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:
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:
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:
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