Author Topic: Swapping Fuel Valves?  (Read 1428 times)

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Offline KB02

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Swapping Fuel Valves?
« on: January 22, 2010, 06:02:45 AM »
As I have been collecting parts for my K8 project bike the tank I have chosen in from a K2 (The classic lines just look so much nicer in my opinion). The K2 tank has two fuel outlets on the petcock and the K8 carbs only have one inlet. I have the second outlet blocked off right now with a plug. I am worried that A.) that is not the best choice, B.) it won't hold up in the long run, and C.) that enough fuel be able to flow through that single line if that petcock is designed to feed a 750 through two lines.

Is there a different fuel valve that will just bolt onto my K2 tank that has a single fuel outlet?

Thanks!
1978 CB750K Project
2000 Ducati ST2
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Offline Toxic

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Re: Swapping Fuel Valves?
« Reply #1 on: January 22, 2010, 06:57:14 AM »
Call the folks at Pingle http://www.pingelonline.com/ They may have something for you.

The K2 uses the two 6 mm bolts to hold the fuel tap on so I don't know if Pingle has an adapter for that.  I think most of their taps use a single spigot like on your K8.  I know that they have on that fits on your K8.   I agree the ealier tanks have nicer lines.

sorry that's the best I can come up with.

Anyone else?

Offline KB02

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Re: Swapping Fuel Valves?
« Reply #2 on: January 24, 2010, 05:23:03 AM »
Thanks, Toxic.

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1978 CB750K Project
2000 Ducati ST2
...and a pedal bike

Join the AMA today!!

My project thread Part I: K8 Project "Parts Bike"
My project thread Part II: Finishing (yeah, right) touches on Project "Parts Bike"

Offline Nikkisixx

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Re: Swapping Fuel Valves?
« Reply #3 on: January 24, 2010, 07:20:21 AM »
I am in the midst of the same project, and decided to block off the second outlet as well.  Measuring the ID of the carb inlet and the tank valve outlets they are the same - about 5/32.  I can't imagine that using a single line from the tank to the carb would starve the engine, but until the monsoon season ends I can't test this theory  ::)

Anyone else have some insight?
It is a proven fact that modifying a SOHC Honda in any way will bring on the apocalypse.

Offline mystic_1

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Re: Swapping Fuel Valves?
« Reply #4 on: January 24, 2010, 09:04:55 AM »
Take your existing tank, run the fuel line into a container, open the valve for 5 seconds, measure the fuel that came out.

Repeat with the new tank.  Compare the results.  This will tell you whether you're flowing the same amount of fuel.

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Offline Alan F.

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Re: Swapping Fuel Valves?
« Reply #5 on: January 24, 2010, 09:10:35 AM »
why not run two lines to a tee then run the third to the carbs?  That second outlet could be your reserve, but don't quote me.

Offline mystic_1

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Re: Swapping Fuel Valves?
« Reply #6 on: January 24, 2010, 09:16:20 AM »
why not run two lines to a tee then run the third to the carbs?  That second outlet could be your reserve, but don't quote me.

It's not.  On dual-outlet petcocks, one line feeds cylinders 1+2, the other feeds 3+4.

Reserve function is related to two possible inlets for fuel at the top of the petcock body.  Main inlet is the brass standpipe.  When fuel in the tank is below this level, you must change to reserve, for which the inlet is in the petcock body between the mounting screws.

mystic_1
"A ship in harbor is safe, but that is not what ships are built for."
- John Augustus Shedd

My build thread:  http://forums.sohc4.net/index.php?topic=68952.0

Offline Alan F.

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Re: Swapping Fuel Valves?
« Reply #7 on: January 24, 2010, 09:42:21 AM »

That second outlet could be your reserve, but don't quote me.

It's not.
mystic_1

And there you have it, thanks Mystic. It's been a while now since I bought a new petcock and forgot all I'd learned about them.

Offline mystic_1

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Re: Swapping Fuel Valves?
« Reply #8 on: January 24, 2010, 10:21:58 AM »
No worries, I think your tee solution is more elegant than capping off one of the lines anyway.

mystic_1
"A ship in harbor is safe, but that is not what ships are built for."
- John Augustus Shedd

My build thread:  http://forums.sohc4.net/index.php?topic=68952.0

Offline Nikkisixx

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Re: Swapping Fuel Valves?
« Reply #9 on: February 08, 2010, 04:39:25 PM »
KB02 - took my '78 with the new (old) '72 tank out today and it ran fine with the single line.  Rode it down the interstate from the on ramp by my house to the next ramp at sustained highway speed.  It didn't stumble or act like it was fuel starved.  I did read a thread about the first outlet (nearest the front of the bike?) on these taps providing a more consistant flow, so that was the one I used.
It is a proven fact that modifying a SOHC Honda in any way will bring on the apocalypse.

Offline Jim F

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Re: Swapping Fuel Valves?
« Reply #10 on: February 08, 2010, 04:41:40 PM »
I just got this today

2002 RC51 1000 (SP2)
1983 GS1100EC Suzuki
2002 998 Dukati (Customers Bike)
1992 KTM500 2 stroke
1975 CB750/836 Honda
1978 GS750/840 Suzuki