TOPIC:

undefined So, I just finished going through the carbs on my (new to me) bike. They weren't real dirty, and now the bike runs pretty good.  I noticed two things. 
1- the mixture.screws for both carbs were still sealed with the Welch plugs ( I left them as they are)
2- the bowl drain screws, and jets underneath them are physically two different sizes.  The diaphragms for each are the same diameter. But the bevel on the bevel on the slides
are different too.
​​​​​
Is this normal?
I ordered rebuild kits before cleaning, but now fear that one can't be totally rebuilt when the time comes. 
​​​​​

If the plugs are still there then I would guess that’s how those carbs came from the factory. Do you have pics? Its possible someone mismatched parts from a different BS38 setup. Many Yamahas of the era use the same carb bodies but had different setups.

The 1980 carbs are one year only carbs. The pilot screw and carb body  is unique to them, so if you drill out the plugs do not discard the pilot screws as they will be very difficult to replace. If you have a 40 pilot jet i would recommend going up to at least 45 or 50. these were way too lean from the factory.

 There's no Chance of mixing the Drain plugs, main or needle jets between the two. they are different sized threads. One looked "newer" than the other.  
   I'll post some pictures the next time I pull them off the bike.