Topic: 2 different petcocks same bike which one?

[xsmooth69x]

these 2 petcocks came off 2 different cb550 tanks

which one should i use?

one petcock has 3 outlet or inlet tubes

the other one has 2....

[TwoTired]

Do your carbs have two inlet fittings or one?

[xsmooth69x]

so the red part is the big 1/4 tube that carries the fuel for between carbs 1&2 and then 3&4

the the blue part is another tube that shares fuel? between 1&2 and also 3&4, this is a smaller tube

the there are these 90" things that come off the sides of 2&3 that i have no idea what they do

then obviously the purple tubes coming off the carb bowl that i have no idea where those tubes end up going either.....

[TwoTired]

so the red part is the big 1/4 tube that carries the fuel for between carbs 1&2 and then 3&4

Not 1/4 inch they are 5.5mm. And, that's why stock used a two output fuel selector.

the the blue part is another tube that shares fuel? between 1&2 and also 3&4, this is a smaller tube

Part of the bowl vent system; 3.3mm tubing.

the there are these 90" things that come off the sides of 2&3 that i have no idea what they do

Bowl vent air source.  3.3mm tubing routes down behind engine in front of swing arm

then obviously the purple tubes coming off the carb bowl that i have no idea where those tubes end up going either.....

3.3mm tubing routes down behind engine in front of swing arm

[xsmooth69x]

so other than the fuel lines everything just vents into the atmosphere under the bike?

also i used 1/4 they seem to work and fit great. used zip ties to secure it even more

autoparts store doesn't seem to like MM

so what petcock do i use?

1 has 3 out things and the other has 2 but they both came off of cb550 tanks

[TwoTired]

You MUST use clamps on the 1/4 tubing because the nipples are actually too small for 1/4 tubing.  It's optional with the correct 5mm.
Auto parts store does want to stock two items when people will buy whatever they stock.  It's up to the buyer to find the correct parts.

Lots of people jam square pegs into round holes.

I've no idea what the 3 nipple valve does.  It's not stock on any CB500/550 I've ever seen.  But, as you are doing, people will put whatever parts on the bike they happen to like at the time.

Cheers,

[xsmooth69x]

so do you know what the 3 nipple does?

[seanbarney41]

that 3rd nipple is for vacuum...no vacuum, no fuel flow...kinda like an automatic fuel shut off...except they go bad all the time and are kinda pita...I wouldn't try to use it given a choice

[xsmooth69x]

ok i guess ill rebuild the other one and use that....