If it is intermittent, another possibility is that your throttle cable may be routed wrong and is hanging up a bit. Does it idle fine when sitting in neutral or rev on it's own if you turn the handlebars one way or the other?
Well, I think that the P8 needle jet is a little excessive. Probably a P6 would be the most needle jet needed.You have some clutch drag, which is not unusual, and that is what is pulling the rpms down when you put it in gear.However, the typical high idle issue at stoplights usually comes from setting the carb when the bike is not fully warmed up. Try setting the idle speed at full warm engine. Depending on how the mixture is set, sometimes the idle goes high, or sometimes it stalls out. I have seen both symptoms. After doing that, then, it might be a little stubborn when cold, but that's a good thing because it makes you wait until it is warmed up some before you ride off hard.
Ace, you are right. Mike_D had also suggested me to set idle when the engine is warm. I'll try that again.Regarding jets, we started with P6 but it was popping a lot. We tried P4 and popping from the exahust was even more. P8 has no too negligible. I may try P6 again after this idling issues is fixed and see how it responds?Thanks
Turning the handlebars has no effect on it. RPM rises sharply only when it is sitting in neutral gear. The moment I engage the gear, rpm comes down to normal