Outer Limits 4x4 Board

Anyone use a gravity feed carby (eg. off a bike) on there 1.3 with the standard mechanical fuel pump and how did you overcome fuel pressure problems? I would have thought a fuel regulator would work but everywhere i look there are people whinging they dont.

put the whole bike motor in =)

look on pirate
they use regs

get a harley carb as they work ok or go to http://bbs.zuwharrie.com/ and see what they do

boner59 wrote:get a harley carb as they work ok or go to http://bbs.zuwharrie.com/ and see what they do

Ive had a look and no one seems to get them to run right?
http://bbs.zuwharrie.com/content/topic,81164.0.html
http://bbs.zuwharrie.com/content/topic,82802.0.html
http://bbs.zuwharrie.com/content/topic,82612.0.html

Anyone know if something like a serge tank to supply fuel would work? eg.

i dont know if it will work?
but it may be hard to keep it at half full as you will have to match the electric pump with the mech pump and then you will loose fuel out the bottom at varying rates,
or does the electric pump stay on all the time and only pick up fuel when the level is high enough

and if the top if full of foam does that mean the mech pump can pressurise the cell when it gets just over half?

I have no idea about this, I'm just curious
ashley

Instead of mucking about with motorbike gravity fed carbs, why don't you use a carby or 2 or 4 off an outboard motor.

Think about it...
They are cheap from marine recyclers..
They are designed to run off a mechanical pump.
They already have a float and needle/seat.
They are what you'd call a performance carby.


OR..

Mount your fuel tank on your roof.

Jas.

Simple idea i would have to give a try is throw a 'tee' piece between the outlet of the fuel pump and carb. Place a rather large restrictor in the pipe between the carb (maybe 1mm ID?) and tee and the other side of the tee to the tank return. Obviouly this tank return line must be pretty big to avoid too much pressure at the carb.
So im assuming this carb has no metering device at all?

want33s wrote:Instead of mucking about with motorbike gravity fed carbs, why don't you use a carby or 2 or 4 off an outboard motor.

Think about it...
They are cheap from marine recyclers..
They are designed to run off a mechanical pump.
They already have a float and needle/seat.
They are what you'd call a performance carby.


OR..

Mount your fuel tank on your roof.

Jas.

My old man has owned a few harley shops and has draws full of old carbs so it wont cost me anything.
Im pretty sure if i made a tank kind of like what i drew ,that one wont work for several reasons now i look at it, and mounted it over the carby on the side of the rocker cover it would work and if it dosnt work it wont cost me anything other than time. Floatless fuel bowls for holleys (Sand dragging mod) use a electric scavenging pump to remove the fuel from the bowl and they dont have any problems flooding, so i cant see why something similar wouldnt work to feed the carbs.

This is how to setup a floatless bowl.

yeah im doing this at the moment got a holley 4psi adjustable reg and had 2 put the stage 3 jet kit thro it 2 cope with the no longer having the vacum of the air box
the kit comes with lighter springs slides 4 sets of jets from 124-128-150-155 so of course we have put the 155 as they reconmend the 150s or 155 if u r running induvidual pods
im running a set of kawasaki zx10 ninga carbs if i remember right they have a 40mm throut
theres a write up i have done on here if ya willing 4 a read
http://auszookers.com/index.php?name=Fo ... pic&t=4369

If its any help I could never get my 38weber to run with a reg it did drop the pressure but dropped the volume aswell.
As suggested try a restrictor with a return to the tank then the carb will use what it needs but return the rest.
Just a thought.
Nik

I use a holley regulator and a electrical pump to feed my quad gsxr carbs. So yes it would work