Topic: Carbs leaking on 77 cb750 k after rebuild

[walnut777]

i just had a local shop rebuild the 4 carbs on my 77 cb750 k. the rebuild was 3-4 weeks ago and they have been leaking for a week or so.
im so agitated with this at the moment. i hate even imagining leaving my bike at that shop after it took so long the last time.

im thinking of downloading a manual and fixing the carbs myself. the only experience i have with carb rebuilds are riding & push mowers carbs and some weed eater carbs.
 after reading some posts on here. it seems like it is most likely a float problem.
what are the hoses for that come out of the bottom of the carbs for? i figured they were puke tubes (overflow tubes).

any suggestions on what manual to read and any tips and tricks?

[bollingball]

Go to the download manuals at top of this page it says (69 to 78 Huge file) about 250meg best manual you will find these carbs are not hard to work on. I have a 750 K8 but they are all most the same. If you have any problems feel free to PM me glad to help. So are most people on this site. The screw at the drain bowl serves two purposes.With the screw closed it is in over flow mode if you open the screw about one or two turns it goes into drain mode.I have a few pictures if you need. But for sure download the manual If you have a clymers trash it.How clean is your tank and your in tank filter.

[walnut777]

didnt know i had an intake filter.
the tank appears to be clean. the pet cock is some homemade thing. im going to order the original petcock tonite.

i havent seen any screws on the bottom of the bowl just black hoses hanging from them. i suppose theres a screw in there?

[Spanner 1]

The first rule of owning an SOHC bike with some problem buggin' ya is to sit down , stare at the bike and drink a beer ( slowly )  ... Then post here   ....
Overflowing carbs is probably THE most common problem posted about here........ in your case, a non standard ( for your bike ) petcock could be all that's wrong. If your petcock will allow a very small flow of fuel flow while it is 'off' ( fairly common, actually ) , then the floats/float needles will be 'fooled' and allow the bowls to overfill and commence a cycle of leaking out the overflows.....

[bollingball]

If you buy the OEM petcock order the filter it slides over the petcock tube before you install it.
Here is a picture of the drain screw just above the brass tube your hoses are on those tubes simply divert the fuel from spilling on the engine.

[walnut777]

The first rule of owning an SOHC bike with some problem buggin' ya is to sit down , stare at the bike and drink a beer ( slowly )  ... Then post here   ....
Overflowing carbs is probably THE most common problem posted about here........ in your case, a non standard ( for your bike ) petcock could be all that's wrong. If your petcock will allow a very small flow of fuel flow while it is 'off' ( fairly common, actually ) , then the floats/float needles will be 'fooled' and allow the bowls to overfill and commence a cycle of leaking out the overflows.....

my bikeisnt leaking out the overflows. it seems to be coming out around the bowl gaskets and you can see gas dripping off the srews on the carbs. my wife left her camera at work, i was gonna take a pic of it

[bollingball]

Sounds like your float level is too high. I keep mine about 2 to 3 mm below gasket.Don't know if you can see the level in the clear tube. Click to inlarge. Think you can on #4

[dtmmil]

14.5mm seems to work for me on my settings, you may need new bowl orings also. Check ebay for po boy carb kit for 77-78 carbs, I have had good luck with them, georgefix is the guys name. The carbs aren't that hard to work on either, just look that way!

[Spanner 1]

Having your carbs rebuilt in some shop is all fine and dandy, but if you don't eliminate any rust flowing down form the tank at the same time then clean carbs become plugged carbs PDQ............ and leaky float valves too...

[NateMinn]

I got a 77 750K and I know your pain.

My last fix was very simple.
Find which carb is leaking, check the drain hoses, follow it back.
Turn off the gas.
Remove the bottom of the carb. Just a few screws.
Lift the black plastic bowl up and down and see if the needle is moving along with it.
If not, remove the float bowl, slide out the pin on the hing just like a house door.
Take out the pin, if it is stuck in there.
Check the black rubber cap on the needle.
Make sure it is on snug.
Mine on rare occasion work loose.
This is really very simple.
Hardest part is getting the 3 little screws out to take off the bottom of the carb.