TOPIC:

Just trying to figure out what carbs this bike has I've heard they are bs34 carbs but more specifically are they bs34 CV or bs34 ss carbs? Trying to find new diaphragm for them and my micrometer to a dump and broke the other day or I would measure. Been looking for a thread with not much luck. Been trying to sync then tune, put pod on and upd the Jets and pilot move shimmed the needle on washer. Got the bike to run but not well hooked up to a sync tool and just haven't been able to get all the carbs sync the diaphragm didn't have any holes but the edges of all of them are warped or missing bits and pieces where they seal. I can push up the needle plunger and they slowly come back down but seems like they could easily get stuck and I don't feel like they are sealing well so I'm gonna by new diaphragm. Thanks for any help.

All BS34 carbs are CV type.

To my knowledge these are the only diaphragms available. jbmindustries.com/Yamaha650.html

An option to consider:

I guess my carbs a 34ss they were 70mm when I measured anyway I went and bought new diaphragm thanks for the help

You won't have great success getting perfect running with pods on CV carbs.
The CV's like smooth still air which individual pods don't provide.
The unbalanced pulses sends the slides out of sync to each other no matter how accurately you vac balance them .
To make the best of a bad job you need dual pods which attach to each pair.
This goes some way to smoothing out the air flow as the separate pulses dampen out each other to some extent.

Mikuni carb engineers spent months designing air filtration for carbs. They achieved the very best overall performance using the airbox. Individual pods may work fine for specific applications such as racing where the throttles are usually wide open, but unlike folks who ride on the street racers are not particularly concerned about how the engine performs at low or moderate throttle openings. Below is an article written by a Mikuni engineer who is an expert on carbs. Also, there is an article below from Cycle World in which they tried over an extended period to make pods perform as well as the airbox. Please read both and then decide if pods are really what you want to fiddle with. Ed