which carbs should I run

[bumjug]

81 engine inna 76 frame. Which carbs ate better?

I live in a humid swamp for what its worth at sea level

 

[bumjug]

Forgot to post the photo

 

[angus67]

it doesn't really matter. The 38's MIGHT have worn bores for the throttle plates, The 34's MIGHT be a bit finicky to tune. Pick yer poison.
If you go with the 34's, get the Canadian needles and emulsion tubes so that you get adjustable needles for fine tuning.
If you go with the 38's, identify the year that they are so you have a good starting points for your jets/pilots. Many variations of the 38's evolved between 1970, and 1979, every couple years, the appropriate jets changed. Jet the carbs to the carb set, not the motor year.

 

[5twins]

Yes, the choice is up to you. Both sets you have are pretty good choices. The '76-'77 BS38s are a very good set as far as the 38s go. Very nice midrange performance. Your BS34s appear to be an '80 set. Their only short coming is they have oddball sized brass floats. Replacements aren't as easy to find but the later plastic floats can be used instead. The 34s are pretty E.P.A. strangled but can be made right with the appropriate jet changes. They may be the best stock carb choice for these bikes as they were the last and most modern carbs used. Oh, they're also lighter than a set of 38s. This could be beneficial if you plan to run pods and won't have the airbox supporting the rear of the carbs any more.

 

[angus67]

switching to plastic floats is a no-brainer.

 

[hmusket]

Do you have the carb holders for the 34's? Do you plan use the stock airbox and side covers?

 

[bumjug]

Stock airbox for now - gotta get the bike running before I begin to mod it!
Yes I have both sets of carb holders. The ones off the '80 bs38's are pretty cracked though...

 

[bumjug]

decided on the 34's - chasing down elictrical problems as we speak...