wacko
XS650 Addict
There seems to be two rubber hoses attaching to my stock petcocks on my 79 xs650. I am switching to a custom tank and petcock. What do i do with the smaller rubber hose? Is it just a vent?
-
Enjoy XS650.com? Consider making a donation to help support the site.
XS650.com receives a small share of sales from some links on this page, but direct donations have a much greater impact on keeping this site going.
Petcock question
- Thread starter wacko
- Start date
-
- Tags
- carburetors
Q Tip
mad bomber
it runs to the vacuum barbs on the carbs on the stock bike. I have VM carbs on my bike so my stock vacuum petcocks can only be run on prime. Thus I have no reserve position.
If you are switching to manual petcocks you won't need the small hoses.
If you are switching to manual petcocks you won't need the small hoses.
cros36
thread killer
you will need a vented gas cap, and blind plug the barb on your carb.
bluebikerblan
Geezer
No, more accurately it would be an "air leak" to your engine intake. As others say...
remove the tubing from the manifold barb and blind plug/cap the barb.
BobberNick
XS650 Addict
Does anyone have a pic. to show the barbs? I am doing the same thing. I have a Sporty tank and petcock (Vented Gas Cap) running into a "T" splitters which fuels both carbs. Are the barbs the smaller brass fittings directly above the main fuel fittings or are they the really small fittings at the bottom of the float bowl? Right now I have hoses running from the smaller brass fittings directly above the main fuel fittings acting as vents and not tubing on the fittings at the bottom of the float bowl. I'm assuming the bottom fittings at the bottom of the float bowl need to be capped (Or they would spill fuel). thanks for letting me hack into this thread. It covered exactly what I'm working on right now.
The barbs everyone is referring to here are not on the carbs at all but rather on the intake manifolds. They didn't appear on the manifolds until the vacuum petcocks were introduced in '78. If your bike is older than that and you have original (or original style replacement) manifolds, then you will not have these barbs and don't have to worry about them.
The nipples on the float bowl bottoms are from the overflow tubes inside the bowl. Originally, they had clear plastic hoses attached that ran down behind the engine. This would dump any gas overflow onto the ground instead of on top of your (hot) motor. You can add hoses or just run with nothing attached. DO NOT PLUG THEM.
Jeeze, I'm constantly amazed that guys think they can build whole custom bikes from scratch when they don't know some of the simplest things about this bike or any bike in general for that matter, lol.
The nipples on the float bowl bottoms are from the overflow tubes inside the bowl. Originally, they had clear plastic hoses attached that ran down behind the engine. This would dump any gas overflow onto the ground instead of on top of your (hot) motor. You can add hoses or just run with nothing attached. DO NOT PLUG THEM.
Jeeze, I'm constantly amazed that guys think they can build whole custom bikes from scratch when they don't know some of the simplest things about this bike or any bike in general for that matter, lol.
5twins...................I think guys have been watching too many of the TV shows such as Orange County Choppers. They see a bike assembled and doesn't look to difficult. But using all brand new parts, versus 30+ years old parts, may yield different results.
bluebikerblan
Geezer
These are the vacuum line "barbs" on the carb holder manifolds that 5twins is describing above. They are where the vacuum line tubing is attached as the source of vacuum to open the fuel flow valve in the vacuum petcocks. If not in use and connected to the petcock they should be capped, plugged or otherwise sealled so that an air leak is not provided to the fuel/air mixture supplied to the engine from the carburetors.
The simplest way I know of is to use one of the line to "bridge" and thereby cap each of the barbs to each other. Preserving the barbs as a vacuum source for synchronization of the carbs.
Other lines coming to or from the carburetors are either vent/overflow or fuel supply lines.
There is of course also a short piece connecting the fuel supply of the two carbs.
Some wonderful informative reading with pictures and descriptions available here:
http://www.amckayltd.com/carbguide.pdf
The simplest way I know of is to use one of the line to "bridge" and thereby cap each of the barbs to each other. Preserving the barbs as a vacuum source for synchronization of the carbs.
Other lines coming to or from the carburetors are either vent/overflow or fuel supply lines.
There is of course also a short piece connecting the fuel supply of the two carbs.
Some wonderful informative reading with pictures and descriptions available here:
http://www.amckayltd.com/carbguide.pdf
Attachments
Last edited:
wacko
XS650 Addict
thanks for the info. The best part of these forums is the opportunity to learn as you go. I am super thankful for all that I have learned from those with mode experience who don’t feel necessary to belittle others. However there are others who are just old and retired 
bluebikerblan
Geezer
Wait a minute wacko....I may have a better idea than sticking each end of one of the former vacuum line pieces on each of the carb holder barbs....let me think a minute.
What could you do with that rubber hose???
Nah.....have a nice day! Best, Blue
wacko
XS650 Addict
Blue, great link.
Some very useful info for a rookie carb guy like myself. Much appreciated.
Some very useful info for a rookie carb guy like myself. Much appreciated.
Nubster
XS650 Enthusiast
Not to go too far OT...I want to replace the two non-vacuum petcocks on my tank. Where can I look to find QUALITY replacements? The ones on the bike now are junk and I don't want to just replace them with more junk.
BobberNick
XS650 Addict
Some people are just born knowing how to build custom bikes.. Its genetic. Doctors, lawyers, magicians, wizards, etc. Some people are just born as idiot savants. Others aren't lucky enough to have the title of savant... Thanks to the pos. Contributors on this site, it's possible for people to learn!
bluebikerblan
Geezer
So what bike do you have now, what tank and what petcocks? I personally like to rebuild OEM as I find them to be of better quality once the get well cleaned with new diaphragms, filter screens, gaskets and selector discs replaced. There are some pretty good previous threads to search. Have you tried that? Need more info.
Nubster
XS650 Enthusiast
Bike is a 79. Tank...no idea but not stock. Petcocks are different on each side. Couldn't tell ya if either is OEM for the tank. I did a search a while back but didn't really see any talk about quality replacements. I'll snap a pic or two.
right
left
tank
right
left
tank
Last edited:
bluebikerblan
Geezer
Oh crap....I was all set to give you some glib answer about replacing you stock OEM petcocks with something from Mikes XS like.....
Petcock - Non Vacuum type Petcocks - Non Vacuum type to replace 1978-84 vacuum type petcocks.
***WE ARE OUT OF STOCK TILL LATE AUGUST***
All 1978-84 North American market 650's have original petcocks operated by
Vacuum from a line to the intake (on carb holder). 1978-79 models have 2 and
1980-84 models have 1 petcock. Vacuum petcocks are chronic leakers and are
all getting to the point of being non-repairable. Our petcock is the Early type 650
manual petcock with a wider flange cast on it so it will fit in place of the vacuum
types. Our Petcock fits to right or left and each comes with the tap to tank
O-Ring seal and assorted outlet fittings ( petcock has 2 outlet ports).
Fittings included: 2 ninety degree, 1 Straight fitting & 1 outlet port Plug.
There is an "ON", "OFF" and "Reserve" position. Part #20-0019$44.00 USD Ea Add to Cart
Well bag that!
~~~~~~~~~~
Flipping back to my HD days, I'd probably try to find a way to adapt a Pingel to that tap thread.....Z-1 Enterprises perhaps or a raft of aftermarket accessory outlets. Probably would go with a single Pingel to a Y and feed both carbs. Never had or saw a Petcock I liked better than a Pingel. Best I can think of at the moment. Nothing stock OEM Yamaha I know of to fit that tank outlet. Best, Blue
Petcock - Non Vacuum type Petcocks - Non Vacuum type to replace 1978-84 vacuum type petcocks.
***WE ARE OUT OF STOCK TILL LATE AUGUST***
All 1978-84 North American market 650's have original petcocks operated by
Vacuum from a line to the intake (on carb holder). 1978-79 models have 2 and
1980-84 models have 1 petcock. Vacuum petcocks are chronic leakers and are
all getting to the point of being non-repairable. Our petcock is the Early type 650
manual petcock with a wider flange cast on it so it will fit in place of the vacuum
types. Our Petcock fits to right or left and each comes with the tap to tank
O-Ring seal and assorted outlet fittings ( petcock has 2 outlet ports).
Fittings included: 2 ninety degree, 1 Straight fitting & 1 outlet port Plug.
There is an "ON", "OFF" and "Reserve" position. Part #20-0019$44.00 USD Ea Add to Cart
Well bag that!
~~~~~~~~~~
Flipping back to my HD days, I'd probably try to find a way to adapt a Pingel to that tap thread.....Z-1 Enterprises perhaps or a raft of aftermarket accessory outlets. Probably would go with a single Pingel to a Y and feed both carbs. Never had or saw a Petcock I liked better than a Pingel. Best I can think of at the moment. Nothing stock OEM Yamaha I know of to fit that tank outlet. Best, Blue
Nubster the right one may be OEM. It may clean up enough to hold.
Take the cotter pin out remove the nut, and retension the spring.
Try some of the big box cycle places J + P cycles, J C Whitney etc. or ebay
for replacements.
Take the cotter pin out remove the nut, and retension the spring.
Try some of the big box cycle places J + P cycles, J C Whitney etc. or ebay
for replacements.
