Author Topic: carbs leaking out overflow tubes  (Read 3173 times)

0 Members and 1 Guest are viewing this topic.



Offline MikeJW

  • Enthusiast
  • **
  • Posts: 163
carbs leaking out overflow tubes
« on: July 31, 2010, 10:24:15 AM »
When I first got my cb750, 3 of the 4 carbs were constantly leaking gas from the overflow tubes even after I adjusted all the float heights. When I examined the little brass standpipes in strong sunlight, I saw that they were split almost from bottom to top...undoubtedly from some water being in them over a cold winter. I tried to pull them out of the bowls, but saw that I was going to damage them. I went to the local Hobby Lobby and purchased a package of brass tubing for a few dollars. The size is critical. I bought 5/32 in. OD. I cut pieces about 1 mm less than the exposed part of the standpipe in each bowl. I made sure there was no burr on the inside of the cut pieces and then tapped them down over the standpipes. It got a little tricky towards the very end because they fit so tightly. After the first one, I thought about cutting them a little longer and then trimming them later. I don't think it makes much difference as long as you don't end up with something longer than the original. It is very important, however, that you have a nice square cut on the bottom end and you drive it down all the way. In my case, they fit so tightly that I never had to do another thing. I never had another drop leak out and I believe they will last the life of the bike...especially if I make sure to drain all the gas out of the carbs when freezing weather comes in the winter. Really an easy fix.
1972 CB750K2



Offline last_cb750

  • Full Member
  • **
  • Posts: 6
Re: carbs leaking out overflow tubes
« Reply #1 on: July 31, 2010, 05:42:30 PM »
what year/model bike?
78 CB750K
75 CB750K (sold)



Offline MikeJW

  • Enthusiast
  • **
  • Posts: 163
Re: carbs leaking out overflow tubes
« Reply #2 on: July 31, 2010, 06:41:53 PM »
1972 cb750 K2
1972 CB750K2



Offline dusterdude

  • Really Old Timer ...
  • ******
  • Posts: 6,879
Re: carbs leaking out overflow tubes
« Reply #3 on: August 02, 2010, 06:20:10 PM »
ive been thinking about doing that to mine too,now i think i will
mark
1972 k1 750
1949 fl panhead
1994 converted 883 sportster
1998 cbr600 f3



Offline lucky

  • Really Old Timer ...
  • ******
  • Posts: 6,627
Re: carbs leaking out overflow tubes
« Reply #4 on: September 15, 2011, 12:39:51 PM »
Very unusual problem thats for sure.



Offline Paul Lowe

  • Enthusiast
  • **
  • Posts: 117
  • If you like then it is good...
Re: carbs leaking out overflow tubes
« Reply #5 on: October 02, 2012, 06:38:05 AM »
neoprene tipped bowl float needles worked for me.
My Honda sickness deepens

CB350F 1972
CB750 K1 1971
C102 1963
C50 1968
C70 1972
C90 1974
CL90 1968

1/2HP electric bike home made...



Offline 6adan

  • Hot Shot
  • ***
  • Posts: 367
  • 70 CB750 JDM,75 GL1000,79 GL1000,79CBX, 95 GL1500
Re: carbs leaking out overflow tubes
« Reply #6 on: February 06, 2013, 08:57:23 PM »
You can also solder them. I have done it on my 70 and just had to do it on my CBX.