Carb Float Adjustment Problems. Standard Dry Adjustment Results in Low Fuel Level

[Bob K.]

I'm trying to adjust the floats on my '93 Royale and I'm running into problems.

 

I adjusted my floats dry on the bench using this procedure (see pic). Float not compressing the float valve spring. Gap measured on the right side of the float as pictured. I set them all to 28.5mm clearance.

 

I created a wet test setup to test the carbs. I leveled each carb independently before measuring. I let the carb fill with fuel and then drained a little off through the drain valve to ensure the float was working properly. I also tapped the carbs and drain line to ensure there were no bubbles. Then I drained the test line and positioned it directly beside the diaphragm cover and held it firmly in place. I opened the fuel drain screw, let the tube fill, tapped the tube a couple times, and made a mark at the bottom of the meniscus.

 

I measured with calipers from the fuel level mark to the piston valve center mark.

 

Even after testing each carb twice, this 28.5mm dry float setting left me with high gaps (low fuel heights) of 21.3mm, 18.6mm, 17.7mm, and 18.1mm. The manual says 15.5mm to 16.5mm is correct.

 

I split the carbs apart and started to adjust the float height on carb #1 (the 21.3mm gap). After adjusting and wet testing carb #1 twice, I'm running out of tang adjustment. The setting pictured here still only gives me a 17.2mm gap. When I do push down on the float, the float contacts the jet block before the float needle spring is completely compressed. (I can only compress the spring about halfway in this current setting.) I think the tang would almost be touching the float body or the float would contact the jet block before I could get it adjusted to the point that it would give me a 15.5mm fuel gap. See this pic:

 

The bike has 40K miles on it, and the float and float valve appear to be in good shape. The carbs have been thoroughly scrubbed and the float valve orifices are clean. I'm the second owner. Do these look like standard parts?

 

If the float valve were failing, I would expect it to let in more fuel than desired rather than less. Also, if the float were losing its buoyancy, I'd expect to get more fuel than desired, not less. It's as if I have a super buoyant float that wants to close the float valve much sooner than desired, and I'm running out of adjustment on the tang to stop the valve from closing so soon. Or, the float valve is too long and is closing too soon, despite having adjusted the tang down as far as possible.

 

What do you suggest I do next to get this float adjusted properly?

Edited August 24, 2018 by Bob K.

[KISA]

Fuel level in the float-operated camera should be checked on the working motorcycle!

At the working motor level goes down on 1 mm!

[Patch]

1st question, are these pics from the set you are working on?

 

Are the float needle valves new? If so compare to the old ones.

 

Now I have seen this before including the float jamming.

 

Answer those and we'll take it from there

 

Patch

[Patch]

By the way, nice job cleaning the shells!

[Patch]

Ok I just checked what turns out to be your other thread.

 

Take a very close study of the pics that prairiehammer posted and compare the tab bracket to the ones you posted.

 

These must be perfectly flat and those shown are not!

 

You need to be careful as you try to correct them or they'll come apart and you need to replace them.

 

Insert a hardened pin into the pivot lay the float body on a smooth flat surface and apply pressure to flatten I think ones up and ones down so flip the float accordingly.

 

I adjust the tab with a flat driver in between the tab and body which applies pressure to both sides of the clip. If you just bend with pliers then you rick doing what has happened

 

You can pinch with long nose pliers to drop the height but I don't I rest the back on the bench for support usually

Edited August 24, 2018 by Patch

[Bob K.]

1st question, are these pics from the set you are working on?

Except for the first pic showing the dry float measuring technique, yes, these are my carbs.

 

Are the float needle valves new? If so compare to the old ones.

No, not during my ownership (since 2001). When I massage the float valve rubber tips, they're still pointed and flexible. They also close off nicely after the carbs fill. No leaking or overflowing.

 

The problem seems to be that I can't get enough fuel into the carbs before I run out of tang adjustment or float movement before the float contacts the jet block. Marcarl indicated in another float adjustment thread that he was never able to get a good wet measurement on the bench--that they always seemed to read low. Yet some folks seem to have no problem with a wet bench test.

[Patch]

Except for the first pic showing the dry float measuring technique, yes, these are my carbs.

 

 

No, not during my ownership (since 2001). When I massage the float valve rubber tips, they're still pointed and flexible. They also close off nicely after the carbs fill. No leaking or overflowing.

 

The problem seems to be that I can't get enough fuel into the carbs before I run out of tang adjustment or float movement before the float contacts the jet block. Marcarl indicated in another float adjustment thread that he was never able to get a good wet measurement on the bench--that they always seemed to read low. Yet some folks seem to have no problem with a wet bench test.

 

Bob it doesn't matter who or when/ you are in there for a reason and we see that the bracket is bent. That is the answer as far as I can tell form here..

[Bob K.]

@Steven G., I think this is what you're suggesting:

 

To be sure we have the same names for the same parts, here's what I'm using.

 

Are you recommending that the rounded portion of the tang wrap more around the circumference of the mounting pin inside the carb, such as by pushing in at the crease between the rounded portion of the tang and the flat portion of the tang? Also, are you recommending that the tang always be parallel with the tang bracket after the tang is adjusted?

Edited August 24, 2018 by Bob K.

[Bob K.]

I took a new approach based on the fact that the carbs are supposed to be wet checked while they're on a running motorcycle. A running motorcycle produces a lot of vibration. Without changing any of the dry float settings away from the recommended 28.5mm, I hooked up the test set, opened the fuel drain screw, and then tapped on the carb with a screwdriver handle for about 1 minute. Sure enough, the fuel level in the clear hose rose up substantially and then settled to a consistent level despite continued tapping. By dry setting the carbs at 28.5mm, the wet fuel level ended up being: 1--15.75mm, 2--16.25mm, 3--15.75mm, 4--16.0mm. With these settings, all of the float tangs are in reasonable positions, completely close the float valve spring, and the floats don't contact the jet block.

 

As the picture above indicates, the 28.5mm setting produces a float height on my carbs where the casting circle is just visible beneath the float. Also, my floats were originally set quite a bit richer (only about half the casting circle visible).

 

So...tap on those carbs and produce some vibration if you wet bench test them! I also recommend bench testing each carb independently before screwing them all back together. I made a lot of extra work for myself by first reassembling all four together and then needing to disconnect all of them to adjust the floats. Bonehead move.

Edited August 30, 2018 by Bob K.

[Patch]

Sorry Bob I responded on my way out to a wedding and perhaps didn't give the question you asked prior to, enough consideration!

 

Well I see you got things sorted, it looked like a bit of a challenge with the bent bracket tabs..

 

Just so you know the recommended float setting is base on the overall rpm range for possible fuel consumption at WOT a mm here or there no biggy unless your on a racer..

 

Patch

[Prairiehammer]

I took a new approach based on the fact that the carbs are supposed to be wet checked while they're on a running motorcycle. A running motorcycle produces a lot of vibration.

So...tap on those carbs and produce some vibration if you wet bench test them!

 

I think that is what the Russian @KISA was trying to tell us with his reply:

"Fuel level in the float-operated camera should be checked on the working motorcycle!

At the working motor level goes down on 1 mm! "