RoadkillUK
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| posted on 13/5/07 at 01:21 PM |
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Bike carbs leaking fuel
HELP 
We've just fitted some bike carbs to our 1600 crossflow using a facet fuel pump. When the ignition is on and the pump is pumping we have fuel
leaking out of (at least) one of these small holes.
CBR600 carbs btw.
Advise needed!
Roadkill - Lee
www.bradford7.co.uk
Latest Picture (14 Sept 2014)
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Catpuss
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| posted on 13/5/07 at 01:31 PM |
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Sounds like the float valve is not shutting properly and flooding the float bowls.
This could be due to one or more of:
Too much fuel pressure,
Float bowl height not set,
Carbs at and angle so float height is wrong,
Worn float needle or float valve,
Dirty float needle or float valve (bits of crud disloged when moving around carbs).
For the fuel pressure I guess you could run a pipe to the carbs with say a funnel up high and pour petrol to get gravity feed pressure. If that stops
the leak then fuel presure could be an issue.
If it does still pour fuel out then it may well be the float valve/needle. In that case have a look there. Make sure your carbs are at a decent angle
as it can affect the float height at which the valve shuts off.
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jacko
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| posted on 13/5/07 at 01:39 PM |
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Why not use a bike fuel pump that is made for bike carbs 
Jacko
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RoadkillUK
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| posted on 13/5/07 at 01:46 PM |
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Thanks, just looking for some fuel pipe so I can test the pressure theory (which is what we think it is).
As for buying a bike pump, we will if we have to but it is a locost after all 
Roadkill - Lee
www.bradford7.co.uk
Latest Picture (14 Sept 2014)
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ReMan
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| posted on 13/5/07 at 01:57 PM |
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Almosrt certainly over pressure.
A car pump will be too much for them and you've probably broken them now trying, so will have to bin them. Just joking, hopefully
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Surrey Dave
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| posted on 13/5/07 at 02:51 PM |
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pressure
I have a Facet pump and regulator , if I set the pressure anymore than 1.5 lbs the carbs flood.
I believe the bike pumps are pressure sensing and pump higher pressure but cut off when they sense the closing of the fuel valve.
I have one to fit but cant be bovvered!!
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jacko
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| posted on 13/5/07 at 03:08 PM |
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As for buying a bike pump, we will if we have to but it is a locost after all
Sell your pump buy a bike pump and save money  
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triumphdave
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| posted on 13/5/07 at 04:55 PM |
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I too have a regulator on mine,just a thought though are the carbs at the right angle on the manifold so the float bowls are level.
If you always do what you have always done you will always get what you have always got
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givemethebighammer
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| posted on 13/5/07 at 05:41 PM |
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Sounds like too much fuel pressure, I had the same problem with my Blackbird carbs - I couldn't get the pressure right with the facet pump and
malpassi regulator. Changed to an R1 pump and no regulator (cuts out when it senses back pressure in the fuel line). No problems since.
something like one of these will do the trick
http://cgi.ebay.co.uk/Yamaha-YZF-600-Thundercat-Fuel-Pump_W0QQitemZ190110861609QQihZ009QQcategoryZ10490QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.co.uk/Yamaha-FZR-1000-Exup-Fuel-pump_W0QQitemZ160114138986QQihZ006QQcategoryZ10490QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.co.uk/Yamaha-YZF-R1-4xv-fuel-pump-carbs_W0QQitemZ300110014691QQihZ020QQcategoryZ10490QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
[Edited on 13/5/07 by givemethebighammer]
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UncleFista
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| posted on 13/5/07 at 08:48 PM |
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Catpuss;
We've had the carbs apart again just for a check, all clean and the float valves seem to be closing fine. Also the carb float bowls are level,
so (as all 4 have been leaking) I'd agree and say the fuel pressure was too high
Jacko;
Looks like we're gonna go with a bike pump, we were just hoping that the low pressure pump we have would be OK
ReMan;
Bugger, broke 'em you say ? Damn, that's 99p ebay cash down the drain
Surry Dave;
Didn't know that, I thought they just ran all the time, but low pressure...
TriumphDave;
Float bowls are level
givemethebighammer;
Thanks very much for the links, if I look for one closer to home, I ussume injection pumps are different, and how do I tell an injection pump aprt
from a carbs one ?
Thanks very much all
Tony
Tony Bond / UncleFista
Love is like a snowmobile, speeding across the frozen tundra.
Which suddenly flips, pinning you underneath.
At night the ice-weasels come...
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