No cold start?

I'm finishing converting my '76 kz900 to BS34 carbs, I'm running 37.5 pilots and 127.5 mains, stock for the police bike they came off of, using the stock airbox, with the holes enlarged for the bigger boots. The air adjust screws are about 2-2.5 turns out. The bike runs great once warmed up, idles fine and pulls great all the way up. Only problem is it absolutely refuses to start cold without ether. It will try to fire on 1 cylinder, but never really makes it, and choking it at all makes it worse. When warm it will start fine, and it doesn't really balk at any rpm. Also have good spark (dyna s) and new plugs.

Any thoughts?

Take off the bowls. Put a straw on a can of carb cleaner and put the straw into the hole in the bowl bottom where gas is drawn into the enrichener well in the edge of the bowl. Put on some safety glasses!!! Blow carb cleaner into the hole. If it doesn't come out the enrichener well on the edge of the bowl, poke into the MIDDLE of the well... there is a small hole and under the hole is a check valve. Sounds like the enrichener circuits are not drawing gas and this is normally where the gas flow is stopped. The check valves get goo-ed up. If the wire doesn't clear the valve, you can also put a propane torch on the outside of the bowl on the well.

If this doesn't do the trick, pull the carbs apart and pull the plungers. There is a HOLE where the needle on the plunger end seats. This hole connects to the tube that sits down in the well on the bowl edge. Squirt carb cleaner into the hole (WEAR EYE PROTECTION). It should come out the brass tube and if it doesn't you will need to clear the brass tube using a wire.

The air passageway on a BS34 seldom clogs as it is under the slide diaphragm and very large.

I've had the carbs apart, and sprayed carb cleaner in every orifice, especially the bowls, and I made sure every passage was clear. The rubber boots on the choke rod are torn, however. Could that cause a vacuum leak? Perhaps that's why the bike never seems to like choke.

I had the same problem and the brass tubes going in the bowls were clogged so it wouldn't pick up gas on choke. You know how to check for vacuum leaks by spraying wd 40 or carb cleaner on the area in question the engine will rev up if it's sucking air..

I'm not trying to insult your intelligence, this is more of an admission of my own stupidity.

I bought a set of BS34s to put on my M2. Before installing it, I took it apart and gave it a thorough cleaning. I also replaced the float valves and gaskets.

The gaskets I bought had several die-cut holes that needed to be "popped out" before installing. I took a look at the mating surface where the gasket was to go, and I looked at the location of the holes on the carb, and compared it with the location of the punch-out holes on the gasket. It looked to me like some of the punch-out holes seemed "optional", as there was no hole directly under the punch out.

So I left a couple of the gasket holes un-punched, assembled and installed the carbs.

I was able to get the engine started, but it was quite difficult to start. Later, I took the carbs apart and discovered that while there was no "hole" under one of the punch-outs, there was a channel that fed the pilot circuit which was blocked because I didn't open up the gasket hole. So I punched out the hole, assembled it, and it fired right up.

Don't know if this applies to your situation, but that was my bonehead move.

And the prize goes to Skyman. Took the bowels off, and sure enough the pilot holes in the gasket were still plugged. Punched them out, and the bike fired right up.

Thanks for the replys.

good call and another hair pulling out problem solved here on kZR.