Low end troubles

[takadi]

So I'm having some troubles on the low end. 150 cc chinese bike. Starts fine, idles horribly. Struggles to idle and has spurts of high idle here and there. When I open the throttle the scooter stalls and shuts off. However, when I leave it on for a while and warm it up, the idle starts to pick up and then it idles beautifully, almost too strongly. The problem at the low end still remains though. It has a delay - open up the throttle slightly and nothing happens for half a second, then the rpms pick up. Getting past the low RPMs on wider open throttles everything is perfect.

[Ebuddy]

Do you have an auto-enricher (auto-choke) on the carb? I've seen this problem several times with these devices. I know some folks have a way of disabling them but they're cheap to buy and easy to replace so I've just taken to replacing them every once and a while.

[CarefulRider]

I don't know how many miles on the engine, but I would thoroughly clean the carburetor.

If that did not resolve the condition, I would then check & adjust the valves, if needed.

[kz1000st]

I would check the intake manifold. I had one crack on me and it caused hard starting, surging and the idle speed to drop off. The valves should be checked first, as he said.