Mikun BS34 vs Keihin CV34

I know this has probably been covered a lot over many threads in this forum but my search skills are not yielding much.

I currently have a set of Keihin CV34s on my KZ750 H2. I don't have any major issues with them. Bike seems to run pretty good, to me. It is all stock except for Dynatek coils and copper-core wires I just put on it.

However, I have an opportunity to pick up a set of BS34s. Can someone summarise pros/cons to the two types of carbs? A few questions I have off the start is:

1) Do the BS34s mount the same as the CV34s or will I need to modify something to get them to fit the stock airbox?

2) Is there an inherit performance benefit to either?

3) Are the BS34s easier to work with and/or find parts for? (This whole post was initiated by a post I read stating that the diaphragms for the CVs can be hard to find or very expensive whereas the BS34 do not have this issue.)

If there are other things that you like/hate about these carbs feel free to include that too. I hope this isn't a hated discussion around these parts.

Yes to questions 1&3. A little to question 2. The Keihin were a much cheaper carburetor and were used on the lower performance bikes. You will notice that all the GPz750s had the Mikuni carbs.

I have tried both carbs on my 810 kz -82 and mikunis makes bike feel bit stronger, acceleration is faster IMO. Both carb sets are dyno jetted and pod filtered. Keihins are ok but there is something more on mikunis. I like that mikunis are better.

See, I've heard the opposite about the bs34's. One guy even cracked a joke about having them on his snowblower...

I have the CV34's and JR can attest to this (I think WG also agrees), once set up and clean, make really good power and are smooth. I did get lucky and get a complete parts set for $25 (4 good diaphragms too...cha ching!). After about 15 cleanings, I couldn't be much more satisfied with my 34's. Alas, I did keep everything stock, which helps with having to find parts.

I'd say if the bs's are cheap enough, pick them up. Good insurance policy.

I would take the Mikuni over the Keihin any day of the week and three times on Sunday. I absolutely hate the Keihin carbs. My brother has them on his ZR750 and they are a pain in the ass.

just curious, why are they a pain?

First of all the parts are much harder to find, The diaphragms are nowhere as durable as the Mikuni and the rebuild kits that are available do not give you all the parts required for the complete rebuild. They also always seam to have a flat spot when using them with pod filters, no matter what you do to them.

Hey otakar you know those little rubber boot things on the choke shaft?
Do you need them or can I rebuild the carbs without them?

I would replace them. If you get air threw the plungers you can have idle problems.

I use dyno jets and pods with cv34 carbs, and there is no flat spots. I have dyno sheet and A/F ratio is good. Little bit rich between 4000-6000 rpm, but not much.

otakar wrote: I would replace them. If you get air threw the plungers you can have idle problems.

Were can you get them?
Other than Z1 (sorry Jeff) cause they cost $11.34 a piece.
And I need all four.

I have a new set of the Mikunis coming. Can't wait to try them. I am going to install my 1075 engine.

The Mikunis are great,trouble free carbs. I have been running mine for several years.They look good and I get great gas mileage.

I finally replaced the vacumn petcock with the new one that Jeff has. Roy