Twin carbs to single

Hey guys I'm new to this place and looking for a little help I have a 1977 kz400 and it has twin carbs that ate giving me fits I want to change it to a single carb setup carb or carbs do I have to choose from thanks for the help

I have seen several threads on this topic, and my takeaway is that it is almost always easier to get the stock carbs to work than to get a single carb to function properly. Perhaps if you told us what setup you have and what the problems are, the members here could help you get what you have working.

Most 77 Kz400's came with diaphragm carbs and so far, no one makes replacement diaphragms yet. I was hoping JBM industries would be , but so far not yet.

So the common options are to swap to older piston-slide CV carbs, or dual Mikuni VM carbs or a single Mikuni VM carb. All of them require new carb holders or intake manifold.

There was at least one company, maybe more, making 1-into-2 manifolds, but I don't think they are anymore. You might find a used one for sale somewhere.

The biggest problem with 1-into-2 on the early 400's is that the frame is in between the carbs so the carb has to be mounted off-center, which makes for uneven carburetion between the two cylinders. It can still work, but it's not ideal.

I have tried the dual Mikuni option using Chinese knockoff VM30 carbs. We haven't really started jetting it yet, but were able to get it to run and ride. We used the earlier carb holders, but they don't really grip the carbs perfectly, so we'll have to source new ones of those before doing any in-depth jetting.

The biggest gotcha with dual VM is the choke system and then there is also a throttle cable issue. You'll probably have to get a custom one or make one. We made one out of aftermarket Honda CB200 throttle cable parts.

The most common VM's to use are probably 26 to 30 for both single or dual use.

Here are some photos and details of the Chinese VM 30's. No one recommends using them. I'm not sure I recommend them or not.
www.kzrider.com/forum/11-projects/611489...00-s?start=24#812094