Topic: CB550F Petcock help.

[FunJimmy]

I just removed my '77 CB550F fuel tank to replace the petcock with what I thought was the correct (two vertical outlet) SuperSport petcock and found that the treaded spigot on the bottom of the tank is too small to thread on the CB550F petcock that I purchased. In the removal process, I damaged the screen as well and now I’m unsure of what to do.

How can this CB550F tank have the smaller threaded spigot than the other ’75 CB550F that I own?

Is there another vertical outlet petcock that fits this small thread spigot?

Your help, suggestions and comments are always encouraged.

Cheers
FJ

[Gaither]

FWIW

If yours is like my '77 CB550F the outlet is verticle. You may not find one for the F. However, I found an NOS petcock for a '77 550K on ebay - the outlet is horizontal - toward the rear. Otherwise, they are identical! Fortunately, I had just enough length in the fuel line that it matched up OK. Why Honda used 2 that nearly alike for the F and K in '77 is beyond me!

Just do a search on ebay. When I bought mine, 2 - 3 months back, NOS petcocks for the F were readily available. It is, however, obsolete from Honda.

Good luck!

Gaither

[Gaither]

Forgot to mention, the "in-tank" screens were also available on ebay.

Gaither

[fastbroshi]

Jimmy, your petcock has the two small screws on the front?  I've heard you have to be very careful with those, in case you're rebuilding it.  If it leaks, new ones are the cure and they're kind of an oddball size, big surprise.

[FunJimmy]

After looking about, I'm starting to think that I have a '78 tank.
I know they look the same, but the bung on this tank is considerably smaller than on the '75 CB550F with the dual outlet petcock.

[TwoTired]

The 77 models both F and K went with the smaller tank bung (5/8 I think).  Same as the 750 K & F. 
The 77 was a single outlet with a "T" to feed both carbs ( The K only had one fuel nipple for the PD carbs, same as the 750s with PDs).
My 77 still has this arrangement from the factory.

The 75 and 76 F models had dual outlet valves and used the 3/4 tank bung.

I don't know which tank filter you damaged.  But, they are different between the 3/4 and 5/8 tank bungs.

Cheers,

[FunJimmy]

TT

Thanks for your thorough response.
I damaged the 5/8” fuel screen, and find that they are still available from the dealer.

How does the fuel hose route from the petcock to the carbs on your ’77 CB550?

Thanks again
Jimmy

[Flying J]

I think i had swapped in a 78 750F petcock on to my 77 550f.

[FunJimmy]

I think i had swapped in a 78 750F petcock on to my 77 550f.

Does the outlet point sideways or down?

[Flying J]

um... the 750f points sideways. I think. And the 550 points down... right? is this a quiz?

[TwoTired]

How does the fuel hose route from the petcock to the carbs on your ’77 CB550?

The outlet nipple goes straight down. There is about a 3 inch hose which then connects to a T.  One branch of the T goes through the carb common plate  hole and feeds carbs 1&2.  The other branch of the T travels over through the hole in the carb common plate and feeds carbs 3&4.

It's about as direct as it can get.

Cheers,

[Gaither]

FWIW

On my '77 CB550F the orig petcock outlet was down - verticle. The NOS "k" petcock I used as replacement was horizontal - toward the rear of the bike. Otherwise, they are identicle and interchangable - at least on this bike. Both were single outlet.

If some had dual outlets I'm glad I didn't run into that. I would have just plugged one of 'em. I had enough trouble verifying they would interchange [by email] before I bought the "F" petcock on ebay.

As it turned out, I didn't need a petcock. I was chasing fuel when it was electrical the whole time. A long, crazy series of events! But, you folks bailed me out. It's all on "Quiting on the road and a blown main fuse"!