Petcock... is it really needed.

[bkaushansky]

I’m in a quandry. Bike is all one off custom work and after putting the tank in place, I noticed I am really tight on space to fit petcocks since the carbs sit so much higher and have the control cable coming out of the top.

Rather than messing around and having to do more welding on a primed tank, what are people’s thougts on running without petcocks? The bike is a trailer queen intended for group weekend outings.

FYI, not worried about having to drain fuel for tank removal.

Thanks.
B.

 

[SiXS]

Some type of fuel shut off should be considered, If space is tight, try an inline fuel shutoff valve.

Si

 

[mrtwowheel]

Check out the Briggs & Stratton type inline shut off valves. Sometimes you just got to put hardware on a motorcycle. I don't get this "minimal" thing, after all, a motorcycle is hardware. No wires, no battery, no lights, no brakes, no controls, no cables, no mirror, none of that makes any sense to me. What's next? No frame, no tires, no engine, no wheels, no seat.

Scott

 

[gggGary]

Throttle cable elbows can help, sold many places. Shortening the cable sheath is is a PITA I used a cut off wheel in the Dremel VERY carefully. It sure does get crowded above the carbs.

 

[motormike]

w/o petcocks..the only " shut off " is the float bowl... if they fail.. then fuel will either go out the over flow tube or fill the crank case.

 

[CoconutPete]

"Throttle cable elbows" Gary? Where did you buy these? Now I'm curious. Mine "works" the way it is, but I think I could benefit form one of those elbows.

 

[grizld1]

It's usually both/and, Mike; fuel out the vents and into the crankcase. So OP, you're capable of "one off custom work" but you're not able to fabricate a simple adapter for a compact petcock? All it takes is a piece of 5/16" aluminum bar stock, a drill press, a 1/4" NPT or 3/8" NPT tap, a round file, a bit of gasket paper, a bit of Teflon tape, and some sealant. It's a simple job.

 

[gggGary]

"Throttle cable elbows" Gary? Where did you buy these? .

I bought 10 IIRC but they can be found There are 40.70, and 40 and a 90 degree versions.
https://www.amazon.com/Mikuni-VM-degree-cable-adjuster/dp/B0149KLVQS
I may just get all fancy and have motion-pro build up a complete cable to fit the VM's on the XS650 with carb end elbows.

 

[bkaushansky]

Gary... I wish I had that much space. I have intake runners that bring the carbs back by an inch. I have the angled exit and have tried working with cabling. Still no room.

Limited on space for inline unless I push things back into the space after the vertical frame support.

And yes... I can fab an adapter to rotate the output from the tank. Wanted the simplest solution. The bike is pretty minimal but that's the intent. This isn't a cruiser or daily.

If no other options available, I was going to build this and use a right angle barb. On that note, any benefit or negative to putting both fuel lines (left and right side of tank) into 1 petcock then "Y" feed to both carbs.

Thanks for all the feedback.
B.

 

[mrtwowheel]

Gotta ask, what kind of tank do you have with no bungs or adapter for a petcock?

Scott

 

[MaxPete]

w/o petcocks..the only " shut off " is the float bowl... if they fail.. then fuel will either go out the over flow tube or fill the crank case.

Check out the ding-danged words under my avatar photo. Those f@ckin' float-bowl thingies on my '76C model have caused me so much heartburn - I wouldn't trust them to shut the fuel off for too long if I were you.

Pete

 

[bkaushansky]

Gotta ask, what kind of tank do you have with no bungs or adapter for a petcock?

Scott

I used a 71 Tx650 tank as a core then went from there. The bottom portion of the tank is setup for the standard yamaha petcock, but as the project developed and tank mounting relative to carb postion came together, it was clear that I'm tight on space.

 

[bkaushansky]

Check out the ding-danged words under my avatar photo. Those f@ckin' float-bowl thingies on my '76C model have caused me so much heartburn - I wouldn't trust them to shut the fuel off for too long if I were you.

Pete

What carbs are you running? Assuming you've changed the float pin and seal.

 

[gggGary]

`Yes one petcock to to feed both carbs works fine. I'm redoing those petcocks right now, they were all redone and working perfect than sat with no gas for four years, dribble dribble.
I ordered a couple of these
https://www.banggood.com/8mm-Inline...p-1124152.html?rmmds=myorder&cur_warehouse=CN
will report when i get them here.

 

[grizld1]

I checked my 77 Standard tank to see how much range would be lost with a single petcock. After the tank was leveled and drained through the left tap, only 4 oz. remained when the right tap was opened. At 48 mpg, that's a loss of only 1.5 mi. There's now a dual spigot Pingel petcock on the left side of the tank and a blocking plate on the right.

 

[xjwmx]

The float valves are going to leak some. In use, it's fine if they leak as long as they don't leak faster than the bike burns gas.

 

[XSLeo]

As has been said many times the floatvalve IS NOT a shut of. It's a flowcontol valve. It controls the flow of fuel to maintain proper fuel level in the float bowl.
They are not fuel shut off valves. If they were then why do manufacturers use pet cocks?
Leo

 

[Paul Sutton]

Experience tells me to never trust a floatvalve, not even for a short stop to refuel. When the engine is running at idle the vibration seems sufficient to keep the floatvalves well seated, but turn the engine off and put the bike on the side stand then do not trust them.