Topic: 74 CB350F leaking carbs but runs great.

[Gordon]

Please tell me you're gonna drink that beer afterward, or we may just have to kick you out after only one post!

[Bwood]

First of all Your in the right place to find some great help with Your bike

They have gave You some great advice on things to check and do to fix the problem

One thing I found on this site and it helped a great deal is to check the tube inside the flat bowl these can develop a small hole in that brass tube and no mater what You do you will have a leak until you change THE BOWL
IF I REMEMBER RIGHT you PUT YOUR FINGER OVER THE HOLE ON THE BOTTOM AND BLOW ON THE BRASS TUBE IF IT LEAKS REPLACE IT

FOUND OUT ABOUT THAT HERE Fixed My  BUDDYS 350 FOUR carb leak


Good Luck

Bob

[Spanner 1]

Could I have a dollar from everyone who's read this post, Yeah?, Yeah?...I swear I'll put the money into SOHC bikes.....!

[CafeRacin350]

The reason everyone has read this post is cuz for some reason when I posted it, I was able to send it to everyone's email. I've fixed the Float bowl problem, it just needed cleaning, I think the needle seat was sticky.
Cheers!!

[the godfather]

Everyone loves to tear apart their carbs. Fine cracks in the overflow tube cause leaks as well. Pull the float bowl, attach a hose to the nipple, fill bowl with beer, cover the top of tube and blow. If you have bubbles replace your float bowl. Sometimes the leak is at the base and you can sweat the connection.

I was going to post this possibility but youve beat me to it. I had this exact problem last month.

[seaweb11]

6 pages.........
 I had 3/4 of a page before I was lucky enough to have my engine builder diagnose with my ticking being a wrist pin issue.
Had it and 2 rods replaced and I'm on the race track now.   Is it perhaps time to look inside?   I'm just saying.......

Just an observation, I know a bad sound like you, I don't know how to diagnose them

[mutt]

Aint read all the (great) advice but offer up something I found on a 73 550- one of the upright pipes in the float bowls- the overflow pipe itself- had an invisible crack in it, which caused that carb to piss fuel. Cover the outlet & blow on the pipe- NO air should flow. If ANY does, theres your problem. Fix? trip to model store for brass tube that slipped over existing unit, some JB Weld, & Im a genius.
Find a container big enough to hold all 4 carbs held together by the various bars & linkages- like a big bread pan. Strong solution of simple green, put it on a low boil a couple of hours. Bright shiney carbs! Then blow out orifices etc w/ air & carb cleaner. Reassemble (you kept all the individual carbs bits  seperate, of course....

[Kadett]

Wanted to add another voice here for cracked bowls and to thank everybody on the forum who pointed out this as a cause. I was dealing with a leak from my #1 carb on my 400F after a full  strip down and rebuild of the carbs. Despite a new needle, seat and float set it kept leaking out of the overflow pipe.

The cause was a crack where the overflow pipe joins into the inside of the fuel bowl. It is essential that you check the bowl by filling it with gasoline and seeing if it leaks. I have previously checked the bowl during the stripdown and rebuild with cleaning fluid and alcohol. These produced no leaks, only the lower surface tension of the gas can truly determine if the bowl has a leak.