Single cylinder and multi-cylinder balancing

[Fabian]

I've seen this topic covered so many times yet there has never been any formal and in depth technical information presented, that takes out the mystery and inserts maths.

Video tutorial:



Single-Cylinder Engine Balancing:





V & Radial Engine Balancing:





In-line Engine Balancing:

 

[Lee_K]

I remember studying this very subject in college (44 years ago). I never did get a good grip on balancing reciprocating masses. But I know single cylinder engines can not be perfectly balanced at all speeds, engineering always involves compromise. Good engines designed and built by good engineers have been through this analysis. Good engines will still shake, but someone has put lots of effort into getting it under control.

Many years ago I had a 350 single cylinder Ducati motorcycle. It vibrated so bad between 4000 and 5000 rpm that you could not stand it. Rev it faster or slower and it was OK. They could have done a lot better with this engine.

 

[Fabian]

That's why you add another cylinder to a single cylinder engine at 90 degrees - why won't the Chinese learn this simple lesson and manufacture a 90 degree v-twin for our bicycles, though i wouldn't mind seeing a parallel twin cylinder bicycle engine with a non planar crankshaft i.e. half cruciform crankshaft arrangement, like a Yamaha TRX 850.

 

[LewieBike]

I owned a ducati 250 bevelhead, it was pretty smooth for a single 4 stroke of it's vintage.

 

[Deleted member 12676]

when I clicked to see the first video I was presented with the words "this video does not exist"

 

[Fabian]

The link has changed: