The most important part of any motorcycle is its frame. It's the frame that defines the silhouette of a motorcycle (not just custom), and therefore its appearance. It depends on the frame, which type of motorcycles your Dnipro will belong to after the modification: chopper, classic, enduro or sports bike. All this is of course relative, because I think you can only build a chopper from Dnipro.
So before you is a washed frame of "Dnipro". What can be made of it? And you can do a lot of things, especially if you cut it completely into pipes. But this should be seen as a new frame, not a remake. Modification involves relatively little interference with the structure.
The most popular modifications to the frame are:
Rear frame extension (behind the engine). Allows you to increase the space for the driver's feet. Usually the frame is lengthened by 5-15 cm with the corresponding extension of the cardan shaft. The degree of extension usually depends on the height of the biker.
Front frame extension (in front of the engine). Allows you to implement the "American landing" with an opposing engine. In this case, the controls of the braking system and gearbox are transferred to the rod located in front of the engine at a height that is selected individually for the height and length of the driver's legs. This is the principle implemented at the Russian Ural-Volk. I should note that the height of "pedals" on this motorcycle is chosen approximately and on average. As a result, the driver's legs are unjustifiably "lifted" upwards.
In case of front frame extension, the standard length of the PTO shaft is usually used.
Frame extensions. Used to install the thicker rear wheel. Experience has shown that it is possible to install the rear wheel no more than 200-210 mm wide. For thicker wheels, either a broken PTO shaft with intermediate bearing or a gearbox can be used to shift the output of the PTO shaft to the side.
Actually, it is possible to put a wheel no more than 120 mm wide in a standard Dnieper pendulum. In this case, there will be a gap of about 3-5 mm between the tyre and the cardan. I consider optimal a small expansion of the frame and pendulum for the installation of the wheel width of 130-150 mm. It is with this width of the wheel that the modification will have optimal driving characteristics.
Changing the angle of inclination of the front fork. Very popular and ambiguous modification. It is necessary to know, that the increase in the angle of inclination of a fork more than 33 degrees entails a strong deterioration of controllability of a motorcycle (it is connected with the general geometry of a motorcycle and is described in textbooks and some popular motor-journals).
Also, the increase of the inclination angle strongly loads the standard Dnieper feathers of the fork and leads to their rapid failure. Also, according to personal experience, I have repeatedly observed cracked traverses and upper tubes of the frame. Therefore, I try not to use the increase of the angle of inclination of the front fork (33 degrees - maximum) in my designs.
Tilt of rear shock absorbers. It is used for their more efficient operation and improvement of the design appearance (according to many people, vertical Dnieper shock absorbers do not look aesthetic).
It should be taken into account that the inclination of the rear shock absorbers should be optimally selected, because with a significant increase in the angle of inclination of the standard Dnieper shock absorber, the load capacity of the motorcycle is greatly reduced. This can lead to the fact that even a ride with a compact passenger will not be possible.
Various smaller refinements:
- Mounting the cups under the taper bearings of the front fork. Very useful refinement, but requiring the production of new crossheads.
- Undervalued saddle line. Usually used for frame extension.
- Front frame enlargement is done by extending the front pipes. And so on.
Now you know what frame you need and you can start cutting the standard Dnieper frame. Here it is necessary to be guided by the principle "measure seven times, cut once".
Dnipro" frame is made of solid steel pipes with a wall thickness of 3-4 mm. These pipes are perfectly welded by electric welding. But welding of frame pipes has the features.
The main task is the strength of the weld. It is checked that even in case of accidents well welded pipes never burst at the welding site. Therefore, before starting to work with the frame, it is necessary to make sure that you have sufficient ability to work with electric welding. It is advisable to train on pipes similar to those used in the frame. Actually, all the pipes have various elongation and dovarok desirable to take from another frame.
It is extremely undesirable to use water pipes, as they are sutured and their strength is much lower. In addition, the diameter of water pipes does not correspond to the diameter of pipes of the Dnieper frame.