Barrels & Pistons

Let's have a look at the barrels and pistons again. some time back we had a preliminary look, but since everything is apart now we can make a more thorough examination and dimensional survey.

Armed with a bore gauge and a micrometer, we can do some measurements:

Parameter Transverse = parallel to crankshaft axis Longitudinal = parallel to motorcycle axis	Dim’n	Wear	Data Source	Position Number 1 – Drive side Number 2 – Timing Side
				Number 1	Number 2
Cylinder Bore upper transverse ¼” down from gasket face				2.821”	2.819”
Cylinder Bore upper longitudinal (A) ¼” down from gasket face				2.817”	2.817”
Cylinder Bore middle transverse 1” down from gasket face				2.816”	2.815”
Cylinder Bore middle longitudinal (B) 1” down from gasket face				2.813”	2.815”
Cylinder Bore lower transverse 2” down from gasket face				2.816”	2.816”
Cylinder Bore lower longitudinal (C) 2” down from gasket face				2.811”	2.813”
Piston (ring land area longitudinal) (A1)				2.793”	2.792”
Piston (ring land area clearance) (A-A1)				0.024”	0.025”
Piston (below rings longitudinal) (B1)				2.811”	2.812”
Piston (below rings clearance) (B-B1)		0.002” 0.004”	BSA Service Sheet 216	0.002”	0.003”
Piston (Extreme Skirt longitudinal) (C1)				2.813”	2.813”
Piston (Extreme Skirt clearance) (C-C1)		0.002” 0.004”	BSA Service Sheet 216	-0.002”	0.000”

All the rings were stuck so the pistons are away for a well earned soak in the parts washer. I'll leave this picture here so I don't forget where they are: