Author Topic: Gas Leak on far right Carb  (Read 672 times)

0 Members and 2 Guests are viewing this topic.

Offline exf5003

  • Full Member
  • *
  • Posts: 90
Gas Leak on far right Carb
« on: June 26, 2012, 08:59:29 AM »
I have a 74 750K4 and this morning i turned the bike on to warm up like normal before going in to work.  It hesitated at first to start so i opened the choke a bit and fired it right up (closed choke of course).  As i left to get couple things and came back the bike was off.  I tried starting it back on and it wouldnt, even with choke.  I then noticed that my far right carb was spilling gas from the overflow tube and from top of carb. I quickly shut off the gas from petcock.  I ride the bike daily and rode it last night perfectly fine.
PO had pods on and said he completely rebuilt the carbs and had synced them and has been great with idle and smooth ride since i've had it (dont know what size jets used though). 
I'm thinking something might be jamming the float or stuck a little from stopping the fuel into the carb.  I'll have to wait til i get out of work to try anything, but the only think i know to do is to try and tap the carb body to try and release it.  I just want to ask what other things i can try before having to break my cherry and disassemble entire carbs :o?  If it comes down to it, can i just take apart that one leaky carb or do i have to pull them all together? Do i need rebuild kits or new gaskets if taken apart?
Also, is the overfilled carb the reason my motor wouldnt start back up? Did it flood the engine? if so is there anything i have to do before trying to start back up?
Sorry for all the questions, noob here with carbs but find it fun to learn and fix it myself.
Thanks in advance.

BrockSamson

  • Guest
Re: Gas Leak on far right Carb
« Reply #1 on: June 26, 2012, 09:16:23 AM »
I had the same problem but on a set of 1977 750k PD carbs. 

First just tap the bowl with the butt of a screw driver.  It should free up a stuck float.  It is just one of those things that can happen, but could signal a problem.

I opened up my carbs and the clip holding the float needle in place was backwards.  I flipped it around and put the bowl cover back on and never had a problem.  Not sure if it was related but the issue hasn't come back up once.

Offline Johnie

  • Really Old Timer ...
  • *******
  • Posts: 8,609
Re: Gas Leak on far right Carb
« Reply #2 on: June 26, 2012, 09:58:45 AM »
Agreed...try tapping first. If not, then you can just remove the float bowl on that one carb while it is on the bike. They you can get at the float pin and remove the float an needle to clean it. While it is off check the brass overflow tube in the float bowl. Those have been know to crack. Let us know how you come out. That is the cool thing about these carbs is you can pretty much get at it with the bowls off including checking the jets for gunk too.
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline flybox1

  • My wife thinks I'm a
  • Really Old Timer ...
  • *******
  • Posts: 14,301
Re: Gas Leak on far right Carb
« Reply #3 on: June 26, 2012, 11:21:17 AM »
first mistake.  believing your PO  ;D
if the tapping on the bowl will not get the float freed up, you should start with the top of the fuel system, and check your gas tank for debris, rust, etc.  wash and rinse with gas and pour it into a white pail. check for sediment that might clog carb innards. make sure its clean. carb work you do is free, so its a no brainer to remove them and check everything in there is as your PO said it was. no need to remove each one from their rack. keep them all together.
main and pilot jet clear, emulsion holes all clear, floats are to spec height, and possibly new float valves.
beer, carb cleaner, simple green and 1-2 hours max  ;)
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline exf5003

  • Full Member
  • *
  • Posts: 90
Re: Gas Leak on far right Carb
« Reply #4 on: June 26, 2012, 12:07:52 PM »
Thanks for the responses back, i'll definitely try tapping first and remove bowl if tapping doesnt help.  If i see signs of gunky carbs i'll pull them all to do a good cleaning, beer certainly help the process :D 
Will i need to sync them if i remove the float, needle, and jets to clean them out?
Also do you guys think that this overfilled carb was causing my engine from starting up?  do i need to do anything to help start it back up after i get the carb to work properly? thanks again.

Offline flybox1

  • My wife thinks I'm a
  • Really Old Timer ...
  • *******
  • Posts: 14,301
Re: Gas Leak on far right Carb
« Reply #5 on: June 26, 2012, 12:20:41 PM »
It's probably not a bad idea for you to vac sync them. At least youll know for sure they are right.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline lucky

  • Really Old Timer ...
  • *******
  • Posts: 6,717
Re: Gas Leak on far right Carb
« Reply #6 on: June 26, 2012, 04:23:04 PM »
Sometimes the PO cleans the carbs etc.,, but they do not replace the float valve and seat.

IF it is a all metal float needle It can get a groove worn in it and it may be non concentric. If it is a rubber tip float needle the rubber cone tip can get out of round or the rubber is hard and not fitting properly. When carbs get cleaned or rebuilt it is usually because they a ARE LEAKING from a overflowing bad float needle.

But some people think they can just polish the seat with a piece of steel wool and call it good.

Replace the float needles and seats and check the float measurement according to the book and never worry about it for 2-3 years or more.
« Last Edit: June 26, 2012, 04:26:31 PM by lucky »

Offline Johnie

  • Really Old Timer ...
  • *******
  • Posts: 8,609
Re: Gas Leak on far right Carb
« Reply #7 on: June 26, 2012, 04:39:08 PM »
If the carbs were indeed rebuilt properly and synced properly by the PO, you would not have to sync them again if all you do it take off the float bowls and check the jets. However, if he synced dirty carbs and you clean them you will need to sync them again as the jetting would have changed do to having clean carbs now.
1970 CB750K0 - Candy Ruby Red
1973 CB750K3 - Candy Bacchus Olive or Sunflake Orange
1970 Chevy Chevelle SS396 - Cortez Silver
1976 GL1000 Sulphur Yellow

Oshkosh, WI  USA

Offline exf5003

  • Full Member
  • *
  • Posts: 90
Re: Gas Leak on far right Carb
« Reply #8 on: June 27, 2012, 06:11:31 AM »
Tapping worked!  She fired right up with no leaks or drips of gas anywhere.  The fuel tank was lined but i checked the gas anyways and it looked clear.  I checked the petcock filter and no signs of debris there either, but it could have bypassed it.  Took her out for a nice test run and runs like normal.  My only concern is what happens to that piece of debris that jammed up the float?  i take it that it was flushed into the carb, but will it stay in the carb or get lodged up inside further?
Thank you all for the great advise it is truly appreciated!  I keep coming back to learn more and more everyday :)

Offline trueblue

  • A person who has had many interesting experiences, some of which are true, is known as an
  • Old Timer
  • ******
  • Posts: 3,124
Re: Gas Leak on far right Carb
« Reply #9 on: June 27, 2012, 06:33:11 AM »
You'll probably find that the float was just stuck down a little, my 650 does this, if I drain my float bowls I have to give the bowls a little tap so the carbs don't leak, but if they don't get drained I never have a problem.  Just a quirk of owning an older bike ;D
1979 CB650Z
Nothing can be idiot proofed, the world keeps producing better idiots.
Electronic Guages for your SOHC 4