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Motoczysz C1 - analysis

C1 is a very interesting motorcycle from a newly founded company with the weird name Motoczysz.This article is focused in the areas that C1 has the most unusual design choices, the engine and the suspension and it is based in images drawings and data provided from the official website.

The engine is essentially two in-line bicylinder engines joint (also in-line) but with counter rotating crankshafts. It is like having an in line four cylinder engine positioned lengthwise (like some older Indians or the 3 cylinder Triumph Rocket III) but with half of the engine rotating with the opposite direction than the other half.
This layout has the advantage that the engine does not influence gyroscopically the attitude of the bike, which is a problem in motorcycles with lengthwise positioned engines, and also the bike can be very thin, almost as thin as a V-2.However there are the following problems:

-It doesn't positively exploit the gyroscopic influence of the engine like a transversally mounted engine (whatever the number of cylinders).This gyroscopic influence is strong when the crankshaft is rotating in the same direction with the wheels and it tends to stabilise the bike. However some engineers prefer a more agile handling and position the crankshaft to rotate in the opposite direction thus eliminating the gyroscopic effect (ex yamaha M1 of 2004/5).

-Although with the two counter rotating crankshafts the main vibrations and the gyroscopic effect are eliminated there should be a weaving motion introduced by the engine because every one of the two 'halves'' of the engine is located in a different plane lengthwise. That weaving may be annoying for the ride or even dangerous if not taken into consideration at the overhaul design.

-The internal friction and losses should be considerably more in comparison to a classic in line four although the two crankshafts may be lighter than the one of an 4cyl engine because of their shorter length.

-The engine is very tall because its length dictates the gearbox to be positioned below it and the clutch just behind the front wheel. The angle of 15 degrees that the two parts of the engine are relatively positioned should have been selected for packaging reasons because the two crankshafts could be geared in any desirable angle with no vibration problems. A similar solution in the general idea is selected in the Honda V2 with 52 degrees angled cylinders. There the crankpin of every cylinder is position in diffirent azimuth angle in the crankshaft to emulate the timing of a V-2 with 90 degrees angled cylinders and reduces vibrations.

A 2 crankshaft engine is not a new idea, on the multicylinder 2-stroke motorcycle engines it is a very common layout.
However here it may mostly be selected for recognisability and diversion but it is nevertheless and interesting and by no means an inferior design, it will prove its value in practise.

The suspension design front and aft is also very interesting although it is not as exotic as a first glimpse may suggest. The front fork may look like a four link design like that of BMW-duolever/Hossak or that of the late Britten's motorcycle but it isn't.

It is essentially a telescopic fork but the difference is that both the spring and the damper are located at the steering head and the fork is just a slider .
The result is a structure that is identical as a principal of function with the classic telescopic fork but with the spring/damper externally linked. There are some advantages here, the spring/damper doesn't contribute to the unsprung weight and they doesn't impose structural or design limitations because they are mounted externally to the fork. Also the fork sliders can be calculated to flex different according to the direction of the load thus enhancing handling especially in high lean angles when cornering. A similar system had been presented in the past from hyper-pro.

The rear suspension does not have something revolutionary, its weird design is dictated by the very long engine and the lack of space that impose. The damper is mounted in the usual position with a floating linkage but the springs (two smalls instead of a bigger one) are located in the sides (supported by sliders) in order to leave space for the exhaust pipes and the engine between them. A similar system is used from the Suzuki TL-S/R motorcycles because of shortage of space but also because the rotary damper cannot be placed cocentrically with the spring as the telescopic ones.

Over C1's stickers is written "american motogp project", it would be interesting this very different motorcycle to find its way to MotoGPs and to see if all this lateral thinking will pay off in the race track.

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(article update 190605)


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I.K.Erripis 100605

BMW's duollever front system

The rear suspension of Suzuki TL S/R with rotary damper and the spring supported from a telescopic slider.

The Triumph RocketIII with in line 3 cylinder engine.

The engine of Bimota V-due with two crankshafts.

Hyper-pro's alternative front system, similar in principle with the telescopic fork but with externally mounted springs and dampers.

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