Results 1 to 4 of 4
  1. #1
    CB750 New Member tarrelbeer's Avatar
    Join Date
    Aug 2020
    Location
    The Netherlands
    Posts
    2

    Bad carb leak after disassembling

    Hi people!

    First time on the forum. After owning and working on a CM400T for the last years im now working on a 1982 CB750f project (EU).

    While in the process of doing general inspection and maintenance using the FSM I cleaned out the bottom end of the carbs using carb cleaner and put in some new gaskets.

    After installing the carbs on the bike and turning on the petcock fuel started spewing out of the following spot at Carb 2:



    https://imgur.com/f1mkXD9

    Was not able to find a similar issue on the forum but before disassembling again and possibly messing up more, I could very much use your opinions/advice since it is not obvious to me how the leak could have started and how to fix it.

    This was not leaking before.

    Thanks in advance!

    EDIT: After pondering it some more, just realised that i've had to put a lot of pressure and pulling on the carbs to fit them back into the intakes, especially the sides, could this have caused this leak? Is there some kind of oring inside at the connection point of the fuel rail that can be leaking now?
    Last edited by tarrelbeer; 08-02-2020 at 06:03 AM.

  2. #2
    CB750 Guru amc49's Avatar
    Join Date
    Sep 2015
    Location
    Fort Worth TX.
    Posts
    3,080
    There are o-rings on both ends of the T there. You could have cracked the braze joint there too but not likely.

    Try it again, sometimes they leak until the o-ring gets exposed to solvent and swells back up to seal, wouldn't be the first time. I fill them up, turn off spigot and let sit 24 hrs. to check again if the old rings still used leak.
    Last edited by amc49; 08-04-2020 at 03:03 PM.

  3. #3
    CB750 New Member tarrelbeer's Avatar
    Join Date
    Aug 2020
    Location
    The Netherlands
    Posts
    2
    Quote Originally Posted by amc49 View Post
    There are o-rings on both ends of the T there. You could have cracked the braze joint there too but not likely.

    Try it again, sometimes they leak until the o-ring gets exposed to solvent and swells back up to seal, wouldn't be the first time. I fill them up and let sit 24 hrs. to check again if the old rings still used.
    Holy cow, I just checked it again and its bone dry now with the bike idling! I guess stupid questions don't exist, were it not for your reply I would have been digging in the carbs again by now and probably breaking it more instead of fixing. I'll be careful to check it some more but all seems fine for now!

  4. #4
    CB750 Guru amc49's Avatar
    Join Date
    Sep 2015
    Location
    Fort Worth TX.
    Posts
    3,080
    I deal a lot with old o-rings, you learn a few things about how VOCs (fuel being one) can affect rubber parts.

Similar Threads

  1. Carb leak, Help!
    By sellsme in forum The SOHC Garage (1969-1978)
    Replies: 2
    Last Post: 09-29-2014, 02:01 PM
  2. Is this bad or normal 81 CB750K
    By beardedhoneybadger in forum The CB750 Garage
    Replies: 1
    Last Post: 05-28-2013, 03:59 AM
  3. 79 cb 750k running bad
    By motopsycho in forum The DOHC Garage (1979-1983)
    Replies: 4
    Last Post: 05-11-2013, 05:53 PM
  4. how do you know that you have a bad head gasket
    By cafeken in forum The CB750 Garage
    Replies: 7
    Last Post: 12-20-2012, 11:10 PM
  5. I think my tranny is bad
    By wa-chiss in forum The CB750 Garage
    Replies: 14
    Last Post: 11-03-2012, 01:39 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •