The Mordern Bajaj Chetak Rides One
As written by bajajusa's former president:

Here is the proper and detailed procedure for adjusting
the valves on the Chetak or Legend. As I write this, I hear a voice
in my head telling me that "no good deed goes unpunished"

Valve clearance adjustments are made with the engine at room

Remove the spark plug.

Remove the screws holding the plastic fan shroud and remove the fan
shroud. This exposes the flywheel and you will more easily be able to
remove and replace the valve adjust covers. The 2003 Legend and
Chetaks have a wrench in the tool kit for removing the valve adjust
covers, if you don't have the tool, a large adjustable will do, but
please! no pipe wrenches, pliers or other barbarian tools.

Put your finger over the spark plug hole and rotate the flywheel
clockwise. When you feel pressure building in the cylinder you will
know that the piston is coming up to it's compression stroke. This is
important because there are TWO Top Dead Centers. One is TDC on the
compression stroke and one is TDC on the exhaust stroke. If you pick
the wrong TDC, disaster will result. On the compression TDC both
valves are off of the cam. On the exhaust TDC, the exhaust valve is
being lifted by the cam.
Now you can use a soft probe to determine TDC (like a plastic straw)
or, since you have the shroud off, you can now see the lines on the
flywheel through a rectangular slot in the engine housing. There are
3 lines in the flywheel. The leftmost line is TDC the two to the
right indicate the two stages of spark advance used by the TRICS
system. This is more than you need to know. As long as you are
somewhere around TDC on the compression stroke, you will be able to
accurately adjust the valves. Even if the piston is half way up on
the compression stroke or halfway down on the power stroke, your
valves are still off of the cam and can be adjusted properly.

The first thing you want to do is check to see if your valves actually
need to have the clearance adjusted. The proper clearance between the
rocker arm and top of the valve stem is between .08 to .12mm. If you
have American size feeler gauges then it's .003 to .004". .003" is
about the thickness of 20 lb. bond copy paper. I tell you this, not
to suggest you use paper as a feeler gauge, but to give you an idea of
how fussy this clearance is. If you make the clearance too small, as
the engine heats up the valve will not seat fully causing leakage,
cause low compression and eventually burnt valves. If the clearance
is too much, the smooth engagement and release of the rocker to the
cam is defeated and the clatter you will hear is the rocker arms
trying to destroy themselves and the valve stems.

When checking valve clearance there are two measurements you must make
with the feeler gauges. The .003 must GO, the .004 must NOT GO. If
the .004 fits but is snug with a little drag that's OK, if the .003
fits but is snug, that's OK. The difference between a snug fit and
not going is around .0002" difference. (Take that .003" copy paper,
peel it apart into 3 separate .001" sheets. Now take one of those
sheets and peel it apart into 10 separate sheets, each sheet is now
.0001" thick, take just 2 of those sheets, that's the difference
between slip and snug.)

If the valves require adjustment, use a 9 mm box wrench (never an open
end wrench) and a small adjustable wrench (or better yet Valve
Adjusting Screw Holder P/N 37103153)
Loosen the 9mm nut just enough to be able to turn the adjuster screw
(while feeling a little drag on the adjuster). Hold the 9mm wrench
steady and turn the adjuster screw clockwise to reduce clearance and
counterclockwise to increase clearance. The adjust screw has a very
fine pitch, non the less, a 1/10 of a turn on the adjuster screw could
make the difference between GO and NO GO. Make very small
adjustments, re-tighten the 9mm nut and check the clearance. This
procedure requires a fine touch and patience, it may take several
tries before you get it right. When tighenting the 9mm nut, be sure
to prevent the adjuster screw from turning. Need I remind you that
this is a small nut and requires less torque than larger nuts?
Specifically, torque for this nut should be .9 to 1.0 kgm.

Make sure the "O" rings under the valve covers are in good condition
and seated properly. Since these covers are made of aluminum and have
fine threads, carefully thread it into the cylinder head by hand...
it's easy to cross the threads. Then tighten .5 to .9 kgm

Replace fan shroud. Tighten screws .6 to .8 kgm.

Put some anti-seize compound on the spark plug thread and install.
Tighten 2.5 to 3.0 kgm 

The Modern Bajaj Chetak Rides On The Modern Bajaj Chetak Rides On