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flooding/petcock issue

  • Thread starter Thread starter kevsgs
  • Start date Start date
I'm just at a loss

I'm just at a loss

I put the carbs back on the bench with the temp tank hooked up, and they immediately started overflowing again. I put in brand new OEM valve seats and needles and O-rings, they should not be overflowing at all. AHHHHHHHH!!!!!! This is ridiculous!
 
prove the vacuum at the hose

prove the vacuum at the hose

Have you proven that there actually is vacuum at that hose thats sposed to open the ,,,,,,,,,,ON,,,,flow thru it. If you have a vac gauge, it would be good to see what the vac level is there. When I mentioned diaphragm, I was thinking the carb diaphragm, and the question was, ,,,,,,if there was a problem with the carb diaphragm, maybe being out of place or leaking, does that affect the vacuum at that vacuum line that opens the petcock.

Regarding the overflow,,this is a longshot,,, is your temp tank,, at a similar height compared to what the reg tank would be if the carbs were on the bike. I am thinking maybe there is excess headspace here, putting the column of fuel higher than it would be under normal circumstance and putting more fuel weight on the needles and seats. The reason I think headspace could be a problem, is that my gk eleven runs less well with only a quarter tank of gas, if I go fill it up, it seems to run better.

I also have to ask, are the new needles and seats, identical to the old ones visually, because if I am reading this correctly, youre suggesting that the new ones overflow quicker and harder than the old ones. The difference could be the headspace thing, or the WRONG parts if I dare say so.
 
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There's a little check valve inside the petcock for the vacuum line. Perhaps it has dried out or has dirt in it making it hard to operate, maybe shoot some WD-40 down inside the tubing and work it free.
It shouldn't take much vacuum to operate it.
 
banditom said:
Have you proven that there actually is vacuum at that hose thats sposed to open the ,,,,,,,,,,ON,,,,flow thru it. If you have a vac gauge, it would be good to see what the vac level is there. When I mentioned diaphragm, I was thinking the carb diaphragm, and the question was, ,,,,,,if there was a problem with the carb diaphragm, maybe being out of place or leaking, does that affect the vacuum at that vacuum line that opens the petcock.

Regarding the overflow,,this is a longshot,,, is your temp tank,, at a similar height compared to what the reg tank would be if the carbs were on the bike. I am thinking maybe there is excess headspace here, putting the column of fuel higher than it would be under normal circumstance and putting more fuel weight on the needles and seats. The reason I think headspace could be a problem, is that my gk eleven runs less well with only a quarter tank of gas, if I go fill it up, it seems to run better.

I also have to ask, are the new needles and seats, identical to the old ones visually, because if I am reading this correctly, youre suggesting that the new ones overflow quicker and harder than the old ones. The difference could be the headspace thing, or the WRONG parts if I dare say so.
Click to expand...
I put the carbs back on the bike after another succesful bench test, and with them hooked into the gas tank while on PRI it still overflowed the carbs. Started up the bike and kept it running while playing with the petcock to keep bowls with gas but avoiding overflowing, and pulled the vacuum line to feel how much vacuum it had. It should have had plenty to open up the fuel line. Then turned off the motor and filled the float bowl with fuel, then ran a clear line from the petcock for the fuel into a can, and hooked up the vacuum line, started the bike to see how much fuel it is pulling and it barely was pulling any, it was just barely tricklin out. Which explains why when its in ON position I'm just burning through the fuel in the bowls then it dies.
 
banditom said:
I also have to ask, are the new needles and seats, identical to the old ones visually, because if I am reading this correctly, youre suggesting that the new ones overflow quicker and harder than the old ones. The difference could be the headspace thing, or the WRONG parts if I dare say so.
Click to expand...
The parts were OEM from suzuki.
 
sedelen said:
There's a little check valve inside the petcock for the vacuum line. Perhaps it has dried out or has dirt in it making it hard to operate, maybe shoot some WD-40 down inside the tubing and work it free.
It shouldn't take much vacuum to operate it.
Click to expand...
Where would the check valve be located? There was a small little hollow tube on one side, would that be it? I think I just have a bad petcock, the amount of vacuum I'm getting should open the fuel up.
 
frustration

frustration

Hi,

What frustration you have to be feeling. So do the new parts in the carbs, look exactly like the old ones. Are the o rings, soft or hard that are in the needle seat area. I am also wondering if there are overflows or vents that could have been hooked up wrongly. I dont know much specific about the 550 carbs at all, but have heard of fuel lines being hooked up wrongly to atmospheric vents elsewhere and flowing all over the place. With the level of attention youre paying though, I doubt that is true.
 
banditom said:
Hi,

What frustration you have to be feeling. So do the new parts in the carbs, look exactly like the old ones. Are the o rings, soft or hard that are in the needle seat area. I am also wondering if there are overflows or vents that could have been hooked up wrongly. I dont know much specific about the 550 carbs at all, but have heard of fuel lines being hooked up wrongly to atmospheric vents elsewhere and flowing all over the place. With the level of attention youre paying though, I doubt that is true.
Click to expand...
Yea a little bit frustrated but something has to work sooner or later. The overflow vents are part of the main body, the gas is just flowing up past the bowls and out, which the fuel should not be. I have heard others on the boards talking about how PRI will overflow the carbs if left on. When its turned to ON position it seems to work correctly. This last week we had it fired up and running without the overflowing with it turned to ON, then it just quit. Well the problem was we stopped getting fuel to the bowls. Last night I raised to float height just a touch and they worked great on the bench test which would be like being on PRI. Took the petcock apart and made sure it was not clogged and diagphram was working, ran a clear line from the petcock to a can, sucked on the diaphram hose to create the vacuum and could get the fuel to flow with enough vacuum. It took a lot though, just a little vacuum and not much fuel. So we put it all back on the bike and were having the problems already mentioned. So while we were messing with things we decided to fill the float bowls so it would run long enough to test the vacuum line. Ran the clear hose from the petcock into a can so we could watch how much fuel was being pulled. Started it up and let it idle, gave it some high revs, and we never got more than a little trickle coming out. We got way more when I sucked with obvious more vacuum than the bike is giving out. But the bike was creating plenty of vacuum, it should have easily engaged the petcock. So at this point all I can think to do is put in a new OEM petcock and go from there. That will be the last part of the system that is not new, well besides the floats but they're working fine. What I need is a couple of clear float bowls so I can visually watch whats happening..lol. There's a million dollar idea right there ;)
 
sort of like these ??

0630003306.jpg


don't ya just wish it was applicable to our bikes....

http://www.ve-uk.com/general-and-universal-parts/clear-float-bowl/0/malossi/

or these

Schwimmerkammer-transparent-PWK-blau.png


http://www.lambretta-teile.de/Float-bowl-clear-PWK-blue
 
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for what its worth, hahaha

for what its worth, hahaha

Yammi has a tool that allows a threaded tube apparatus that screws into the float boal bottom. Then you take the tube, curl it around and visually see what level the fuel is at in each bowl. You cant buy it anymore, but I have made one, and can tell you how I did it if you want to try. An auto parts store here, has access to stores across the country, its called,,,, auto value,,, thats the chain, similar to napa. I ordered five ten mm threaded grease zerks, and drilled the guts out of one of them and put on a tube, so that you could curl the tube around and see what the fuel height was in the bowl. I have no idea what happened to my tool, but they prolly have zerks in the thread you need, I am almost sure that its a ten x one mm, just take one of the bowl drains and take it to the store. I will say, that I dont consider this tool I am talking about to be real valuable, but I just made it to do it. If you want to do this, and you cant find the zerks locally, I will do a quick once over on my spare parts and see if I can find the tool or the zerks and mail it to you if you want. You sound as if you are ready to try something like that. good luck man, I have definitely been there .
 
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kevsgs said:
Where would the check valve be located? There was a small little hollow tube on one side, would that be it? I think I just have a bad petcock, the amount of vacuum I'm getting should open the fuel up.
Click to expand...

This is a petcock rebuild tutorial, I realize that it's probably not the same petcock you have, but it pretty much functions the same, you just don't have the reserve position. That check valve is referred to as a "blow back" valve in here, it's internal to the petcock on the inside of the vacuum nipple.

http://members.dslextreme.com/users/storagecliff1/images/suzuki_petcock_rebuild.pdf
 
Well I have went through the petcock and its working properly, with new o-rings, new valve seats and needles the carbs are still overflowing even when bench testing. I am at a total loss. Even spoke with a few bike mechanics and even they say everything I've done should have stopped the overflowing. I'm hoping someone can possibly have an idea as to what I can try to do with them?
 
Before it failed and started leaking down vac line, my 30 year old petcock took little vacuum to flow fuel in "ON" or "RES"-you should not have to suck hard. Yours is behaving erratically- sure, you can open it up again and give it your blessing, but why not just replace it for $50 and move on to solving the fuel bowl overflow problem rather than fighting two problems at once?
 
Actually when I went through the petcock I did get a little debris out of it that was causing the slow flow and now works perfect. It doesnt take much vaccum at all to make it work now. My problem is the overflowing bowls. Which seem just unable to fix. I'm wondering if there is a problem with the carb bodies themselves, but nothing is apparent. So I am down to just the one problem. Any ideas on that one?
 
Overflowing bowls are usually one of two things (or both):
Float level set too high
Needle and seat dirty or worn.
The needle and seat are only $8 each if that is the issue.
 
I just put in brand new seats and needles, had them out yesterday while working on it and checked them out with a magnifying glass in case there was a microscopic problem, they are perfect. I've played with the float level and that doesnt change anything. But I guess I can go try to play with float level again, I've already got it set passed what the service manual calls for, 0.81", I have them at 0.90" and they still overflow.
 
Or should I be going the other way and set them lowere than 0.81"? Seems like that would make them overflow more though.
 
At this point, I would try something a bit more drastic, namely removing a bowl, manually holding the float at a level that would guarantee the needle and seat should be closed, and putting a bit of fuel in the line. If it does not seal then, it is the needle and seat. If it does, I would start over with the float level.
 
Well I have finally figured out the problem. There was two lines going from bowl to bowl, one was the fuel line, and the other was a hose. In none of the diagrams did it show this other hose going anywhere, the diagrams were just sort of cut views since they were basically identical bowls and only showed this hose on one side of the carbs. Well come to find out this was a breather hose. So what was happening was as the fuel would come in and push the air in the bowl up, on both sides, the air had nowhere to go and was creating a pressure downwards keeping the float bowls from being able to rise up and close the needle valve all the way. So it now works fine. After taking the carbs apart at least 50 times playing with it, who knows how many hours trying to figure out this problem, I could have taken a pair of scissors and just cut this tube in half in the beggining and been done with it..lol. Well that was a learning lesson, and I now know a whole lot more about carbs, so I guess it I got something out of it...lol. I do thank everyone for trying to help me out with this.
 
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