What does this carb screw control ?

[Malc_R]

Hi

(Hope this posting of Photobucket link works !)

Please could you tell me:-

1) What the large brass arrowed screw near the temp compensator is for ?

2) Typically, is there a standard/start-up position for it - ie screwed fully home ; back a turn etc..?

http://i1278.photobucket.com/albums/y513/malc_r/carbscrew_zps10d25ed9.jpg

Thanks in advance

Malc

[martin]

Good pic. It's a fine tuning air bleed, screw it all the way in, then back off three quarters of a turn. Some say screw it all the way in as it has no effect, but I'm not convinced. Martin.