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Author Topic: leaking carb, badly working petcock  (Read 1753 times)

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marp68

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leaking carb, badly working petcock
« on: April 04, 2008, 10:46:20 AM »

Hi

Took the old girl out today. What a feeling riding her again after a long winter. :)

But, it seems to be a problem with the vacuum petcock. I started the bike with the petcock set to PRI just to be sure to get gas, then switched to ON to use the vacuum instead. This worked before the winter. Now, after a while, the engine started to go poor and finally stopped due to no gas. I then switched back to PRI and the bike started. When I then switched to ON the same thing happened, the engine died. The same thing happens if I switch to RES. This make sense, since I imagine that the ON and RES both work with vaccum, right? Anyway it seems that I can run the bike with the petcock set to PRI.

I've also noticed that one of the carb is leaking. It seems that the gas is coming from the small plastic T-tube that connects the two centre carbs with the rubber gas tube from the petcock. Could it be the o-ring or gasket that ought to be where the plastic tube enter the carb? Or is it the carb itself that is leaking from some other place close to this tube? There should not be any leak, even though I'm running the engine on PRI, right?

Any idea of how to get the vacuum petcock working correctly and fix the leaking carb? Are the problems connected with eachother or are they two seperate problems?

I also intend to post some nice images of the bike. It has been well cleaned up during the winter.

/Martin

« Last Edit: April 04, 2008, 10:50:40 AM by marp68 »
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herk

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Re: leaking carb, badly working petcock
« Reply #1 on: April 04, 2008, 11:40:56 AM »

Is the carb-to-petcock vacuum tubing connected?

Fuel should not be leaking.

My bike is the 81 650CSR & has a metal fuel delivery tee between the middle carbs.
I had a leak there that was solved by kinda moving the tee around to reseat the o-rings.  JMK.
 
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Greg

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Re: leaking carb, badly working petcock
« Reply #2 on: April 04, 2008, 10:58:26 PM »

That fuel T is actually rubber-coated aluminum and sometimes the rubber coating just gets old and leaks. Follow herk's advice and move it around a little. If that doesn't work they are available from Kawasaki. If I remember correctly, they cost about $12 when I had to replace them on my KZ1000.
If your vacuum lines are connected, you may need to take your petcock apart and clean it. It is possible that the diaphram is leaking. It is also possible that it will tear when you take it apart, so be prepared to buy a rebuild kit. You can also just run it on prime, just remember to put it back on "on" when you kill the engine. Also know that in prime position it picks up fuel from the reserve port, so when you are out of gas, you are out of gas!
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marp68

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Re: leaking carb, badly working petcock
« Reply #3 on: April 05, 2008, 05:30:34 AM »

Hi

Yes the carb-to-petcock vacuum tubing is connected.
It seemed that it leaked from the fuel T between the middle carbs, so I will try moving it around. The problem may have appeared when I jerked around to take off the extra gas filter mounted between the rubber tube that goes down to the T and the rubber tube to the petcock. I had to jerk rather hard to get it off.

If moving the tee around to reseat the o-rings doesn't work, is it possible to change to new o-rings without removing the carb bridge and taking the middle carbs off?

I also thinking that maybe something in one of the middle carbs had got stuck by old gas in the system. I emptied the tank and run the engine out of gas before the winter.

Regarding the petcock I may take it apart and clean it. You're mentioning that I could run on PRI, as long as I don't forget to put it to ON when stopping the engine. One strange thing is that when I was out with the bike and had it on PRI, the engine died as well. I still had gas. So I thought it was just the reserve left. Since the vacuum problem also appear wit the petcock set to RES, I added som more gas an, set it to PRI and, guess what, it started again. Thinking about it, you're right, having it set to PRI, it should be possible to run out of gas since it also includes the reserve. STRANGE! I will have to investigate this.

I intend to add a carb system cleaner to the gas to resolve any bad old gas leftovers. This would perhaps clean the petcock as well. What do you think?

Beside the problems, it felt so niiiiice riding the bike again. Nothing like the first ride in the spring, right?

/Martin
« Last Edit: April 05, 2008, 05:33:31 AM by marp68 »
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rstnick

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Re: leaking carb, badly working petcock
« Reply #4 on: April 05, 2008, 12:56:35 PM »

Adding a carb cleaner that's designed to be mixed with the gas and run through couldn't hurt.

I regularly use Sea Foam added to the gas, which cleans as you ride.  :)
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Rob

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'77 C1 project - newest
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marp68

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Re: leaking carb, badly working petcock
« Reply #5 on: April 05, 2008, 01:17:09 PM »

I looked it up, seems like a good product to use. What I will use is pretty much the same.

M
« Last Edit: April 05, 2008, 01:22:02 PM by marp68 »
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Greg

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Re: leaking carb, badly working petcock
« Reply #6 on: April 05, 2008, 02:27:58 PM »

If moving the T around doesn't work you will have to take them apart. there is no other way to get the T out. Also, it doesn't have actual o-rings on it. The seals are molded to the T, so you will need to replace it. You could try putting o-rings over it, but it would be a gamble.
You might want to check for rust in your tank, too. Emptying a tank for storage is generally a bad idea, because it allows rust to form.
I hope you get it going soon. I hate it when a bike just sits there.
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There is a fine line between a hobby and a mental illness.
74 Z1
75 CB750 chopper
77 KZ650B1
77 GL1000
79 GL1000
82 KZ650H2
01 ZRX1200

Link4

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Re: leaking carb, badly working petcock
« Reply #7 on: April 08, 2008, 11:15:14 AM »

My 750 pulled that same thing on me this past month.  After many hours of worry it turned out to be a stuck float in the #2 bowl.  The excess fuel clogged the brass overflow tube in the bowl and gas backed out through the "T" all over the case.  I cleaned and soaked it, then replaced the bowl and gasket for $15. That seems to have worked(for now).  Hope this helps.
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'83 xs650 project
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marp68

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Re: leaking carb, badly working petcock
« Reply #8 on: April 09, 2008, 10:36:04 AM »

Seems like a good point. Could be because the bike has not been started since last season.

Since the winter have returned here in Sweden, I can't take the bike out and test it. Have to wait until the wether get better. I will then try what you all suggest.

M
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marp68

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Re: leaking carb, badly working petcock
« Reply #9 on: April 11, 2008, 08:52:05 AM »

Jippie!!!  :dance: Snow is gone!

I went for a ride today, and guess what, no leak and after a while even the petcock started working correctly. I'm happy.  #-o :dance: 8) Tomorrow is going to be nice as well, so I intend to go for a longer day ride.

Thanks for all advices!

It seems though that it starts easier, when setting the petcock to PRI before starting it.

I tested to adjust the air screws. On #3 and #4 I noticed small changes when adjusting the srews. When I turned one of them completely in, the rpm dropped and the bike died eventually. But when doing the same to #1 and # 2, nothing happened.

Couldn't this indicate that I have an air leak around these two?

/Martin
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mariozappa

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Re: leaking carb, badly working petcock
« Reply #10 on: April 11, 2008, 09:20:59 AM »

Quote
Couldn't this indicate that I have an air leak around these two?

Perhaps the passages for those air screws are clogged.
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1977 KZ650 C1
The 77/82 KZ750 conversion
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