Onan 6.5 starting problems

[Trojan bob]

Hey folks..Need some tips.. I have a 1976 tricabin with a 1976 6.5 Onan generator.. Here is what is going on...
Genny starts right up when warm and runs perfect
If it sits for more than about 10 hours, and I start it, the unit starts right up...idles perfect........ but after about 5 seconds it starts to labour..It does this for about 10 seconds and then very gradually over the next 15 seconds or so starts to pick up rpm's and then runs perfect..Its the same every time. I had it tuned up this week, changed the impeller and the oil is good. I can only assume it is a choke issue and possibly I can play with the choke butterfly right after I start it, but I don't really know what I am doing..Im not sure if this labouring is from an improper mixture, not enough fuel, too much fuel or what..
If anyone has any thoughts on what I can do to help remove that initial 15 seconds of slow rpm, rough idling please help me out...thanks

[g36]

does the idle speed up and down likes its hunting?. this could be a govenor issue. spring being weak.
smokstak.com is great wealth of info on generators

http://www.smokstak.com/forum/forumdisplay.php?f=1