Triumph Trident T160 - B22 INSPECTING THE PISTONS AND CYLINDER BORES; B23 TABLE OF SUITABLE REBORE SIZES

ENGINE B
SECTION B22
INSPECTING THE PISTONS AND CYLINDER BORES
PISTONS
Check the thrust areas of the piston for signs
of seizure or scoring.
High spots, leading seizures, are Indicated by bright
patches and scoring, following a seizure, Is shown
by deep scratches and Injury to the surface of the
piston. High spots may be removed with a few
strokes of a fine file. Sometimes, following a
seizure, the rings become trapped and again careful
action with a file or scraper is required to release
them.
The piston skirt Is of a special oval form and Is
designed to have limited working clearance within
the bores. The clearances are given In GENERAL
DATA, page. GD4.
Prior to Inspection, ensure that both the cylinder
bores and pistons are clean and free from dirt,
etc. Any deposits of burnt oil round the piston
skirt can be removed by using a gasolene (petrol)
soaked cloth.
NOTE: The top lands on pistons have a
greater working clearance than that at the
skirt and thus allow the top piston ring
to be viewed from above, and the piston to be
rocked slightly. However, this is not criti.cal;
it is the skirt clearances that are all important.
CYLINDER BORES
The maximum wear usually occurs within the top
half Inch of the bore, whilst the portion below the
piston ring working area remains relatively unworn.
Compare the diameters, measured at right angles to
the wrist (gudgeon) pin, to obtain an across the
thrust faces, I.e. estimate of the wear. A difference
between these figures In excess of .005 In. (.13 mm.)
Indicates that a rebore Is necessary. Compare the
figures obtained with those given below so that
accurate information for the actual wear can be
obtained.
An approximate method for determining the wear
In a cylinder bore Is that of measuring the piston
~ ring gap at various depths In the bore and comparing
with the gap when the ring Is at the bottom of
the cylinders. The difference between the figures
obtained, when divided by three (an approximation
of IT) equals the wear on the diameters. As above,
if the difference exceeds ·005 In: (·13 mm.), this
Indicates that a rebore is necessary.
SECTION B23
TABLE OF SUITABLE REBORE SIZES
Piston size
IBore
Size
Ins. (mms.)
I Ins.
mms.
Standard
Max. 2·6366 66·970
Min. 2·6355 66·942
+0.010 (0.254 mm.)
2·6466 67·224
2-6455 67·196
+0.020 (0.508 mm.)
2·6566
67·478
2·6555 67·450
+0.040(1.016 mm.)
2·6766
69.986
2-6755
67·958
NOTE: Standard cycllnder blocks are marked on the upper fin with the lecters H, M or L as a
production facility. These symbols should be removed by fding when a block h,.s been re-bored.
The recommended piston clearance Is given In General Data, page GD4.
B25
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