Bike Carb Fuelling

[Beaver]

Yeh the carbs I have now have tubes from the overflows which could well be the factory ones, so will leave them on to start with. Helps any overflow keep of the exhaust anyway.

[kicker]

Isn't getting the angle correct just to make sure you have the right fuel level in the carb. I don't remember ever seeing fuel come out when sitting on a bike facing uphill, floats gon float. Old bike carbs often have worn float needles in them

[Ned]

if you change the angle, the float wont be high enough to close the needle valve before the fuel gets high enough to run down the overflow

[Ned]

heres a picture if it helps. This is what i found with mine anyway

 

[Rookie]

Kicker is dead right, the reason you have to mount some of them on an angle is because they are designed to be on that angle and hence the whole float bowl is tilted to make it level. If they are mounted at the same angle as stock and you have fuel coming out the overflow then you need to adjust your float heights.

[Beaver]

Agreed.

[peteretep]

ned your carbs probably just need a clean like stephens

[Spencer]

Na man all the fuel falls out when you ride down a 5 degree hill.

[mjrstar]

Or tilt the bike to go around a corner. I run an anchient su electronic pump and no reg and it doesn't leak. I am still working on jet sizes as I only run two carbs on the mini.

[KIRK]

^tilting bike at speed doesn't count. there's special physics forces going on. You tilt the bike at rest and it will not work as intended.

 

but I don't think you have to mount these carbs on the same angle as they are in the bike. You see the same carbs on different bikes at different angles. Float level is set by special motorbike builder guys with carb angle in mind. There's usually a special tool. But if you put it at same angle as bike then you ain't gota do no adjustments.

[sentra]

the logic was bending them would give you less bowl volume, and not knowing if that was an issue, tilting the carb itself was the the better 'fix'

[sentra]

this is all 10pm rush job anecdotal stuff, and agree they should be rebuilt, but

im curious to get find out what the correct body angle should be, seeing as it idles perfectly happy, but is super lean and not responding to jet changes at all, i suspect a lol-durr moment to be had in that area

[sentra]

i only just realise the depth of spencers comment,

yeah that.

[KIRK]

should be fine withen a certain angle range just needa bend float tab/hinge/whatever  a little to make needle work properly. I suck at explaining but you'd understand if you come to work with me and mow some super slope lawns lol. I can adjust victa float in like 2 seconds so I don't get fuel starvation or flooding on big hills

[Steelies]

never underestimate the depth of spencers comments.

[sentra]

i met his mum one time tbh

[Beaver]

Right, bring this back from the dead.

Im having issues with fuel and I would like some thoughts.

What I think is happening is that because the carbs were originally gravity fed (when on the bike), the fuel pump is over powering the float valve and not shutting properly.

When I run the car with the pump removed it purrs, but if the pump is hooked up it turns into a sack of potatoes and overfills the carb and they overflow (out the overflow in the bowl).

I have come up with two options.

First - run a low presure self regulating electric pump, 1-2psi operating rang which the way understand it wil drop in pressure when it senses a restriction (ie when the float valves are shut). Something like this http://www.fuelflow.co.nz/FF_cms_03/eshop?page=shop.product_details&flypage=flypage.tpl&product_id=68&category_id=28

Second - set up a return line of sorts (I think there are regulators, maybe even electric pumps?) that will allows a return line to be plumbed in so when the carb dont want gas, it just gets pumped back to the tank. I think this is more likely to work but is more involved. Even a T piece inline, or a filter with two outlets woudl work yeh?

Anyone offer any thoughts or knowledge on this?

[Ned]

Are your floats set properly and your needles seating and sealing well? Maybe you need a bit more of an angle on your carbs or adjust the floats?

[Beaver]

yes and yes. Angle has nothing to do with this ned.

[Ned]

OK, if you say so. I just suggested changing angle because I had the exact same issue and changing the angle if the carb fixed it, but that's cool.

Its easier to change the angle of your carbs than pulling them to bits to change the float level, just to try and see what happens.