1、idling stop
If Engine starts well from low speed to high speed, but shut down or firstly act well then shut down after releasing accelerator pedal. The phenomenon calls the malfunction of idling stop.
The 1st solution is idle tune-up. If the rune-up is workable, the reason is misalignment of idle screw.
If unworkable, it needs open a little throttle valve and maintain running of engine, use a cotton yarn or a lip of paper to check air leaking near the pads of carburetor, intake-tube;
If no leaking, it needs to take off idle metering jet to check, and blow-off through idle fuel access, then get back and check. If the phenomenon gets ok, it dues to the jam of idle metering jet and idle fuel access.
If the carburetor has cut off value, it needs check the active of its electromagnetic coil.
If electromagnetic coil is not workable leading to the jam of idle metering jet, then it needs repair the cut off valve.

2、Idling instability
When idling instability, exhaust pipe sounds unusual” hum, hum”.
The engine stability under a certain revolving speed, listen to somewhere there is air leakage. It may be difficult to know, you can paint a little engine oil in the middle and lower of pads of carburetor. Where oil is breathed in is leakage place, you can fasten screw or add and subtract pads to solve.
Then put in throttle valve screw to up the revolving speed of engine. And then loosen a little to overview the revolving speed that is stably or not. And loosen more to check the fan uniform rotation and can see outline of fan blade(400r／min).

If all is unworkable, need to check oil level through peep hole of carburetor.,
if oil level is too low, then need to adjust. If the check it ok, need to check the pipe of wiper and intake and exhaust manifold whether are broken or air leakage. To disassemble carburetor and blow-off through idle metering jet and Idling air jet. Get back, if workable, it dues to jam of Idling jets.
If above check is not god for idling, the malfunction may be engine, usually it dues to too big space of intake valve stem and conduit. Or, your engine needs to overhaul, open cylinder cap to repair it.

3、Idling speed too high
Idling speed is higher than normal, and cannot be gotten slow by tune-up, the phenomenon calls the malfunction of idle speed too high.
Stop the car in flat road, push choke button Hand acceleration pull button at bottom to check. Close the Throttle Valve by Throttle rocker arm, if the idling speed becomes normal, the reason is the spring of carburetor throttle control too soft. If unworkable, need to check throttle spindle whether loose or tightly closed. If throttle valve is ok, it needs tune-up by idling tune-up screw.