RS 34 Float heights, Wet vs Dry

Getting my RS 34 ready to install , have replaced jets, bench Synched, today checked float heights dry all at 17.5 mm.
On the bench stand did the wet check, all fuel levels way too high, number 2 carb was just dripping fuel from the overflow.

After 4 adjustments finally got the fuel levels down to just under the gasket face, to achieve this i am at 23 mm on the float to carb face.

I will go with the wet level test, but curious as to why i have ended up with being so far offf Mikuni spec ?
Im sure a lot of folks dont check using the wet test , any info or thoughts on why such a big difference to achieve the correct fuel level ??
Thanks

I had the same issue on my bike and learned that each float is not going to be able to carry its own weight and especially after age they will lose their floatability. Therefore doing the wet test is more accurate.

IMO, forget attempting to set RS flatslide carburetor floats with the (3mm below) clear tube method. 
It won't work because the RS carb float system is designed differently than BS34 CV carbs, for example.
I have personally owned three different RS series carb sets, and the 17mm +/- measurement method typically produced clear tube measurements around 4-5mm ABOVE the float bowl tops.

Site search result for daveo RS carbs way back yonder in 2017:

 

Not such a good pic, but this is on the bench at 23 mm, fuel level is now consistent across all 4 carbs, its lower than before and number 2 carb has stopped dribbling, i would sometimes see fuel dropping onto the floor, particulary if using the side stand, Hopefully this is the fix.

More old information:

www.kzrider.com/forum/3-carburetor/60229...eeded-please?start=0

😃

Float height and fuel level in float bowls can be two different things.

   Floats with metal frames can introduce all manner of inaccuracies due to the possibility of frames being tweaked asymmetrically (or otherwise) relative to each other and, the float needle tang.  Float bulbs are relatively far from their pivot point compared to the tang.  This equates to a long lever that affects distance traveled by the tang relative to the distance traveled by the bulb(s).  Tiny inaccuracies of the physical position(s) of the bulb(s) at rest height result in unpredictable inaccuracies at the tang.  If one bulb is not symmetrical to the other in every respect, float height(s) becomes inaccurate relative to the tang and fuel level.

   There's a poorly-documented spec for VM 28SC carbs in Mama Kaw's Z1 White Manual wherein the fuel level is stated to be 32mm +/- 1mm in Table 3 Carburetor Specifications.  In the same section (Maintenance) the clear tube spec is "... about 1/8 inch, or 2.4 ~ 4.5mm ..." below the edge of the carb body.  The discrepancy makes no sense until one realizes that the 32mm fuel level spec is the distance from the carb bore centerline to the fuel level in the float bowl.  This is hinted at in drawing 273 Fuel Level Measurement, but never clearly stated in the text.  We've confirmed this with very careful caliper measurements of the distance from the bore centerline to 3mm below the carb body at the float bowl of VM28 SC carbs.

  In other words, fuel level is somewhat independent of (possibly-inaccurate) float height.  Float height might get things in the ballpark, but cannot be trusted to be +/- 1mm of specified fuel level.

   Perusing the available documentation of the RS series carbs unfortunately shows no spec for fuel level below the bore centerline.  We'd go with clear tube results for fuel level adjustments.

   Non-adjustable all-plastic floats are another matter.  Best to replace them with OEM floats & needles of fuel level is suspect.

Good Ridin'
slmjim & Z1BEBE

Some Good / Interesting Info, obviously an issue thats been around for a while with the RS carbs. My floats  set at 23 mm has dropped fuel level lower than as found and has stopped one carb leaking during the bench test.

Ill try them as they are now set, my concern is if i will have sufficient fuel at higher RPM, im using a stock fuel tap.To get the level in pics took a lot of float tang adjustment, accelerator pumps were all still working correctly at this level.

Likely to be next year before testing as we are getting snow here this morning, soon be time to put the bike on the bench for winter work, 

slmjim+Z1BEBE wrote:

The discrepancy makes no sense until one realizes that the 32mm fuel level spec is the distance from the carb bore centerline to the fuel level in the float bowl.  

Perusing the available documentation of the RS series carbs unfortunately shows no spec for fuel level below the bore centerline. 

Good Ridin'
slmjim & Z1BEBE

The 32mm measurement noted falls in-line with the fuel level being 4mm+/- above the bowl top when utilizing the clear-tube method, with floats set at 17mm per the Mikuni RS manual instructions:

I check float hight measurents while carbs are apart. After they are assembled and ready to go on the bike. I do a clear tube check. About 50% of the time, I don't have to remove the bowls and re-adjust.

daveo wrote:

slmjim+Z1BEBE wrote:

The discrepancy makes no sense until one realizes that the 32mm fuel level spec is the distance from the carb bore centerline to the fuel level in the float bowl.  

Perusing the available documentation of the RS series carbs unfortunately shows no spec for fuel level below the bore centerline. 

Good Ridin'
slmjim & Z1BEBE

The 32mm measurement noted falls in-line with the fuel level being 4mm+/- above the bowl top when utilizing the clear-tube method, with floats set at 17mm per the Mikuni RS manual instructions:

 

   That 32mm fuel level is spec'd in the Z1 White Manual specifically for VM 28SC carbs.  We don't know, nor have we found,  a fuel level spec for distance in mm below the carb bore centerline of RS carbs.  If remembering correctly, there is a (clear tube) spec for distance relative to the bowl mating surface.  Don't assume the 32mm spec in the White Manual is accurate for RS carbs.

Good Ridin'
slmjim & Z1BEBE

Works for me...



Yet, the mystique surrounding proper float adjustment has not been fully resolved.

🤔

Well, it's only beet 40 years, whaddaya want??