Instruction manual

ManualsBrandsA.J.S. ManualsAutomotive18S

CARBURETTER ADJUSTMENT

To ascertain if the setting is correct, a rough test Is to warm up the engine and, with the

ignition fully retarded and the air about three-quarters open, gradually open the throttle

to full open, during which the engine should respond without a misfire, but, upon a

sudden opening of the throttle, it should splutter and stop. (The engine should not be

run for more than a few seconds with the ignition fully retarded.)

To check the setting of the pilot jet and its air control, warm up the engine, then, with

the ignition about two-thirds advanced and the air about three-quarters open, the engine

should idle positively and evenly when the throttle is almost closed. If it fails to do so,

adjust the pilot jet air screw (18, Illustration 15) inwards, or outwards, until even firing

is obtained. (The pilot jet air screw is at the base of the mixing chamber and its position

is locked by a nut. See 17 and 18, illustration 15.) This adjustment is not unduly

sensitive, and it should be possible to obtain the correct adjustment in a few seconds.

In the event of the adjustment of the air screw failing to provide the required result it

is possible the pilot jet is obstructed with dirt. The pilot jet is actually a passage drilled

in the sprayer base, or choke, and is very small, so there is always latent danger of this

becoming choked.

Upon removing the float chamber and the large nut at the bottom of the mixing chamber,

the sprayer base can be pushed out of the mixing chamber and the jet can be cleared by

using a strand of fine wire.

Before concluding that incorrect carburation is responsible for heavy petrol consumption,

and before carrying out any of the tests and adjustments described above, it is most

important to make sure the ignition is set correctly. Late ignition usually causes a

great increase in petrol consumption.

TWIST GRIP ADJUSTMENT

A screw is provided in one of the halves of the twist grip body to regulate the spring

tension on the grip rotating sleeve. This screw, which is locked by a nut, must be screwed

into the body to increase the tension.

The most desirable state of adjustment is that when the grip is quite free and easy to

operate but, at the same time, will stay in the position in which it is placed.

The complete twist grip can be moved on the handlebar by slackening the two screws

that clamp together the two halves of the body. The most desirable position is that in

which the throttle cable makes the cleanest and most straight path to the under-side

of the petrol tank.

During assembly, all control inner cables are coated with a graphite lubricant. This lasts

practically indefinitely, but should a new inner wire be fitted this must be similarly

treated during assembly.

AIR FILTER

In locations, such as the United Kingdom, where the roads and atmosphere are

particularly free from dust, it is not considered necessary to have an air filter fitted to

the carburetter, but in countries where the atmosphere contains a very heavy dust

content, an air filter is essential in order to prevent abrasive wear.

The filter we supply as standard for the conditions mentioned above is of the "Oi l

Wetted " type, and this requires periodical servicing.

When servicing the air filter, withdraw the filter element. Thoroughly wash this in

petrol, paraffin on other suitable solvent and allow to dry. Then re-oil, using one of the

light oils (SAE-20), enumerated in the final table on page 15, and allow to drain before

replacing in the filter case. Clean regularly at intervals of 1,000 miles and renew the

element every 10,000 miles.