I'm planning to use a wide rear tire on an Egli-Type build and have been looking at ways to get adequate chain clearance.
The standard Egli, if there is such a thing, approximates the original Vincent engine mounting very closely.
The original Vincents have the engine mounted so that the crankcase joint, which I believe is also the lateral centre of the crankpin, about 9MM to the left of the centreline of the frame/wheels.
I suspect it would be ideal to have this joint right in line with the wheels so that the three really large heavy gyroscopes are all in alignment (2 wheels and engine crank).
For high speed handling it seems this arrangement would be optimal. Shifting the engine 9 MM to the right also gives another 9 MM of chain clearance which allows for 18 MM more tire width, good for my situation.
One other consideration is the lateral centre of weight of the engine. It would be ideal if the engine could be mounted such that the finished bike had its lateral balance line in the same postion as the wheel /frame centre line.
This doesn't necessarily mean there would be exactly the same amount of weight each side of centre as the balance point is affected by the position of the weight. In other words, there is a lack of total symmetry so simply having equal amounts of weight each side of centre is not the same as being balanced on centre.
A good starting point for this would be finding the lateral balance line of the engine and seeing how that relates to the centre of flywheels or if it is feasible to make the lateral balance line be the same as the frame/wheel centreline.
I'm posting this because I suspect others have already given consideration to these factors when building a Vincent Special.
I'll be happy if I can get this close. Being a very practical person, I'm quite willing to wear a second sock on one foot in order to achieve perfect balance
The standard Egli, if there is such a thing, approximates the original Vincent engine mounting very closely.
The original Vincents have the engine mounted so that the crankcase joint, which I believe is also the lateral centre of the crankpin, about 9MM to the left of the centreline of the frame/wheels.
I suspect it would be ideal to have this joint right in line with the wheels so that the three really large heavy gyroscopes are all in alignment (2 wheels and engine crank).
For high speed handling it seems this arrangement would be optimal. Shifting the engine 9 MM to the right also gives another 9 MM of chain clearance which allows for 18 MM more tire width, good for my situation.
One other consideration is the lateral centre of weight of the engine. It would be ideal if the engine could be mounted such that the finished bike had its lateral balance line in the same postion as the wheel /frame centre line.
This doesn't necessarily mean there would be exactly the same amount of weight each side of centre as the balance point is affected by the position of the weight. In other words, there is a lack of total symmetry so simply having equal amounts of weight each side of centre is not the same as being balanced on centre.
A good starting point for this would be finding the lateral balance line of the engine and seeing how that relates to the centre of flywheels or if it is feasible to make the lateral balance line be the same as the frame/wheel centreline.
I'm posting this because I suspect others have already given consideration to these factors when building a Vincent Special.
I'll be happy if I can get this close. Being a very practical person, I'm quite willing to wear a second sock on one foot in order to achieve perfect balance