Mikuni BS34 Slide Changes

What is the reason for the changes in the slides on Mikuni BS34 carbs? Specifically the flat bottom slides versus the slides with the arch or cathedral bottoms on them? I know the arched bottoms appear on the GPz series which makes me think they are more performance oriented than the flat bottom slides. Anyone know why the two types were made and how they perform differently?

Zero? No knowledge or just apathy?

Are both sets from Kawasaki's? The set on the right looks same as used on Suzuki GS bikes. Regarding the slides, no clue. I don't think it matters tons but I suspect the KZ carbs may have some slight enhancements seeing as how they came out a year or so later than the GS version carbs.

Also true of the aftermarket VM29 carbs. Ones for Suzuki used a 2.0mm cutaway, for Kawasaki and Honda, a 1.5mm cutaway was used.

Thanks for the input guys. Both came off of Kawasakis. The arched sliders are the style that come on the GPz's which suggests to me they are more performance oriented. This particular set with the arched sliders is NOT off a GPz. Those come with stamped steel caps on the top with #1 and #4 in a black wrinkle coat paint and painted carb bodies. This set has the cast aluminum caps. Otherwise they are identical to the GPz carbs. IIRC one of these sets came with the 83 KZ1100 and the other came with KZ1000 CSR. Both of them came to me used, so no guarantee that I received them with the original carbs although both bikes were otherwise box stock when I received them.

I didn't know the 2.0 and 1.5 numbers referred to the size in millimeters? I thought it was lika the size on a T-shirt, Large, Medium and Small? Please enlighten me, if I'm wrong! Someone?

Yes, millimeters. That refers to the height of the cutaway (arch) on the slides.