Preferred BS carb choice

[Thumper]

In the photo, which carb set would be the better to revamp and use? The top set has E3 markings and the bottom has none.

For docile street use, of all of the stock carb variations, which would be preferred for ease to sync, jet, etc?

I already read through the tech section - is there a good thread here that discusses this further?

Thanks

 

[DogBunny]

This is easy. The top carb is a dual-cable, non-linked carb set.
The bottom set is way better.

 

[Thumper]

Thanks DB. I currently run VM34 rs but want to have a spare set. Are these early 38s (no solex on the cap btw) better than say late 38 or 34? Thanks again

 

[DogBunny]

I might have spoken too soon. Are those plastic over-flow elbows on the bottoms of the bottom set? If so, then they are also dual-cable, un-linked carbs, or they are the wrong float bowls. Need more pics.
The best 38s are 1976-1979. Those are the single-cable, linked ones. I like 38s way better than 34s, but many will disagree, and it kind of depends on your intentions, what kind of bike your building, wild or mild.

 

[gggGary]

Bottom pair look like 74-75 single choke set?
They have a less restrictive venturi, having lost the raised floor of the earlier carbs.
But like DB; the later linked carbs, specially 78-79 are considered the best B38s
IF tractability and ease of tuning are primo I like BS34s
I am interested in the set of those yucky early carbs....

 

[gggGary]

XS1 carb markings

 

[Thumper]

Thank you Db and gG for your expertise, bottoms are twin cable, plastic overflow and single choke. Has H marking near drain plug.
Mild is wild.

 

[5twins]

Honestly, unless I had an older model that took one of these sets that I was restoring, I wouldn't bother using them as spares. I would search out '76 and later linked BS38 sets or a BS34 set (also linked). I have, in fact, done this and am currently running spare '78-'79 BS38 sets on both my bikes. I took these a step further, fitting 5Z1 needles from an XS400 to both, and jetted to match them. I even went so far as to adapt some '77 XS500 BS38s for 650 use. This is the same carb as the '76-'77 650 BS38s, just with all different jetting and different spacing between the two carbs. Adapting them involved changing all the jetting to 650 specs and changing the spacing brackets and butterfly shafts to 650 items to get the spacing right. The carbs came to me on a junk XS500 I picked up several years ago for $25, and I had all the needed parts from a junk set of BS38s, so I figured why not, lol. Along with all the other parts I scrounged off that 500 (brake discs, calipers, instruments, seat/helmet lock, handlebar controls) I really got my moneys worth out of it.

 

[DogBunny]

I agree. I would never waste my time on 70-75 BS38s unless I was doing a 70-75 restoration that had to be 100% correct, and that would be primarily for show, and never seriously ridden.
If you're going to spend the time rebuilding carbs, choose 76-79 BS38s. BS34s are okay if you are leaving the engine and exhaust stock.