Triumph Tigress TW2, Service Sheet

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250 c.c. O.H.V. TWIN CYLINDER SCOOTER
DISMANTLING FOR DECARBONISING
The term decarbonising means the removal of all carbon deposits from the combustion
chambers,piston crowns and ports. It is generally recognised as including attention to valves, guides
and springs. You will need these tools below. Most of which are easy to find or modify, except for
inlet valves and the steel gasket nowdays.
1. Top overhaul gasket set number 00-3120. 7. Valve grinding tool (suction type). 61-5035
2. Inlet valves number 76-60(2). 8. Valve grinding paste.
3. Exhaust valves number 76-61(2). 9. Scrapers for removing carbon.
4. Valve springs number 76-63(4) & 76-69(4). 10. Set of feeler gauges.
5. Valve guides number 76-15(4). 11. Supply of clean engine oil.
6. Valve spring compressor number 61-5001.
In order to carry out the work of decarbonising some dismantling is necessary and these instructions are
for the guidance of owners wishing to u ndertake this job themselves. Care should be taken to avoid damage
to nuts, bolts and other fixings by the use of incorrect tools , and as parts are removed the fixing bolts should
be replaced and the nuts just started so that they are not lost and to facilitate reassembly.
(a digital camera can be used to take pics as you go,this can be helpful when trying to relocate the
correct orientation of pieces,especially if the project stays apart for ages)
Before the engine can be dismantled it is necessary first to remove the dual seat and side valances. The
seat is held by two bolts and nuts securing " C" shaped brackets, and the side valances are secured by eleven
bolts, all of which must be removed together with the dual seat catch knob:
Detach the sparking plug leads and remove the cylinder head cowl and rocker cover. The cowl is held by
two nuts, one at each end of the cylinder head, and the cover by two nuts on top. Note that removal of the
cowl does not release the exhaust pipe flanges and that it is necessary to take off two further nuts securing
these flanges before the exhaust pipes can be moved away from the cylinder head.
There is no need to disturb the connection between the carburetter and its manifold. All that is
necessary is to take off the two nuts securing the manifold to the cylinder head and the carburetter can then be
moved sufficiently to one side to allow dismantling to proceed.
Slacken off the lower union of the rocker oil feed pipe and unscrew the upper union completely to allow
the pipe to swing out of the way.
Remove the sparking plugs and take off the seven cylinder head nuts. These nuts will require a small
cranked ring spanner to remove.
The cylinder head can now be taken from the block for decarbonising. This will reveal the cylinder head
joint face gasket which should be removed and examined. Replacement is generally desirable.
Removal of carbon is best done using a simple scraper, but it is important to avoid damage to the soft
aluminium cylinder head and piston crowns. Any marks on the joint faces will give rise to gas leakage and
may lead to further damage by burning after the engine is reassembled. To facilitate attention to the pistons
they should be turned to top dead centre (i.e. as far as they will come) and this position can be achieved by
engaging top gear and rotating the rear wheel.
nb:(try not to use a sharp metal scraper, a good plastic scraper will do now days,also still be careful not to
scratch the surface as the aluminium is soft)
Having removed all traces of carbon, carefully clean all parts with a slightly oiled rag, being sure to move
the pistons down the cylinders to enable carbon to be wiped from the top of the cylinder bores where it will
have gathered above the top piston rings.
The opportunity should now be taken to examine the valves, and for this to be done they must be
removed using Service Tool number 61-5001. The rockers need not be dismantled.
Be very careful not to lose the split collets, which will be released when the valve spring has been com-
pressed. It is a wise precaution to remove all the valves before continuing with any other work and to put
them together with their respective collets and caps carefully on a shelf or in a box, (or plastic zip bags can be
written on with cd marker pen) indicating from which positions in the cylinder head they were removed.