TOPIC:

Nessism wrote: Float height is an inexact method of controlling fuel level in the float bowl. If done correctly it should get you close but there are a lot of variables in play. For example, if the weight of the float is compressing the float needle spring then you need to hold up the float while measuring, and that typically leads to inaccurate height measurements. Also, if the float needle spring is weak the needle seat pressure level won't be up to the proper level and the fuel level will be higher. Most Kawasaki FSM's don't even list a float height spec for this reason.

Going back to the photos, you have at least one carb with a fuel level noticeably higher than the others. Is this the carb that is leaking? If so, I'd address this first.

Ed, your question gets to the issue, as it relates to the carb angle position when leaks occur. The third pic was taken after taking the bike off the center-stand and leaning it on the side-stand.
It only leaks fuel while resting and (angled) on the side-stand, and only from left carb #1, which suggests the fuel level rises higher in only that carb bowl. I recall when draining the #4 carb, the amount of fuel that drained out was less than usual, after resting on the side-stand for several hours.

Patton wrote: Here, for reference, is an earlier thread seeking “clear tube” and “fuel level” information as to RS34 carbs (with excellent pics): www.kzrider.com/forum/3-carburetor/60229...-please?limitstart=0

The purpose of adjusting float height is to achieve the correct fuel level. Boo on Mikuni for inexplicably failing to provide a “service fuel level”. Which thereby makes it impossible to confirm whether or not the float height adjustment achieved its purpose.

One side question (probably stupid, I know) --- Is it positively certain that the tube shown below is an overflow tube and NOT a vent tube?

The reason for asking is that the Mikuni description includes the following:
• Float Bowl Vent: Allows atmospheric pressure into float bowl for fuel flow.
And I haven’t been able to find anything from Mukini that mentions an overflow tube or an overflow circuit in the RS series.

As gaskets sooner or later deteriorate, a service fuel level above the gasket is an open invitation to leakage past the gasket.
If Mikuni designed the RS Series this way -- again, Boo on Mikuni.
On the other hand, perhaps Mikuni deems frequent or routine gasket renewal to be acceptable with high performance racing carbs such as these.

BTW, does the top of the pictured tube exit into the carb bore? Hopefully not, especially if it's an overflow tube, as an overflow circuit should prevent raw gasoline from ever entering the carb bore in the first place.

Good Fortune!

I believe the tube pictured above is the overflow vent tube, which opens into the space above the fuel, between the floats
It vents excess fuel directly out the bowl bottom next the drain plug, where a flexible drain tube hose attaches.
My preference is to solve this drainage issue, so I don't have hoses running off to some obscure place to drain excess fuel. As it is, the drips land on the starter cover, and run onto the inside of the transmission cover, to finally drop off that to the ground below to create a deplorable little pool of fuel droplets.

Two bowl vents on each carb (one each side), I believe:

For reference:




Good Fortune!

Thanks Patton

Please Note: Patton's photo shows one of the four similar but different float bowls that comes with a four-carb set. Each bowl has at-least one feature unique to its position in the rack, and therefore are not interchangeable.

I'm ruling out the accelerator pump system as a potential cause of excess fuel accumulating in the left (#1) carburetor after reviewing the fuel passage pathways for that system, and the bowl gasket design. There is no way fuel can arrive in #1 float bowl, since it's path is sealed off by the o-ring bowl gasket, and there is no other related opening in the bowl for it to get there.
Will reset the floats higher, and clean the float valves and bores thoroughly (per Steve), and see what comes of that.

I have the exact same problem with my RS34s. I always refer back to this when I start questioning the RS carbs. RS carbs are designed to be on a race bike. Race bikes typically do not use side stands. This being said, I too have set my carbs to 17mm to combat this. I also turn my fuel tank off a couple blocks from home. I had planned on using the clear tuble method on mine. I was going to set them 1mm under the surface level.

Do you think that will lean them out? My 33's are sensitive to the levels.
Steve

swest wrote: Do you think that will lean them out? My 33's are sensitive to the levels.
Steve

Clear-tube result with floats set to 21 mm.
Bike on center-stand



30 mm. stacks w/Ramair filters:



I was a little nervous doing this, since it required NOT following directions...

Quadruple-checked and cleaned up the float valves and related o-ring sealing surfaces in the carbs, then swapped positions (greased the o-rings) and reset the float heights. I found that simply bending the float tabs further does not permit the tabs to press against the valve needle properly.
The float tabs now have a reverse-bend with slight curve to improve alignment with the needle, and prevents contact with the valve body.

And there's room to adjust the floats further if needed...

Keep in mind you need to run them for at least 100 miles before you can get an accurate plug reading.
Steve

That fuel level looks much better. Hopefully it will be low enough.

The fuel level isn't overly critical as long as the jets are covered. The level only has a small effect on the mixture while running.

Nessism wrote: That fuel level looks much better. Hopefully it will be low enough.

The fuel level isn't overly critical as long as the jets are covered. The level only has a small effect on the mixture while running.

Ran the engine a couple times, and she leaned on the side-stand all day without dropping a single drip.
Twenty-one millimeters!

Thanks for the consistent advice.

swest wrote: Keep in mind you need to run them for at least 100 miles before you can get an accurate plug reading.
Steve

About a hundred mile mix of highway, country road, and city. Mikuni 30 mm velocity stacks and Ramair foam filters on regular Shell gas. Plugs pulled immediately on return today, and photos taken about ten minutes later:

Can you do a 5th gear plug chop?
Steve