1981 KZ550A2 Update

Okay, I think I am leak free. I put the new needle valves and seats in. Bench measured the floats to 18mm. Then did a clear tube test on each carb. #1 and #2 needed adjustment of the float tang. #1 was low about a 1mm and #2 was 3mm high (right at the bowl lip). I think #2 along its weak needle valves was my leaker. Went on 30 mile ride or so and parked. It's kinda cool here so I am gonna wait to vacuum synch again when it warms a bit. Aside from being cold blooded on warm up, she ran great. Thanks to all of you that had suggestions and helped me out. R

No leaks over night. Had a nice 50 mile ride over to St. Paul. No leaks afterward. What is the trick with getting the breather hose on all the way? I could not seat it fully while connecting the airbox. I was gonna unbolt the breather cover, fit the hose and then bolt up the cover. R

Heat it with a hair dryer.
Steve

Gas leak in the garage this morn. :S. I wonder how much of this is plain old fuel expansion. It is still below freezing here at night and warming to 40-50 degrees. Yesterday I rode 30 miles and parked while doing.some business. No leaks. Rode home 30 miles. No leak last night. This morning it leaked. Seems still to be about a bowlful. I will clear tube again with the carbs on the bike to check again. Overfflow tubes were in good nick no cracks. R

Did you burnish the float tongues? Are you parking on the side stand or center stand?
Can you identify which drain tube the gas is coming out of for sure?

Auuh. Bummer. :S
Steve

Your petcock should stop all fuel flow while the bike is parked. If it doesn't you either got the petcock set to Prime or it's leaking internally. Sometimes when the petcock diaphragm fails it allows fuel to back flow down the vacuum line and into the carb. At any rate, you may want to inspect the petcock carefully just to be sure you are chasing the proper problem.

Sage advice.
Steve

Did you burnish the float tongues? No, will take care to do so.
Are you parking on the side stand or center stand? Centerstand.
Can you identify which drain tube the gas is coming out of for sure? Each line will get its own collector tonight so I can isolate.

I am gonna check fuel height again as I suspect this is the culprit. Is it possible I have a bad float? They look like solid rubber.
R

I put them in water to see if they all float the same.
Steve

The petcock was rebuilt a couple of months ago and the fuel tank was off the bike for several weeks with gas in it without any leaks. When I did clear tube, I used the tank as an auxiliary tank just with a longer gas line. No leaks out of the vacuum port which was bare in this capacity. The PRI position works and when not on PRI the bowls would empty w/o leaks continuing on the bench. I made many switches from PRI to RES to manage the clear tube test on the bench. I suppose I cannot verify the ON position isn't leaking as the tank was low so I needed RES but I doubt it. I am a patient person and this will get fixed, I do not believe in contempt prior to investigation. It's no doubt a man made perfect imperfection. I am guessing float height is high. When the carbs go in the 550 I have the air box needs to be lifted/moved about a 1/2" upward to bolt up its holders on the frame. This would suggest these carbs are not 100% level when on the bike. On the bench I use 100% level with bowl line. Will check on the bike and report back. I am also no wondering if my petcock vacuum line is bad. I think that woudl also the gas to drain in the manner you mentions. Mmmm, I am using the 35 year old one. It runs damn good when it's not leaking gas. Hahahaha. R

Yes and an easy check. R