My fiddy used to run like a champ...now that I put the 88cc in with the 20mm Carb it won't start for sh*t when it is cold..even with the choke on..

Anybody else have this problem..or any ideas...

 

only if it is really cold 30* degrees or lower
just warm the head with a torch thats what i do

 

Try going up 1 or even 2 sizes on the main jet. My 88 with the 20mm started running shitty when it got real cold. I went up one jet size and its mint. Also make sure the choke is working properly (opening and closing) Just because the lever moves doesn't mean it works

Colder air is more dense and holds more oxygen so you need to compensate for it by giving the bike more fuel. There is a mixture screw on the carb as well that you can fiddle with to tailor the air/fuel mixture. Try going clockwise in 1/8 inch turns at a time.

 

I would consider going up on the pilot jet. get it running first and see how it is before you change any jets, then try the mixture screw. then raise needle if necessary. Although it is true that cold air is more dense, the main jet affects 1/2 to full throttle. It will not help cold or hot starting.