Hi guys. I'm newbie here and have some problem tuning my buggy engine.I know some basic stuff (high needle - clockwise will lean and vice versa.....idle needle- clockwise will high idling and vice versa) but my current problem is:

1) What is the function of low needle?

2) My engine is one gallon old and idling fine (it was broke in by LHS). However, when I give some throttle...my buggy runs smoothly and when I give full throttle for the first time...it runs nicely..BUT when I give another full throttle....the engine sounds like going to die/stall and when I continue giving full throttle..it will die/stall. Whats should I do?

Hope to get some help here.Thanks

P/s: Anyone knows any link/website that teaches how to troubleshooting/tuning nitro engine comprehensively???..