Equal Fuel hight?

[XS1100_OEM4ME]

Here is a thought and question? What would be the effect if you removed the drain plugs from all 4 carbs and connected them with a flow tube? We all know that equal fuel level is important for best performance and with 4 carbs there is bound to be "some" differance no matter how hard you try to adjuste them Has anyone tried this? and if so what is the result?

[DGXSER]

Theoretically not a bad idea. In practice though, with the float valves working to let fuel in each bowl as its level changes, and the movment of fuel as the bike leans from oen side to another, I am not sure it is truly ever going to work.

[James England]

Theoretically not a bad idea. In practice though, with the float valves working to let fuel in each bowl as its level changes, and the movment of fuel as the bike leans from oen side to another, I am not sure it is truly ever going to work.

Theoretically, it doesn't work at all. Let's say you have three carbs with identical fuel levels and one carb where the level is much higher. Let's say Carb 1 has too high a level and 2,3 and 4 are OK. In the usual setup, they all stop admitting fuel individually and three of them are OK with only one of them badly adjusted. If you link them all together, the float valves on 2, 3 and 4 will close as usual but, instead of cutting the fuel supply, they would be 'over-ridden' by the badly adjusted float on Carb 1, which would continue to admit fuel until its normal cutoff point, raising the level in the other three at the same time. So now, all four carbs have too high a level instead of just one.

If one of the float needles stuck with a piece of crud or whatever, in the normal setup, only one carb would overflow. If they were linked, the stuck needle would allow all four carbs to overflow because the other three float needles would be over-ridden by the stuck one.

Does that sound right?

[DGXSER]

James, the theoretical situation is that they are all four set in spec, operating correctly, just not 100% identical settings. This would get them all 100% equal.

In practicality, the bike leans and levels change, or any of your listed situations occur, or probably a dozen others that do not come to mind at the moment.

[ManagerMike]

Don't take this badly, but it sounds like the brilliant idea looking for an opportunity to go bad, like the highly vaunted yet much maligned YICS.

[3Phase]

Don't take this badly, but it sounds like the brilliant idea looking for an opportunity to go bad, like the highly vaunted yet much maligned YICS.

+1

Brilliant flames when it went bad.

[cywelchjr]

Think about the side stand. All the gas from all the uphill carbs flowing to the downhill carb and out onto the ground and onto the hot engine. Sounds like the type of situation *I* want to create with my bike . That's not even considering cornering and such, with all the fuel sloshing to the outside carb and things like that. I can see nothing but trouble with an idea like this. Frankly if this were something that might have worked, some smart engineer would have tried it (maybe they did, that would have been the cause of the test rider running off the track in flames ).

[James England]

James, the theoretical situation is that they are all four set in spec, operating correctly, just not 100% identical settings.

I don't understand what you mean. If all four carbs are all set in spec and operating correctly, why bother joining them up with tubes? Or, if you mean that all four end up in spec because they are linked together, that's incorrect....they will all have the same fuel level, determined by the individual float/needle which is set at the highest (and not necessarily correct) level. The level across the bowls will always be determined by the float/needle which allows most fuel in. Joining them makes it, from a physics point of view, one big bowl, fed by four individually adjusted inlets which close off until the one with the highest level finally shuts off. Yes, the solution would be "all four set in spec"..... which makes joining them pointless because......

.....when the bike's on the sidestand, the level of the one carb bowl (which is what they become by linking them) will be determined by the overflow in the carb nearest the stand ie the other three will empty completely (which they wouldn't do if individual, of course)

Theoretically, it's an awful idea which simply would not work. Next time I get a bank of four carbs, I'll do it and video it (unless someone beats me to it)..

[DGXSER]

First of all, I am not condoning it at all, or supporting the theory. Comunism is also great in theory.

The Theoretical situation, is that even with the float levels set in spec, they will each be just a touch different. After all, spec leaves a 1mm of play to begin with. So, you could set all four within spec tolerances, then measure fuel level and see differences. With the bike sitting nice and level and sitting still, all devices working correctly, you will still see some difference in fuel level from carb to carb. Not that I ever have gotten this anal about it, but it has been stated that it is recomended to use the tube off the bowl drain method and keep adjusting until every carb comes up 100% identical level with the tube method. This carb version of the YICS would correct that, under those ideal conditions.

But as has been thoroughly pointed out, once you change anything about it, including the bike no longer being nice and level, or sittign still, or any one component not workign correctly, it no longer works. And it could cause some serious problems.

So I would still say, nice in theory, but not in practice.

[XS1100_OEM4ME]

Good thoughts

Lots of good thoughts, remember, this was just an "idea" 1st, I do see the need for a shut off, kinda like the octy, when bike is parked to stop the flow. 2nd, gas would not flow from one side to the other in turns, the reason we lean the bike is to balance centrifugal force with gravity, that why the acid doesn't come out of a full battery when you turn to the side from the over flow (it is also why we don't fall off and hit the road when we turn) As to the one being too rich and causing all to be too rich, well that would need fixed even if only one is leaking onto the exaust or you could burst into flames anyway. It would take some work to make the shutoff valve, so more work then benifit I would guess, but it got some of us thinking

[DGXSER]

Don't get me wrong, we are past the level of physics I can completely evaluate in my head. But that centrifugal force could also force fuel to the outside carb.

Again, in theory a nice concept. And I would not say for certain it will not work. I have been surprised before.

[ViperRon]

Murphy's Law

The more complicated the plumming the easier it is to get a leak.

[melbxs]

So for this to work all the carbs need to be perfectly set up?

If all the carbs are perfectly set up then there is absolutely no benefit to be gained.

[James England]

So for this to work all the carbs need to be perfectly set up?

If all the carbs are perfectly set up then there is absolutely no benefit to be gained.

Yep. I mentioned that too in a previous post. If one carb is out on the OEM setup, you have one carb out. If you link them together then all the four carbs get the level of the last float to close... If this one is not adjusted correctly, then all four carbs are out. Not to mention two, if not three carb bowls emptying when the bike is on the sidestand (even if the floats are actually set correctly it will do this).