Fuel Pressure, Fireblade

[blade_runner]

I was wondering what fuel pressure other fireblade owners use? The only Data I can find is from a Haynes manual, which does not give a pressure but a flow rate, the standard set up in a bike has no fuel pressure regualtor, just a low pressure pump. According to the manual it says the pump should deliver at least 900cc of fuel per minute.

 

Now heres a Question for the mathematicly minded.

 

What pressure should I set my fuel pressure regulator to?

The carbs require 900cc /min

the fuel pump is a Facet SS503 25 gallons /hour at a pressure of 6 to 7 Psi

 

25 galls/hr is roughly 113.5 litres an hour, which would be 1.89 litres a min, but i presume thats with the pump running at 6 to 7 Psi, so can anyone work out what pressure I should knock it down to ? to get to 900cc/min

from what I remember I'm running about 1.5Psi and on the odd occasion when looking down the carbs when its running I see fuel slowly bubbling from the Emulsion tubes as if the float chambers are flooding, or is it a case of TADTS? the float level seems fine when I checked it, so is the fuel pressure over comming the float valve? Can anyone shed some light?

 

 

Steve

 

'Pinky Pics' here

[Foxy Smith]

Yes I can but I need to look at me book. What carbs are you running??

[Foxy Smith]

For Keihins supplied by fuel pump a max of 3psi is suggested on the regulator. However more critical is the size of the float valve and they give a table.

 

Float valve size (mm) HP per carb gravity feed HP per carb 3psi pump feed

2.0 20-28 29-37

2.4 24-34 37-50

2.8 33-41 Not recommended

3.2 39-50 Not recommended

 

 

Sorry this is a bit of a back to front way of looking at it.

 

I'm running my fuel regulator at 2psi from a big hairy a*sed Facet pump and don't seem to be overcoming the float valves.

 

Maybe you need to look at the size of your float valves?

[Paul Thompson]

Pressure is very low 1.5 psi to 2 psi .

[blade_runner]

I didnt think about the size of the floats, just assumed they were standard, will have to pull the carbs off and take a look, the engine runs well its just sometimes at idle as i have said I've seen fuel bubble up the emulsion tube, doesnt do it all the time. but I thought I better look at it as i'm off the Switzerland next month and I'm currently getting around 25 mpg, anything I could do to improve this would help!

 

Edited to say; i'm running the standard Keihins, but with a dynojet kit using 128 mains and the standard 40s idle jets set to 3 turns out. with the Air correctors blocked off.

 

Edited by - blade_runner on 21 May 2005 06:42:40

[7Nut]

Take the car to TTS ❗

[blade_runner]

I could afford TTS tuning if i wasnt goin to Switzerland !

 

'Pinky Pics' here

[elie boone]

Blade_runner, Why not buy a sec. hand bike fuelpump it would make things easy'er.

[blade_runner]

I have though of going down that route, but i think the pump on a blade bike is gravety fed and does not have to lift fuel from the tank.... I have tweeked my fuel pressure down a little and it seems to be ok now

 

'Pinky Pics' here

[elie boone]

Blade runner, i doubt that the pump would not overcome the 25cm height of the tank and that only when its nearly empty. If you can mount the pump at the lowest level possible it will need even less suction power.