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Gas leaking through carb drain

43K views 10 replies 7 participants last post by  Loudo 
#1 ·
Hi Guys
I am not a great mechanic and have had the bike for only a week.
Drove it to work a couple of days and been out on it say 8 other times with no issues.
Park it in the garage and for sure no leaking. This morning I went out for a ride and 10 blocks along I stopped to show my friend my new toy as he was walking his dog. After I stopped, we noticed gas pouring out the carb drain. I turned around and came home, shut of the gas, and checked around a little. When I opened the carb drain screw, it seemed to leak right where the hose meets under the carb. Any ideas would be much appreciated.
Other wise bike is in near mint condition.
Oh yeah, it is a 1970 cb350.
 
#2 ·
ctrider said:
Hi Guys
I am not a great mechanic and have had the bike for only a week.
Drove it to work a couple of days and been out on it say 8 other times with no issues.
Park it in the garage and for sure no leaking. This morning I went out for a ride and 10 blocks along I stopped to show my friend my new toy as he was walking his dog. After I stopped, we noticed gas pouring out the carb drain. I turned around and came home, shut of the gas, and checked around a little. When I opened the carb drain screw, it seemed to leak right where the hose meets under the carb. Any ideas would be much appreciated.
Other wise bike is in near mint condition.
Oh yeah, it is a 1970 cb350.

Hey man,
Don't worry I got you covered. I ran into the same problem about a year ago...I had no idea what I was doing, I honestly would just ride it to work (about 1.5 miles) and try and beat the drip...a little embarrassing when the sentry stops you 3 days in a row, "Sir, I'm no mechanic but you really should get that fixed." The only thing you need is a little (and I stress a little) liquid gasket...any NAPA or auto parts store will have you covered.

So here's the process... close the petcock, undo the float bowl screw, let the fuel drain, make sure the screw is clean (WD-40 will do), then just put a little liquid gasket on it and rub it in the groves, then just screw it in the carb...good as new.

The reason I stress the amount is because it could potentially break off & get into your jets...and that stuff in your jets will ruin your week & weekend.

That's my two cents.

cFogs out

BT
NNNN
 
#4 ·
rather than using liquid gasket, many automotive stores have small metric gaskets. take the drain screw in with the float bowl and find an o-ring that fits.

if its coming out of that tube, its only three possibilities.

bad drain plug o-ring, (get a new one)
cracked overflow tube (solder it up)
float issue (wrong height or dirty carbs making it not close, or maybe a leaky float)
 
#6 ·
No it is just leaking from the overflow.
It must be a float issue, or the needle is stuck. Just not comfortable opening up the carb as I have never done it before. When my friend has time, next couple of days, he will come buy and help me.
Is there a type of carb cleaner that can be added to the gas tank?
Just wondering, like for preventive maintenence?
Thanks
 
#7 ·
It is not hard to work on your carbs, just takes a little practice is all. you have to start somewhere...luckily you don't need any special tools.
This link: viewtopic.php?f=20&t=13542 is a pretty good read on how carbs work.
This link: http://www.cmsnl.com/honda-cb350-super- ... partslist/ is a good resource for all of the parts on your bike.
If you would like a detailed walk through on your carbs, let me know. I'm not a carburetor guru, but I can help you fix that leak.

mike
 
#8 ·
ctrider said:
No it is just leaking from the overflow.
It must be a float issue, or the needle is stuck. Just not comfortable opening up the carb as I have never done it before. When my friend has time, next couple of days, he will come buy and help me.
Is there a type of carb cleaner that can be added to the gas tank?
Just wondering, like for preventive maintenence?
Thanks

How long have you owned the bike & when did it start leaking?
 
#9 ·
I have two sets of CB350 carburetors where all four of the float bowls have hairline cracks in the brass overflow tube.

So it will never NOT leak so long as any gas is in the bowl.

This may be a different area than where you're leaking, but it's something to check out. I haven't thought up a handy fix for the problem just yet, but I just know that four of the six carburetors I own are affected in the same manner.

Here's a photo of a dirty carb bowl, but the part I outlined in red is where I have a crack running the length of the tube. Check that after you've cleaned your needle and seat.

 
#10 ·
hey luke, I had the same problem on the brass tube in my petcock, and on a different set of float bowls for a cx500. 3 of my 6 float bowls had huge cracks, some so bad the bike couldnt run. I just cleaned the brass tube off really well with steel wool/sandpaper to get it to bare brass, and soldered it up. I used 60/40 solder from radioshack and it seemed to stick to the brass really well. I even tried to pry it off using my fingernail and i scratched myself pretty good, so it's a very solid fix.

the only precaution is making sure to keep the solder away from the opening at the top of the tube, dont want to solder it shut.
 
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