Withdrawal
Remove air filter (see section «Removal and installation of the air filter»).
Disconnect connector -2- for throttle valve potentiometer. having previously folded back the retaining clip -3-.
Loosen screw -4- from retaining bracket and remove throttle valve potentiometer -1-.
Examination
Remove and check clutch -4-; if required, replace.
Check the ease of movement and the full angle of movement of about 90°of the driver -2-. Check return spring force.
Check the total resistance by connecting an ohmmeter to terminals 6 and 7.
Check the resistance of the potentiometer slider by connecting an ohmmeter to terminals 5 and 6.
If the resistance values deviate from the specified values, replace the throttle control potentiometer. Refer to the carburetor basic technical data table for the specified values.
Installation
Insert the throttle valve potentiometer with mounting bracket so that the slider of the throttle valve shaft engages in the guide slots -3- of the coupling -4-. At the same time, the protrusion -1- on the mounting bracket must enter the locking slot on the potentiometer and on the carburettor body.
Screw on throttle valve potentiometer with retaining bracket.
Install air filter (see section «Removal and installation of the air filter»).
Checking the temperature valve
Start a cold engine and leave it to idle.
Detach vacuum hose -1- from straight connector on temperature valve and check vacuum at hose end. To do this, close the end of the hose with your finger. If the finger is a little «sucked in», there is a vacuum. Otherwise, check the tightness of the hose, as well as the permeability of the hole in the carburetor.
Reconnect vacuum hose -1- and disconnect vacuum hose -2- from oblique connection -2- of temperature valve.
Check for vacuum at the oblique fitting. As long as the coolant temperature is below about 45°C, the valve must be closed. That is, the oblique fitting should not have a vacuum.
Attention: The throttle opening in the valve allows a small passage of air even when the valve is closed.
When the coolant temperature rises above 61°C, the temperature valve should open. There should be a vacuum on the oblique fitting.
Otherwise, the temperature valve must be replaced.
Attention: The temperature valve can also be checked in the removed state. In this case, warm up the valve in a water bath.