Triumph Tigress TW2, Сервисная ведомость

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Service Sheet No. 1002 (contd.)
Scrape all carbon from the inside of the ports, (i.e., the passages in the cylinder head which allow the
entry and exit of gases.) Take care to avoid damage to the seats. (These are the angular faces in the
cylinder head, which, when mated with similar seats on the valves, provide a gas-tight seal.) Clean up the
valves by careful use of fine emery cloth.
Unless the engine has covered a considerable mileage, it is unlikely that anything but a simple grinding in
operation will be necessary to restore the valve seats to perfect condition. Valve grinding is done by smearing
a small quantity of grinding paste (obtainable from any Dealer) on the valve faces, re-inserting them into their
guides and rotating backwards and forwards. The valve should be moved round to a new position after every
few movements. This should not be overdone , or in time valve pocketing, with
consequent lack of efficiency, will develop.
If considerable pitting of the seats is evident they must be recut and the valves either reground or
replaced. This is best left to a Dealer, who will have the necessary service tools. This you do have to be
careful with.
Before reassembling, clean off all traces of paste and smear the parts with clean engine oil.
Reassembling is undertaken in the reverse order, but note should be taken that it is a wise precaution to
replace valve springs when decarbonising. They are not expensive and replacement will help to maintain
the efficiency and performance of the engine.
The part numbers of the valve springs are 76-69, 76-63, inner and outer respectively. When refitting
valves particular care should be taken to ensure that the collets are correctly seated.
The cylinder head holding down nuts should always be tightened in the order shown in Fig. 1, and each nut
must be pulled down a little at a time to avoid distorting the head.
Fig. 1.
Cylinder Head Nut Tightening.