Author Topic: What tube is this? (Read 1789 times)

Sething · « **on:** November 02, 2018, 08:46:42 pm »

Could someone please identify this tube? It’s semi-clear and has a plastic connection. I know it ran down below the swing arm along with the carburetor exhaust tubes. I forgot to label it. Please assist. (And it’s not a snake)

Honda 1977 CB750K

Don R · « **Reply #1 on:** November 02, 2018, 08:55:14 pm »

battery drain?

754 · « **Reply #2 on:** November 02, 2018, 09:06:08 pm »

Gas tank overflow I think.. for a F model with door over gas cap.

Sething · « **Reply #3 on:** November 02, 2018, 09:06:22 pm »

Thanks Don. I think you nailed it. I changed to a lithium battery so I don’t need it, which is why I probably didn’t label it.
Thank you!

Honda 1977 CB750K

Bankerdanny · « **Reply #4 on:** November 02, 2018, 10:02:46 pm »

No, Frank is right, that is the back half of the tank overflow drain tube. The front half runs along the inside of the fuel tank saddle and the plastic connector pipe at the top of the photo should plug into the back of the hose under the tank where it emerges between the tank and seat.

seanbarney41 · « **Reply #5 on:** November 02, 2018, 11:50:05 pm »

Quote from: Don R on November 02, 2018, 08:55:14 pm

battery drain?

absolutely nothing to do with the battery

madmtnmotors · « **Reply #6 on:** November 03, 2018, 10:04:41 am »

Quote from: Bankerdanny on November 02, 2018, 10:02:46 pm

No, Frank is right, that is the back half of the tank overflow drain tube. The front half runs along the inside of the fuel tank saddle and the plastic connector pipe at the top of the photo should plug into the back of the hose under the tank where it emerges between the tank and seat.

+1

This fuel overflow drain was used on the later models with the fuel door, i.e. CB750A, F, K7/K8 to route spillage into the fuel cap "sump" to the ground instead of onto the top of a hot engine.

Sething · « **Reply #7 on:** November 03, 2018, 10:14:26 am »

Thanks everybody. I’m going to check on both. Really appreciate this forum!

Honda 1977 CB750K

Don R · « **Reply #8 on:** November 03, 2018, 04:16:12 pm »

They are probably correct. I'm K oriented.

754 · « **Reply #9 on:** November 03, 2018, 04:36:13 pm »

You are disKOriented, 77 and 78 K have them..

Are you 392 and 410 intolerant ?

Tracksnblades1 · « **Reply #10 on:** November 03, 2018, 06:49:24 pm »

On my F1 750, it's the bottom half of the Tank vent hose as Frank said.
When removing the tank on mine that line and fitting is left standing vertically near the battery vent hose. My new battery doesn't require a vent hose either but I had to leave it in there.

Don R · « **Reply #11 on:** November 03, 2018, 07:20:59 pm »

Quote from: 754 on November 03, 2018, 04:36:13 pm

You are disKOriented, 77 and 78 K have them..

Are you 392 and 410 intolerant ?

Actually I'm a big F model fan. I even still own the F'nK I built for my brother. It was a 77K and has it's 392 engine, I have a 78 410 engine waiting for it's APE backcut trans. K top end and an 1124 rotating assembly.

Sething · « **Reply #12 on:** November 03, 2018, 09:46:26 pm »

Hi guys. You guys crack me up!
The plastic attachment on the line fits perfectly with the old battery. I think we’ve got a winner.
I apologize for not making it clear that this is a Honda 1977 CB750K, not F. This is my first build.
Thanks again for the quick replies.

Honda 1977 CB750K

754 · « **Reply #13 on:** November 03, 2018, 09:56:55 pm »

Ok in the future you have to tell us the outside size..

ekpent · « **Reply #14 on:** November 04, 2018, 05:03:31 am »

Usually a battery hose does not connect with a hard plastic fitting. I'm sticking with the rest of the guys and going with the gas tank overflow/water drain hose. That hard fitting is made to easily disconnect it when you remove the tank.

Little_Phil · « **Reply #15 on:** November 04, 2018, 05:20:08 am »

If the hard black pipe has a ridge on the o/d at both ends (to aid the grip of the pipe that is pushed over) and a bump in the middle then it was the fuel overflow drain. Even if someone has used it on the battery.

Vintageguy · « **Reply #16 on:** November 04, 2018, 06:04:26 am »

It is the gas tank overflow which will work beautifully with bike on the side stand with a full tank.

flybox1 · « **Reply #17 on:** November 04, 2018, 06:18:30 am »

+1 for gas tank overflow.

Sething · « **Reply #18 on:** November 04, 2018, 07:25:22 am »

After inspecting the bottom of the tank and the Clymer manual, there is a tube that is supposed to run from the bottom of the tank to another connection, then runs below the bike as an overflow. I have a feeling this was not connected when I bought the bike and started to disassemble it, and may have been attached to the battery by the previous owner.
Now I need to replace the tubing cuz that thing has definitely seen better days! Then I’ll attach it to where it is supposed to be.

Honda 1977 CB750K

Stev-o · « **Reply #19 on:** November 04, 2018, 07:27:36 am »

Quote from: 754 on November 03, 2018, 04:36:13 pm

You are disKOriented...

Need to enter that in the SOHC Dikshunary, Frank!

flybox1 · « **Reply #20 on:** November 05, 2018, 10:59:28 am »

That hose nipple on the underside of the tank is to drain any spillage from the tank filler lid area, straight to ground. No stops.
This is an important safety item. If no hose here, your gas falls right on a hot engine.
Thats kindofa bad thing

Sething · « **Reply #21 on:** November 05, 2018, 11:10:45 am »

Thank you. I just ordered a hose and will be installing for any overflow to be directed under the bike.

Honda 1977 CB750K

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Author Topic: What tube is this? (Read 1789 times)