Mystery of the overflowing carbs

So I have had issues with my beloved KZ650 B over the past few days. The carbs were puking a hell of a lot of gas. A full tank in 8 hours (overnight). Afer tapping the carbs, which has worked in the past, with not even a glimmer of hope of stopping the leak I decided to remove the tank. As I pulled the fuel line gas spewed everywhere. I thought to myself, the vaccume line is not connected so why is the gas flowing. I figured the 30 old petcock had seen its final days and decided to order a new vaccume pecock from Z1.

I ordered the new part from Z1 on Tuesday at 4:47 pm MST. I live in Calgary and wanted the bike to run ASAP so I expedited the delivery and much to my surprise it showed up on Thursday at 3:30pm. That is what I call service.

Anyways, I unbolted the old petock and cleaned the area with some wet/ dry sandpaper making sure to cover the bolt and tube holes so no grit would get into the tank. I added some plumbers tape to the threads of the bolts and bolted the Suzuki petcock on the tank. No leaks or drips, awesome!

After a couple of minutes of nursing the new fuel line and vaccume line onto the nipples, I gingerly squeezed the tank into position. A little harder than normal due to the nature of the new Suzuki petcock. It has its nipples rotated 90 degrees towards the seat. After a little tap the tank sat into position. The new lines are a little long, but that can be tweaked later. After priming the carbs and looking for leaks (there wern't any) I fired her up using the kickstart.

Volia, no more puking carbs. It was the stinking petcock the whole time. I thought I was goig to need to rebuild the carbs.

If something does happen in the future, then at least I can rule out the petcock. All in all a good purchase. It is too bad that you can not find new Kawasaki petcocks anymore. The Suzuki petcock works really well as a replacement.

KR

You may not need to rebuild the carbs, but you should figure out which one(s) is/are overflowing when the petcock is on. If you take a look at the overflow hoses, it's easy to find the culprit(s). Once found, you can drop the carb bowl and remove/clean the float valve needle and jet so it seals properly. Otherwise, you will still have an issue with the carb bowl overfilling when the petcock is open. Fortunately, cleaning the float valve assembly is not very difficult and doesn't actually require carb removal. Ed

Yea, this has been an area of debate here before. On a properly working set of carbs where the needles/seats are 100% perfect and working you could leave the petcock in prime all the time and not a drop of gas would ever leak out of the carbs. So yes you had a bad petcock, but also needles/seats that could use replacing. Yes you can try to clean them, but don't bother, just replace the bad sets.

KOOL RYDER wrote:

Volia, no more puking carbs. It was the stinking petcock the whole time. I thought I was goig to need to rebuild the carbs.

Yes and no. It's true that a petcock which seals off tight will stop the gas coming out of leaking carbs, but it's equally true that you can leave the petcock turned on indefinitely if the carb needles/valves are working correctly.

I'm not recommending it as a standard practice, but I can leave my petcock on as long as I want and they don't leak any gas. If the tapered ends of the needles are polished smooth and the brass seats are too (and the fuel level is set correctly), they will seal properly and not leak. I put the needles in a hand drill and polish the tapered end with 600 paper. I put the brass seats in and polish the seal surface with a Q tip and chrome polish. Get them smooth and they will seal. IMHO, doing that polish is standard maintenance if you want them to work right. I do it at least once a year.

The use of vacuum cut-off petcocks eliminates the possibility of leaking, but the carbs should not leak unless the needle valves are not shutting off well.