Topic: Two Fuel lines One Outlet on Petcock

[gwallis]

OK.... so once again I am going to show my ignorance.  When I bought the 1976 CB550 it came with two gas tanks...one leaked and the other was covered in rust but was spotless inside.  Neither of these tanks were on the bike.  So when I removed the carbs I really had no idea as to how the tank and fuel lines hooked up.

Now I am putting it all back together and I see two fuel lines coming from the carbs but only one spout on the petcock.  Am I missing a 'T-Connection' of some sort?  Is one of the lines a vacuum line?

Any help in this matter would be greatly appreciated,

Gary

[gwallis]

I just bought a new petcock for a 1976 CB550F and it only has one spout.  And when I look at the diagram for the 1976 CB550F it shows two fuel lines coming from the carb holder.

Can someone confirm that the 1976 CB550F has just one spout on the petcock.

Thanks in advance!

[Stev-o]

My '76 550F has one line coming out of the petcock, goes to a tee, splits and two lines feed the carbs.

BTW - the fuel line size is 5.5mm, I use 3/16" and its a good tight fit [like she likes it!]

[MCRider]

Just FYI: Somewhere around 74-75, the CB750 switched from 2 nipples to 1 nipple and a T. Something like that happened on the 500/550s as well?

[gwallis]

Guys... 'Thanks'... I appreciate all the help from this forum... it makes everything so much easier when you get the benefit of everyone's knowledge and experience!

And Stev-O... I hear you big time!!!

'Thanks again',

Gary

P.S.

Now where can I buy that 'T - Connection'?

[BollarNPS]

hate to piggy back but i have the same thing on my cb650. this has cleared up my guesses on this one! thanks for sharing your problem . Is there a good place to purchase this "t" part what im seeing is like 10 dollars. and would you happen to know the hose size for the 79 650s? if not thanks anyways!!

[MCRider]

hate to piggy back but i have the same thing on my cb650. this has cleared up my guesses on this one! thanks for sharing your problem . Is there a good place to purchase this "t" part what im seeing is like 10 dollars. and would you happen to know the hose size for the 79 650s? if not thanks anyways!!

The OEM fuel line is 5.5mm (7/32"). This presents the problem of procurement. Most common is 3/16 (too small) or 1/4" (too big). Both will often work, force the 3/16 on or clamp the 1/4 in on. Ts can be found at any auto parts store for cheap.

But if you want the OEM fit, you'll need to buy OEM sizes from a dealer or online dealer.

[Scott S]

 Some 550's had a petcock and carbs with one line, some had duals. Looks like you've got a combination of the two.
 Honda never used a T fitting, but that's one way around it. Get a good brass one.

[MD]

After reading this thread I decided to do some math.

0.09375 x 0.09375 x 22/7 = 0.027611 x 2 = 0.055223

0.125 x 0.125 x 22/7 = 0.049087

The top line is the surface area of two 3/16" line.  The bottom is the area of one 1/4" line.  The two 3/16" can supply slightly more fuel.

-MD

[754]

0's had a petcock and carbs with one line, some had duals. Looks like you've got a combination of the twol

Some 550's had a petcock and carbs with one line, some had duals. Looks like you've got a combination of the two.
 Honda never used a T fitting, ut that's one way around.....

Honda never used a T fitting, but that's one way around it. Get a good brass one.

 If Honda never used a tee, how did the single outlet petcock get gas to all carbs?

[turboed13b]

0's had a petcock and carbs with one line, some had duals. Looks like you've got a combination of the twol

Some 550's had a petcock and carbs with one line, some had duals. Looks like you've got a combination of the two.
 Honda never used a T fitting, ut that's one way around.....

Honda never used a T fitting, but that's one way around it. Get a good brass one.

 If Honda never used a tee, how did the single outlet petcock get gas to all carbs?

They used tees my 77 550f has one.

[jonda500]

I guess the later PD carbs had a single fuel inlet... I wonder why the single outlet petcocks are readily available, but screw on dual outlet petcocks are as rare as hens teeth?

A while back, just after I swapped my dual outlet petcock as it didn't fit my '78 550 tank, I scored an original early model 550 supersport tank. My current favourite plan for this tank is to cut off the threaded bit where the petcock screws on, and weld on the same (but smaller diameter) bit from an old honda twin tank that I have so I can use the common readily available dual outlet petcock that many old honda twins use (which also happen to fit the '78 tank).
John

[jonda500]

"They used tees my 77 550f has one."

Does any one know where to get one of these oem honda tees - I have never heard of them until now??

Edit - Actually I believe Scott S, I don't think honda originally used a tee piece on any of the 70's CB550s at all!

[Stev-o]

"They used tees my 77 550f has one."

Does any one know where to get one of these oem honda tees - I have never heard of them until now??

Edit - Actually I believe Scott S, I don't think honda originally used a tee piece on any of the 70's CB550s at all!

Yes, it's on the '77 550F fiche:


    011   JOINT, FUEL
16235-657-000   001    Discontinued   

No longer available from Honda. Here's a brass one....


http://www.ebay.com/itm/Adapter-Fitting-Brass-Barb-Tee-0-22-5-5mm-Hose-For-Air-Water-Fuel-/151871358592?hash=item235c3d0680:g:DqwAAOxyHE5RugOc&vxp=mtr

[jonda500]

Hey Stev-o, good to learn that info and great to know that a 5.5mm diameter tee is available - have added that to my watch list! Thanks,
John

[Stev-o]

Hey Stev-o, good to learn that info and great to know that a 5.5mm diameter tee is available - have added that to my watch list! Thanks,
John

You're welcome, Jonda.  It's a little pricey, you may find a better deal, that's just the first one I ran across.

[Oz350Four]

If I recall correctly for the 72 CB350F a single fuel line goes to a T that is part of the "fuel rail" for the four carbs..??!!

[PeWe]

My CB750K6 -76 petcock have one outlet mounted on the right side (left)! The fuel line had a T-connection when the OEM carbs have 2 fuel inlets. Smoothbore carbs have 1 inlet, Mikuni TMR 2 again.

Now using older type of petcock with 2 lines when the Yamiya tanks have that design (69-74) with petcock on wrong side (right). Trickier when fuel suddenly starvs and need to switch to reserve and release throttle.

[Scott S]

0's had a petcock and carbs with one line, some had duals. Looks like you've got a combination of the twol

Some 550's had a petcock and carbs with one line, some had duals. Looks like you've got a combination of the two.
 Honda never used a T fitting, ut that's one way around.....

Honda never used a T fitting, but that's one way around it. Get a good brass one.

 If Honda never used a tee, how did the single outlet petcock get gas to all carbs?

 OK, then...technically, the "T" was part of the rack of carbs. I don't believe there was ever a "T" between the tank and the carbs.

[Scott S]

"They used tees my 77 550f has one."

Does any one know where to get one of these oem honda tees - I have never heard of them until now??

Edit - Actually I believe Scott S, I don't think honda originally used a tee piece on any of the 70's CB550s at all!

Yes, it's on the '77 550F fiche:


    011   JOINT, FUEL
16235-657-000   001    Discontinued   

No longer available from Honda. Here's a brass one....


http://www.ebay.com/itm/Adapter-Fitting-Brass-Barb-Tee-0-22-5-5mm-Hose-For-Air-Water-Fuel-/151871358592?hash=item235c3d0680:g:DqwAAOxyHE5RugOc&vxp=mtr

 Well, I'll be darned. I stand corrected. That's a new one on me. And that brass "T" is exactly what I've used in similar situations before.