Petcock question 1983 kz750

I have a 83' KZ 750F and my gas line splits into two lines. The one attaches to the nipple on carb 2. Where does the other go? Also, there is no other tube coming from the petcock on this bike (wheres the vacuum?)

chenner32 wrote: I have a 83' KZ 750F and my gas line splits into two lines. The one attaches to the nipple on carb 2. Where does the other go? Also, there is no other tube coming from the petcock on this bike (wheres the vacuum?)

Perhaps the vacuum petcock has been replaced with a non-vacuum (i,e,, manual) style petcock.

Would double-check carb connections.



Good Fortune!

The carbs have 4 nipples but only the three were connected leaving the middle right one empty. The guy started the bike (previous to when I bought it) just with the second split hanging. I have every reason to believe this is wrong.

I haven't put gas in the bike. I believe its going to come out of both hoses.

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The petcock I have is ON - Res - Pri

I stupidly just assumed there was only one tube: I put gas in the tank and adjusted to the Pri position because I cleaned the carbs and it leaked gas all over from a side of the petcock from some hole. The gas line that bificates did not leak. I then changed positions to the ON position and the hole stopped leaking but something still was leaking (not nearly as bad) and only when I turned it over. I'll have to relook at some diagrams.

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I was wildly wrong on the issue. I found the main gas line. I connected it to the petcock. The line that bifricates is the vacuum hose (now to my understanding). The left branch goes into the carb #2 and the right branch was left hanging. The nipples on Carbs #1 and # 4 converge and connect up to the engine ( or something close, I took a fast glance).

I installed everything back together and put the petcock on PRI for a few moments and then I changed it to ON. However, the bike wouldn't start and now has a problem receiving gas (or could be flooded (unlikely cause the overflows are not leaking), The spark plugs are new, and the starter was just replaced. The nipple on carb #3 and the second bifrication from the vacuum hose from the petcock are NOT blocked. Could this cause this problems?

Thanks for the help.

If still suffering with the air injection paraphernalia, just remove it.
Then connect the valve cover inlets to each other.
And cover/plug the resulting air box hole.

Now, cap all unused vac nipples.

Good Fortune!

I'm going to plug them tomorrow and see how that works. The bike should run on PRI regardless and it was running before I put the new starter in.

Where it is written on blue about dual fuel line tees, what if they have caps on them? Am I supposed to tie those tees into the main fuel line going to the petcock .The vents on all the carbs where capped off except for the right middle carb which it had a hose going to the petcock. Is it OK if I ran a vent hose to connect the 1and 4 carb vents and a then did the same for 2 and 3 but they connect to the petcock ?

Cfoux85’

There are three types of open tubes on the carbs. I will start with the ones near the top and work down.

1. Vacuum ports. These are connected internally to the throat of the carburetors. There is one on each carb. One of them will be connected by a hose to the fuel valve (petcock), if it is a vacuum operated valve. The others will be individually capped. The four of them are also used to synchronize the carburetors after a rebuild or at tuneup time.

2. Vents. There is usually one per carb. These are internally connected to the fuel bowls. Their purpose is to is to insure constant air pressure in each bowl by allowing air in and out of the bowl. There should be a hose connected to each one. The hose usually goes toward the battery box, then over a frame rail and down toward the ground in front of the swingarm pivot. These hoses must not be capped or blocked in any way.


3. Fuel inlets (fuel T). These are usually right above the fuel bowls and are larger diameter than the others. On a four cylinder bike, there will be either one or two of these, depending on the model. If there is one, it will be between the middle two carburetors (numbers two and three), and there will be a solid tube between the outer pairs of carbs. The fuel line is connected to the middle tube (T).
On models with two fuel inlets, there is a solid tube between carbs two and three. There is a fuel T between 1 & 2, and another between 3 & 4. A fuel line from the petcock goes to each inlet.