mystery gas-leaking carb hose

I am new to 1981 750 twin which ran great until today when I realized that I was leaking gas profusely. Upon further inspection, I found the gas to be coming directly from a series of hoses located on the bottom of the carb housing which lead to nowhere.. I could not find any where to connect or reattach them to other than each other. Is this a drain hose? It leaks even when it is idling but not when it revs..

Are you familiar with carb disassembly, cleaning, etc? Your going to need to adjust the float bowls. Allowing way too much gas into the bowls and overflow out the, well, overflows!

not familiar with carb disassembly etc but i have a manual coming in the mail. Is it possible for a novice to do such a job with the repair manual? what is the story with the hoses? are they like an overflow mechanism?

Oh and thanks! By the way!! I could never find a specific manual for the twin model... Will the four banger manual suffice? is there a twin manual?

also just realized that im in the wrong thread... sorry:unsure:

toof wrote:

Oh and thanks! By the way!! I could never find a specific manual for the twin model... Will the four banger manual suffice? is there a twin manual?

I've got a few different types of copies on my site for the '76-'79 KZ750 twin... HERE'S ONE OF THEM ...

The 4-cyl is in no way similar to the 750 twin... except for the fact that it's a motorcycle, that is...

:laugh:

First off,
The tubes coming out the bottom of each carb bowl are overflow tubes. Designed to harmlessly deal with too much fuel in the fuel bowl of the carb. So, it seems you have too much fuel in the carbs. That's basically (normally) caused by 1 of 2 things. Either the floats are adjusted very wrong and not stopping the flow of fuel into the carb bowl when they should or they are just plain 'sunk' and not stopping the flow of fuel into the carb bowl. The other possibility is that the shut-off needle valve is leaking. Of course, it also could be some other strange thing, which sometimes happens.
Anyway, with a good book I don't think it's rocket science to deal with this problem yourself. I have 78 KZ650 and adjusting the floats, per the manual is a real pain in the neck. But, it is doable. The needle valves, should that be the problem, are replacable. Most, if not all, carb rebuild kits come with new needle valves and seats. Carb kits usually run about $15 for each carb. I don't know how much floats usually cost. I haven't had to replace any yet (knock on wood).

Anyway, have fun with it. One of the things about having these old bikes is the pleasure (even though it is not ALWAYS pleasurable) of working on them. If you don't like wrenching on a bike, you either need a good repair budget or to get a different bike.

When I was getting my bike back on the road, my carbs were pretty persnickedy. I lost count of how many times I had to take the carb rail off the bike and tear down the carbs. However, once I got everything working, upkeep maintenance has been minimal.

Terry!

I just rebuilt my carbs on a CSR750 Twin, and it wasn't too bad. If you got the bike used, try to find out if the previous owner had replaced the jets with jets that were waaay too big, as was the case with my bike. Once that was taken care of, no more backfiring, no leaks, etc. I found 2 manuals for my bike on Ebay, so check there as well. Now a new problem has arisen and not sure what it is - lol.. Good luck!