Overflow routing on 81 CSr 650

I have an 1981 CSR 650 that is bone stock. When I got the bike the previous owner had the overflow lines routed strangly. Bowls 1 and 3 were connected. Bowls 2 and 4 were connected. Bowl 2 has an extra spigot out of the bottom that has a line on it that is routed to the bottom of the bike. I am trying to decide if this routing is correct.

When you look at the inside of the bowls... there is a hole a the bottome of the bowl that drains into the overflow line. The overflow tube also flows into the overflow line. If each bowl is routed with its own overflow line then the carbs will pour gas onto the ground becasue the line is open to the bottom of the bowl.

Connecting the bowls in the manner of the former owner causes the gas in the bowls of carbs 1 and 3 to be the same and 2 and 4 to be the same. The bowls equalize because the overflow lines are routed to each other. I guess if the gas gets too high it will somehose casue the gas in bowl 2 to flow out of the second spigot which is open to the ground.

Even if the owner had the lines routed wrong.... how should they be routed? They can't be open to the ground becasue the bowls will just empty.

del

I really dont know anything about the mikuni carbs but wonder from your description if the drain screws are missing and the previous owner just linked the carb overflow lines together rather than replace them. I did exactly that once as a temporary repair

If you go to www.kawasaki.com click on owner information, select parts diagrams etc etc you may be able to get a good parts diagram for your carbs...that is if you dont already have a manual.

Regarding routing of overflow and vent lines like JKZHI says or check out wired georges website. I think he may have photos on there

Are there suppossed to be drain screws on the inside of the bowls? My external drain screws are there but I wasn't aware of internal drain screws. I can't remember if I saw threads in the openings in the bottiom of the bowls.

There is a brass overflow fitting on each carb bowl. That is what the hose attaches to. The brass fitting extends up into the bowl and goes into a tube that sits above the normal gas line in the bowl. When the bowl overflow, the tube carries the overflow down the tube and out the brass fitting and hose. The hose should be routed away from the engine (engine hot / gas burns easily). There are also 6mm steel slotted drain screws (some bikes have brass screws). These are used to drain the bowls as the name implies.

I follow so far but here is my issue. There is a hole... about 2 mm in the bottom of the bowl from the inside that connects the bowl to the brass spigot that comes out the bottom. This hole does not go completly through the bottom of the bowl. It connects the bowl inside to the brass spigot. This is carbs 1,3 and 4. so lets say that I have the open bowl in my hand and off the carb. If I put say 1 inch of gas in the bowl... the gas immediaetly drains out of the overflow hose becasue it flows from the bowl to the brass spigot. So I get gas out of the overflow line as soon as gas reaches the bowl. But it looks like this isn't normal. I will look today and see if this hole is tapped. I can't imagine why someone would have drilled these holes?

Perhaps you could post a picture? I can't for the life of me figure out what you refer to. Will try to take a pic of a VM24 accelerator pump #2 float bowl.

I'll try and geta pic tonight. If you look inside the bowl on the very bottom on both sides of the overflow tube there is a depression in the metal. There is one depression on each side about 1/4" in size. I guess this is a side product of tehe casting process On my carbs I have about a 3/6" hole drilled (no threads) in the depression that is on same side of the carb bowl as the overflow brass spigot. This drilled hole connects the inside of the bowl to the chanber that connecst the overflow tube to the overflow brass spigot. So when gas is in the bowl it flows right into that chamber and out the spigot.

I am guessing someone did his as a performance mod? Or for some other odd reason. Also.... the air box says kz750e. Could this mod be required becasue of the kz750 airbox?

del

JMK... if the 81 has VM24 carbs, none of the KZ700/750 airboxes will work as they all had 34mm CV carbs; either CV34 or BS34.