T5 motor is a legend, lovely clean bikes you have there, immaculate individuals which have had a lot of labour loved on them is clear to see, and very understated to the untrained eye.
Is the 172 motor spec the same on each of them ? What sort of performance do you experience with them, what of your choice of carb, pipe, gearing....please tell
Can I ask of the seat on the red bike, and where you got it, I had the same on my Polini T5, great seat that helped get me behind my Driver screen on the day
Lovely stuff