Bike Carb Info

[Guest mdav1970]

I have done this video to show the pipes so if someone could watch and tell me for sure what the pipes are please.

 

https://youtu.be/-LbIDDIpFns

[maccavvy]

I asked the same thing a few years ago when I fitted my carbs

 

Do you know what bike they are off ,they look very similar to my cbr900 carbs. but yours are spaced mine have the manifold made to fit as it.

 

The lower blue pipe IS FUEL IN... the rest vent to atmosphere.Make sure you have a pressure regulator or a bike pump

[steve in stockport]

Bottom pipe is fuel in, the pipe you blow into in the video is the breather from the float bowls and the reason they seem connected is that without any fuel in there the floats are down allowing the air to flow back through the valves and out of the fuel pipe. Connect the fuel pipe and fill the float chambers and you won't be able to blow back through that pipe. The third pipe is a breather to allow the diaphragms to move.

The only pipe work you need to keep is the bottom blue fuel feed, the others can be discarded and left to vent to atmosphere or you can pipe them into your air filter if you want to.

Before you connect them all up take them back off the engine, remove the float bowls and give them a good clean inside. There will be bits of crap in there that could stop the floats seating properly and then you'll end up with fuel coming out of the pipe that you blew into. When you take the bowls off make sure you use a good, new long shafted screwdriver and don't let it cam out in the screw, they're made of cheeses and will round off before you know it.

[tractor]

yes bottom blue pipe fuel and the other smaller connections look like the water circuit so dont bother with those and the top two must be wot the others have said and are both vent pipes

[Guest mdav1970]

Thanks guys for the replies. I already run a facet pump with an adjustable fuel regulator with the Weber so this should be fine to use. I'll change the blue fuel pipe with proper fuel line as not sure if the silicon pipes are good enough for a fuel pipe.

[Guest mdav1970]

Another question please.

 

Do the carbs need to sit at a particular angle? as iv'e read a few topics where they indicate the carbs are sat at the correct angle. My manifold is straight out so the carbs sit very flat to the engine and do really have any angle. I know this is for the floats to sit correctly in pots, just not sure if sitting flat would be an issue.

[cb750]

I've always understood that the float bowl joint should be parallel to the ground. That way you get the correct fuel level.

[knights_templar]

Bike carbs will only work correctly if they are at the same angle as the bike they are designed to fit. There is no way to change that, so the intake angle is important.

[Guest mdav1970]

Ok i shall see if the joint is parallel which should then see the floats hanging correctly in the chambers. If its not i can always make a bracket to pull the carbs up to the required angle.

[Guest mdav1970]

How do you get the floats out? The fuel feed valve is stuck in one of the chambers so the float wont swivel and i cannot see how to get the small metal rod the float swivels on off as theres a bar in the way?

[Guest mdav1970]

Solved it via this video

[Guest mdav1970]

I have finally managed to find the time to setup the bike carbs on the car and they run.

 

2 problems i seem to have is:

1. When i accelerate it's slow to return to idle even though the throttle will snap back on the cable closing all 4 butterflies
2. 2 out of the 4 carbs seem to be sucking in more air than the other 2. I can put my hand over the trumpets and feel the air sucking in but not on the other 2. Will look for an air leak but i have tightened all the jubilee clips to the max.

[tractor]

have you balanced the carbs yet cos sounds like they are out

[Guest mdav1970]

What's the best way to carry out the balancing?

[tractor]

http://www.ebay.co.uk/itm/MOTORCYCLE-CAR-TOOLS-CARBURETTOR-CARB-BALANCER-VACUUM-GAUGES-GAUGE-2-4-CYLINDER-/272179932713?hash=item3f5f302e29:g:yBsAAOSwepJXVplMthis is wot I use

Edited June 22, 2016 by tractor