Vacuum hose routing under Fuel Tank

fjahandari

I'm new to this list but been around riding since 1984. I have nice non California 1997 carbeurated US Model with 25 k miles.
I've rebuilt the carbs, Synched and all and everything is running perfectly on my 1997. It runs great on an Auxiliary tank so its NOT the carbs or anything complex. However, when I hook up the regular tank there is next to no fuel flow. I've removed and looked at thye trank, the petcock and all it seems all is well. EXCEPT the vacuum line, breather etc. Fuel Valve is on "ON" position and that's not the problem.

None of the Owners Manuals (OEM or Haynes) has a clear graphic or photograph of how the vaccum lines hook up and route etc. There is a "T" junction between the vacum hose and the breather. Does it matter which hooks where? I've spent 3 hours trouble shooting this area; ironically it took me less to rip carbs, clean, sych etc.

PLEASE help by sending me a photo or a decent schematic of how they hook up. Or any ideas or suggestions! Very frustratedly yours!

Thanks.
FJ
Email direct dadashee@gmail.com

XXNUTZ

Hello, I had a similar problem last year and it turned out to be the diaphragm in the petcock being split. Even with vacuum being applied, it did not allow fuel to flow to the carbs. I replaced the entire assembly and haven't had a problem since. I'm having suspicions that the split came from the Ethanol in the fuel around here. As far as the hoses go, the vacuum line goes to the back of the petcock assembly for the diaphragm, the large overflow and breather just go down towards the ground off the bottom of the tank. I too have not found a good diagram of this hose issue. I took the T fitting off mine because the way the hoses were routed I was getting fumes, vapor and sometimes liquid fuel coming out of them. I routed it next to the overflow hose down towards the ground like it was on my old Suzuki. All it is, is a breather. If you check on the forum, there is a post on this subject with pics. Hope this helps, Cheers. P.S. Welcome!!

__________________
1998 CBR 1100XX Blackbird (Black, of course),PUIG Touring Windscreen, Corbin Gunfighter saddle, Two Brothers C2 Aluminum Oval Slip Ons.

fjahandari

xxnutz- Thanks for giving me a response. Does the vacuum connection from the back of the fuel petcock go to the vacuum port that is open, and located in the engine block right below the intake manifold where carb no 2 sends air/fuel into the valvues? I'm referring to the only one of the 4 on a cbr1100xx that does not have a screw blocking it and is open to the atmosphere by a long rubber hose? I was using these to synchronize the carbs previously. If so, I think we have a clear answer.

If so, its seems its totally different to what you have done... not that I'm debating; far from it. I'm trying to understand the entire concept first. Then, we can see the details etc and are potential work arounds.

Hopefully I can learn something here, then go to the fix.

ArmyStrong

and good luck on the fix!

__________________
Murphys 6th law of combat operations:
If it's stupid but it works, it ain't stupid.

Banshee

Yes, the vacuum port on #2 connects to the back of the fuel tap to actuate the vacuum valve for fuel flow. The hose with the T junction is the tank breather and the long single hose would be the overflow.

Post #4 in this thread has a good pic for you: vacuum line

fjahandari

indeed and that resolves that entire debacle and..... ahhh ... say 4 extra hours of gasoline infused intoxication in a garage in the hot summer...
Some things are so 'easy' and so potentially obvious but are they?
:-)

XXNUTZ

Banshee beat me to answering your question. It seems that you found and resolved your issue. The vacuum line does go from the block tap from under the #2 carb up to the petcock. The larger hose from the bottom of the tank is an overflow and just goes towards the ground. The original configuration of the breather hose came from the bottom of the tank (other side of petcock from the overflow) to a T fitting, two hoses came off that and basically went around in circles and vented to atmosphere. All I did was deleted the T fitting and routed a longer hose from the tank down towards the ground next to the overflow. My old Suzuki was like this. I have had no problems with this setup. Hope this clears any issues and you can enjoy your new found Love of the 'bird. We all do here. Cheers.

__________________
1998 CBR 1100XX Blackbird (Black, of course),PUIG Touring Windscreen, Corbin Gunfighter saddle, Two Brothers C2 Aluminum Oval Slip Ons.

Strek

Welcome from the windy city.

Catenaccio

Welcome from SE Nevada!

DragonXX

G'day from Australia
Glad you got that sorted out !

__________________
" 'Birds of a feather, flock together "

Quote of the month: "When the pupil is ready to learn, a teacher will appear." - Zen Proverb