Bottom End!

[handthrottle]

Hi All
A friend is helping me set up my Raptor 50 engine (Thunder Tiger Pro .46), he flew it but said that 'the bottom end' needs tweaking' next time, any chance of anyone elightening me on 'What' does the 'bottom end' do and the 'tweaking' it needs doing. apparently the engine loses power when leaning out!
As always would appreciate any hellp/advice.
TC

[Made2Fade]

He'll be refering to the low speed needle. The one in the throttle arm barrel.
It affects the throttle from idle to hover. If i remember correct you want it running very rich on that needle then lean the high speed needle out. If you dont it will seem very lean around the hover point.
Lee