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Getting ready for synchronizing the carbs

exactly my point. you aren't going to fit a temp. tank 100's of feet up! 2" or 2 foot is not going to make any difference whatsoever when connecting it to the carbs.
 
This has become more of an academic discussion but I think the point here is that the higher you raise the temporary tank the higher the pressure on the float bowl seats. Raising it higher then normal puts additional pressure on the seats and MAY cause them to inadvertently leak. The 100's of feet scenario is an exaggeration to prove a point, but I'm glad that you at least accept the concept of hydrostatic pressure. In reality increasing the height by 1 meter only puts about 1.02 PSI more pressure at the float bowl seats. The formula is:

p=hPg where

p = pressure (N/m2, Pa)
h = depth at which the pressure is measured (m)
ρ = density of liquid (kg/m3)
g = the gravitational constant (9.81 m/s2)

For gasoline the density (P) is: 719.7 kg/m3

At 1 meter height you get:

p=1*719.7*9.81=7.060257 kPA or about 1.02PSI

Sorry, I love math and physics. Spelling... Not my strong suit.

This may not seem like much, but that's more then what the seat was designed to hold back.
 
p=hPg where

p = pressure (N/m2, Pa)
h = depth at which the pressure is measured (m)
ρ = density of liquid (kg/m3)
g = the gravitational constant (9.81 m/s2)

For gasoline the density (P) is: 719.7 kg/m3

At 1 meter height you get:

p=1*719.7*9.81=7.060257 kPA or about 1.02PSI


ok everybody, next time you want to knock up a temporary tank to balance your carbs, make sure you follow this formula strictly. otherwise it wont work as the hydraulic pressure will blow your float valves to bits. YOU HAVE BEEN WARNED!
 
Glad you understand it now. Keep in mind that we started out with this as your original statement:

where does the hydraulic pressure come from?????? it is atmospheric pressure acting on the fuel, which will be the same if the temp. tank is 2 inches above the carbs or 2 feet!
Click to expand...

From there we are now debating on whether that extra 1psi will really make any difference.

The truth is it may or may not. Just depends on how high you place the gas container and how weak your float bowl valve is.
 
Anybody want to buy $1 plans for a diverter valve from the nitro bottle to pressurise the float bowls. You can put the gas on the roof if you want but will need the solid float conversion kit at $200 plus tax. :rolleyes:
Here's a brain teaser. Is the fuel level different when the gas tank is full or empty and if not, why? :)

I'm getting ready for carb balancing as soon as the last shim turns up. I'm just above .03 on three valves and a whisker below on two.

My old '83 Carbtune is dusted off and ready - just need new adaptors. Correct me if I'm wrong but they are 5mm, yes?
 
Brendan W said:
Anybody want to buy $1 plans for a diverter valve from the nitro bottle to pressurise the float bowls. You can put the gas on the roof if you want but will need the solid float conversion kit at $200 plus tax. :rolleyes:
Here's a brain teaser. Is the fuel level different when the gas tank is full or empty and if not, why? :)

I'm getting ready for carb balancing as soon as the last shim turns up. I'm just above .03 on three valves and a whisker below on two.

My old '83 Carbtune is dusted off and ready - just need new adaptors. Correct me if I'm wrong but they are 5mm, yes?
Click to expand...

I think it's 4mm, but not sure.
 
tkent02 said:
I think it's 4mm, but not sure.
Click to expand...

That's what I thought too, measuring by candle light with my old eyes and the piece of knotted string but Mr Carbtune tells me that it's 5 or 6 and quote ' there are no 4mm used by anyone' . :confused:
Which reminds me to start another thread about the bleed screws - 7mm or 8mm ?
 
If your talking about the ports to measure vacuum to sync the cabs they're 5mm on an 850 too.
 
Thank you very much everyone or as we say in these parts - Go raibh mile maith agaibh go leir :)
 
Steve said:
"Bleed screws"? :-k

The ones on the brake calipers?

They use an 8mm spanner.

.
Click to expand...
Hi Steve,
They're the ones - well at least most of them still take an 8mm . A PO has moved one on to the mole grips phase of it's life. Parts suppliers tend to list replacements by thread size and pitch.
It's near on eight weeks in to this project now and my wife and I have enjoyed every minute and mile 1500. I am breaking every ain't broke don't fix rule but I know I have to go in because well you know why I have to go in. What I don't want to do is put myself off the road because the green eyed curiosity takes over and makes a really stupid move - again.
Haven't ridden for two days waiting for the tyres that got sent to the wrong shop :rolleyes:. Just won't go out on the old ones anymore - now that would really be stupid.
 
Brendan W said:
Parts suppliers tend to list replacements by thread size and pitch.
Click to expand...
True enough. Since you are looking for thread info, not spanner size, I am going to have to GUESS that it MIGHT be M6 x 1.0.

I can verify that when I get home this evening.

.
 
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