Author Topic: Help. CB650 carb leaking fuel  (Read 627 times)

0 Members and 1 Guest are viewing this topic.

Offline parq

  • Full Member
  • *
  • Posts: 13
Help. CB650 carb leaking fuel
« on: March 20, 2022, 01:10:01 AM »
So was expecting a first year ride yesterday and my friend's CB650 carb was leaking fuel all over the place.

We managed to locate the leak from the T fitting (no 9) on the picture



Unfortunately I don't have the skills or confidence to take apart the carb.

I checked again today and the leak isn't that bad. A bit moist around the T fitting and def no dripping any more.
Until I find a garage who can do this work for me, are there any tricks I can safely use to remedy the issue?


Online PeWe

  • Really Old Timer ...
  • *******
  • Posts: 16,096
  • Bike almost back to the 70's 2015
Re: Help. CB650 carb leaking fuel
« Reply #1 on: March 20, 2022, 05:01:14 AM »
Learning by doing.
I had never taken the engine apart before first time I did it.
There are so much information available today on internet. Not only good manuals. People that describe with photos or videos how they did it.

 Mistakes to be done included.

As long as you have the feeling about how hard you can tighten a bolt, nut and understand that some parts are fragile it will go fine.

Fuel leak can end up in a fire.
« Last Edit: March 20, 2022, 05:02:52 AM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline parq

  • Full Member
  • *
  • Posts: 13
Re: Help. CB650 carb leaking fuel
« Reply #2 on: March 20, 2022, 09:11:19 AM »
Learning by doing.
I had never taken the engine apart before first time I did it.
There are so much information available today on internet. Not only good manuals. People that describe with photos or videos how they did it.

 Mistakes to be done included.

As long as you have the feeling about how hard you can tighten a bolt, nut and understand that some parts are fragile it will go fine.

Fuel leak can end up in a fire.

Yup crazy fire hazard.

So I massaged the area with my fingers.
There was nothing really anything loose and moving which was assuring.

Turned the pet cock on to better locate the egress. and magically the fuel leak had stopped.
Pet cock off/ Drained the bowl and pet cock on and it still holds dry.
Rock and tilt the bike.
Wait for several minutes and keep looking, and still dry.

Will keep monitoring and go for a ride around the block but I think it will be ok,
because we really couldn't figure out what was causing the leak.

I suspect Gremlins at play.
Fuel leak has stopped and if it's good still good the next couple of days I'll postpone the tear apart to post-riding season.
« Last Edit: March 20, 2022, 09:14:51 AM by parq »

Offline parq

  • Full Member
  • *
  • Posts: 13
Re: Help. CB650 carb leaking fuel
« Reply #3 on: March 20, 2022, 01:38:09 PM »
Took the tank off (which I should have done in the first place).
Gas hose was just about only sitting on the barb fitting.
Wow!
And the rubber is so old it cracks everytime I try to put it back on.

I wonder what the ID is for the OEM hose? Anyone? Looks like the prev owner used a 5mm ID which seems a little bit too small

Offline Alan F.

  • We remember the Night Rider, and we know who you are.
  • Really Old Timer ...
  • *******
  • Posts: 7,506
Re: Help. CB650 carb leaking fuel
« Reply #4 on: March 20, 2022, 02:34:34 PM »
 5.5mm ID hose, about 7/32".

You can get it at any Honda powersports or Honda Marine dealer.

Offline parq

  • Full Member
  • *
  • Posts: 13
Re: Help. CB650 carb leaking fuel
« Reply #5 on: March 20, 2022, 11:46:13 PM »
5.5mm ID hose, about 7/32".

You can get it at any Honda powersports or Honda Marine dealer.

perfect. thank you so much. ordered and will pickup later today w a new fuel filter.