Fuel flow requirements 1100 slabby

[crow]

I'm thinking about putting a quick connector in the fuel line to make getting the tank on & off a bit quicker, something like this which is pretty universal on modern bikes

However those bikes are all FI and I'm wondering if it will be overly restrictive for an old skool carbed bike.

In the interests of science I did an experiment to measure the flow rate and found that the 5/16" rubber hose will flow ~7.8l/min but the connector setup takes that down to ~1.7l/m.

Problem is I don't know what the actual demand is. It's to feed an 1109 through RS36 carbs. Does anyone know what kind of flow rate is necessary?

I'm also not sure whether to add an in-line filter - I tested one of the typical cheapo ones as below and only got 0.6l/min though it  Any recommendations where to find something less restrictive?

Cheers!

[bunk]

I just use the filter on the pingle tap, nothing inline or in the carbs. No quick disco, just turn the tap off and run er til she quits. Kiss.

[Upshotknothole]

It's been my experience that RS38s are pretty close to the limit of slingshot petcocks. Pretty sure that big of a drop in flow with RS36s will have you draining the bowls on full throttle. Quick disconnects aren't a bad idea, but you'll need a larger one that flows better. 

[Dezza]

Use two in-line quick-break connectors instead of the single T-piece quick-break connector, one on each of the two feeds from a normal T-piece. You'll then have quick-break without any potential restrictions.

[rodneya]

I have a 2 outlet pingle with two inline connectors like that and have had b=no issues with RS36's. If I remember correct, there were two sizes available when I ordered them.

 

[crow]

I've managed to take some more measurements with some interesting results:

5/16" hose = 7.8l/min

Plastic inline filter (3mm bore) = 0.6l/min

Quick connector = 1.7l/min

OEM tap = 0.7l/min

Pingel Guzzler (claimed) 211oz/min) = 7.9l/min

Pingel Power Flo (claimed) 90oz/min = 3.4l/min

So the OEM tap is nearly as restrictive as the cheapo in-line filter. Interestingly the FI style quick connector, although restrictive compared to a plain hose, is still more than capable of handling the OEM tap flow rate.

 

[crow]

Despite the OEM tap seeming like a fairly pathetic dribble in comparison to the others it doesn't seem right to me that Suzuki would undersize it so much that a slightly bigger carb would struggle. So I did some sums:

Assuming a fairly rich AFR of 12.6:1 that means 1g of fuel is needed for every 12.6g of air

Air density at sea level 1.225kg/m3

Fuel density ~750kg/m3

So 1 litre of air = 0.001225kg, 1 litre of fuel = 0.75kg

Or looking at it the other way around 1kg of fuel = 1.33l and 1kg of air = 816l

Which means in terms of volume the air-fuel ratio would be 7734:1

For a 1.052 litre engine, to fill each cylinder once (1 complete cycle) = 0.000136l fuel

At 10,500RPM = 10,500  intake strokes / min = 2,625 complete 4-stroke cycles / min

Multiply that by the fuel requirement per cycle =0.4l/min

That would suggest that the OEM tap with a stock engine has plenty of headroom, which makes sense to me. Even with some allowance for other inefficiencies I'm surprised it can't keep up with a slightly increased demand.

Those who have had issues running the standard tap; what's your engine spec and riding conditions? And what symptoms did you see?

 

 

 

 

 

 

 

 

[Gixer1460]

That level of nurdiness made my brain hurt  

[crow]

55 minutes ago, Gixer1460 said:

That level of nurdiness made my brain hurt  

Actually it's spelled "nerdiness"

And I can't help it

[Ted M]

Love the maths mate. I think that the standard tap is closer to the limit than your sums suggest as you haven’t taken into account the inertia of the air/fuel mixture which will increase the amount going into the cylinder.