i'm considering converting my S5 NA 6 port to ma 51mm DCOE Weber Setup.
Has anyone had any experience with Winter 20Degree Start up issues or Tuning issues at 8000rpm? because of the main and air jets and emulsion's at High RPMs effecting street driving? any input would be good to hear

 

can't comment on the 20 degree starting, but if you're prepared to spend a lot of time on the carb you can get the mixtures very close to ideal all the way thru the rpm band.

with the weber it is a little tricky to get the transition between the idle and main circuit to work, and this seems to be in that 2500-3000rpm range, but once you do, it drives really well. there are a few ways to do it too, you can either get the idle circuit to deliver a little more fuel, or get the main circuit to "turn on" sooner.

EFI does have an advantage, if you want 13:1 idle, 14.5 cruise and 13:1 WOT EFI is no problem, with the carb sometimes you have to compromise a little.

with mine, the only trick i really used was that i kept a little journal, and i started with idle and changed each part (jet, or whatever) one at a time and recorded the changes. once you have a handle on what part does what when, its pretty simple.

on the cold starts, the P port starts right up @50F with no choke, so i don't see why not, but at 20F i haven't tried...

 

I have a side draft S5 13b streetport that starts no problem in 0 degree weather, I use it for ice racing.

Just make sure your carb has a choke, otherwise it would be difficult to start.

 

I keep a plastic grocery bag in the REPU as my choke. Wrap it around the filter and cold starts go much better. In AZ the last 10 years so not so much of an issue any more, but thats what I did in colorado. i wouldn't recommend doing this if you don't run an air filter.