ID of carbs

[AMR-XS400]

Hi guys, i have 6 sets of Carbs that came with my basket case xs400. a number of them have white on them saying XS400. I have noticed that they all look very similar bar slight differences . The big difference is the air intake port. can anyone id these carbs?

 

[gentlemanjim]

Pic 1 is Mikuni BS38, 2-BS34, 3-BS38,4-BS38, 5-BS38, 6-BS38

Best way to tell them apart is the BS34 have a stamped steel chrome diaphragm cover and the mixture scew is vertical. BS38 have acast aluminum diaphragm cover, the mixture screw is horizontal and the main jet is accessed externally from the bottom of the float bowl.

They are both good carburetors. I personally prefer the BS34's

 

[xschris]

The xs360's used a BS34 that looks like a BS38 that was on the xs650 pre 80 I think that is what he has. The 77-79 xs400 BS34's have a molded cover the 80-82 have the stamped tin ones. The carbs that are linked are the 77-79 34's

 

[AMR-XS400]

for all the people here who have gone single carb conversion, should i go with a BS34 or a BS38

 

[gentlemanjim]

for all the people here who have gone single carb conversion, should i go with a BS34 or a BS38

You might want to post this question on the XS650.com site.

 

[sprocket]

For a single carb I've heard nothing bad about using one of the stock carbs.
I've been building these for a few years for both XS400 and 650.

You will find that the #1 cylinder is slightly lean and there's really nothing you can do to fix that with a single carb. It has to do with the crank phasing in the 400, 180* instead of 360* like the 650.
Personally I would go with the 38 for this application and jet accordingly.
Jet up until cylinder 2 is slightly rich and 1 is closer to spot-on. Rather run rich than burn pistons.
I'm working on a new design manifold that may help this issue somewhat.
I'll be working on that a bit today after I finish one of my manifolds for Deus on this site.

Info and pics of the current manifolds I build is here:
http://www.xs400.com/forum/showthread.php?p=89976#post89976