners even over smooth asphalt and significantly reduces the passability on bad roads.
All of these deficiencies deprived the two-wheeled machine, designed according to the design scheme of “monocoque”. This bike is a monobloc welded box design that performs the functions of all the above listed parts and assemblies. Interestingly, the spatial box construction is substantially more rigid and durable than the classic frame (including the duplex frame). Use diagrams of “monocoque” in the motorcycle design not only reduces weight two-wheeled vehicle, but the closer to the earth, the center of gravity of the motorcycle. This happens due to the fact that in such construction the tool kit and battery compartment are located at the bottom of the housing, and a light vostokfilm with the muffler inlet is at the top where classic motorcycle is fuel cap. The air intake is above the steering column in the area the cleanest, dust free air. Inside the monocoque and may be a muffler issue, however, should be provided with reliable insulation from the fuel and the cushion of the seat.
Fig. 1. Motorcycle type
Fig. 1. Motorcycle type “Enduro” with a body monocoque construction L. Garagashian:
1 – rear view mirror, 2 — hidden tube fuel tank, 3 — the compensation chamber of the shock absorber, 4 — absorber with stroke PI Oka 120 mm, 5 — swinging lever 6 —pushing arm 7, the brake rod 8 — rear part of the body with the muffler issue (s l e in a) and oil tank (Ref a), 9 — rear turn signal, 10 — lamp for Parking light and brake light (dual), 11 — exhaust pipe (l e a), 12 — brake disc, diameter 300 mm, 13 — “the trap” chain, 14 — sprocket of the rear wheel (/==37), 15 — pendulum suspension of a back sprocket, 16 —sprocket (g=15), 17 — pedal foot brake, 18 — lever sets gearbox, 19 — drum winch, 20 — muffler – resonator, 21 — guided bracket wire rope hoist, 22 — disc front brakes diameter of 300 mm.

Fig. 2. The layout of the case is monocoque. The value of a cell of the grid is 100x100 mm.
Fig. 2. The layout of the case is monocoque. The value of a cell of the grid is 100×100 mm.

Fig. 3. The most rational scheme of the welds used in the Assembly of the body-monocoque
Fig. 3. The most rational scheme of the welds used in the Assembly of the hull is monocoque.
In figures 1 and 2 — my motorcycle “Enduro” and its body-monocoque with rear suspension and protective frame of the engine. The weight of the monocoque is only 23 pounds, and the useful volume of such a body is about 56 litres, including fuel tanks have 41 l (greater than the “Lada”!), is fully used and the remaining volume of the housing. The bike does not look bulky. On the contrary, it has relatively small dimensions, in particular, the base machine is only 1350 mm (less than any of the Izhevsk motorcycle).
I must say that you can make a case-monocoque is no more difficult than to cook a good frame and equip it with all hinged parts. It is only necessary to strictly adhere to a previously developed technology, so all the details are well docked and they would be comfortable welding.
Drawing the design of the case, be sure to provide a convenient landing of the driver — this is especially important for motorcycles such as “Enduro”— as well as the safety of the movements of the rider, comfort of motion in the sitting position, in front and behind.
After selecting the optimal, in the opinion of the designer, the layout should draw the whole motorcycle life-size — to depict the side view, top, front and rear, as well as to trace the most characteristic section. The more detailed drawing documentation, the easier it will go further work on the production of two-wheeled machines.
The engine is rationally placed directly on the axis of the pendulum. The reaction from the tension of the drive chain snaps directly on the pendulum. And she is not small — sometimes reaches the tensile strength of the continuity, that is nearly two tons! To mount powerful and not too well-balanced engine “IZH-the planet” (and all cross motors) must use the silent blocks or rubber cushions. It is only necessary to consider that the chain not only pulls the engine backwards, but also expands it in the horizontal plane due to the asymmetric arrangement of the circuit.
In the work to create the body and monocoque is very convenient to use the method of volumetric modeling. While the mA-‘ ket housing is assembled from cardboard blanks which are joined with strips of paper and glue. In the manufacturing process layout, typically there is a change in hull design, because not everything can be provide in drawing flat projections. In conjunction with prototyping case it is desirable to examine the routing of its Assembly — this will ensure ease of welding. You must take into account a possible warping of the metal workpieces during welding of the case under uneven heating. Keep in mind that the details, which are mounted on the pendulum and the steering column is welded last. If necessary to make them fit to the body in order to ready the bike to the plane of the wheels coincides with the plane of symmetry of the hull-monocoque.
The finished volume layout is cut at the splice, and cardboard patterns of the elements of the monocoque are numbered: according to these patterns will be stripped of blanks from sheet steel of appropriate thickness from 1.2 to 1.5 mm. the easiest way to do this using a chisel on a massive anvil.
Welding should be done in strict accordance with the technological map. The seams looked clean and solid, edges of the welded parts should be slightly bend, as shown in figure 3.
To ensure sufficient strength of the body, the monocoque is appropriate in its design to introduce additional amplifiers, flanging, stiffeners. For example, the steering column on my motorcycle and the crossbeam stiffness, which is welded to bracket a single rear shock absorber, additionally connect steel pipe rectangular 25×40 mm. everything inside this pipe is convenient to place the wiring and control cables, motorcycle.
The design of the silencer inlet significantly affects the engine power and its torque characteristic. The greater the volume is, consequently, easier “breathing” of the engine, the less ripple of the air in the filter, and hence less noise. Experts recommend to lay the value of the volume of the muffler is not less than 20 working volumes of the engine. Tract from Vozduhoflotsky to the carb must be smooth to avoid the turbulence of the air flow, which can significantly reduce the power of the motor.
After welding the case is monocoque checked for leaks, first by water and then clean gasoline. In the absence of leaking welds from the inside of the liquid promazyvaetsya with epoxy — it will fill the fine pores, will connect the pieces of slag and metal droplets is particularly important for the silencer inlet.
Rear suspension — pendulum type, with the cantilevered mounting of the wheel. Wheel travel around 260 mm. Joint pendulum ball-bearing with seal a seal. The chain tension using quick release lever. The disc brake has a mechanical drive.
Front suspension — on the basis of the plug from the motocross bike СZ-516. The wheel under the tire and 21 inch wheel drive brake disc brake pads — hydraulic.
Soft cushion seat is attached directly to the chassis-the monocoque, and the case made of artificial leather attached to it with screws wpoty.
I would like to warn readers who do not have sufficient experience in the construction of motor transport that the creation of a homemade two-wheeled machines — it is very complicated. In this article, I tried to talk about his work and the ideas I think are promising for Amateur motorcycle. However, novice Motostroitel I would strongly advise you not on the basis of the material taken for the creation of powerful machines. It may be better to start with motorcycles easier. I went to the monocoque, creating more than a Dozen intermediate designs…
Alex GARAGASHYAN, s a n K t-P etersburg

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