Float Height versus Fuel Level Height

[sbbloom69]

Hi, I've been off the site for a while. I've had my CBX since 1984 (2nd owner). I've been in and out if ICOA since then. I've had the carbs off about 6 times since then, various cleanings and a rebuild. I've never separated the carbs. I've always been successful leaving them assembled. Ive been tenacious about the jet/passage cleaning, with good success. This has worked for me. I also have a KZ1300 six with the three 2-barreled carbs (they're a PITA too).

I've developed a small leak. I first thought it was a finicky #2 carb float valve/needle. The leak seems to be worse after the bike has set a few weeks. It goes "almost" away after about 10 miles of driving. I drove the bike this way all last summer. Most of the time, it stopped. It's worse now. I've decided that I don't want to burn up this summer, so I'm going to pull the carbs for the 7th time in 32 years.

My overflow hoses cracked and broke years ago, so I never replaced them (so an overflow drips gas onto the crankcase). I do still have the drain hoses connected.

I have a slow drip right under #2 or maybe between #1 and #2. I'm not sure its the joint tube orings (original, never changed), maybe a sticky or cruddy float valve/needle with overflow, or a cracked overflow tube. The fact that it "gets better" after driving is leading me to the float valve or the joint pipe oring and not the tube. I've searched and read many posts here about the status and effects of ethanol fuel on nitrile/BUNA versus Viton orings.

I'll obviously find out when I pull the carbs which problem I have. The last rebuild kit I installed was in 2009 (thanks to Vince Ciotti who convinced me to finish my resurrection, the bike had been down for 7 years). I'd rather not overdo the carb work because the bike is running GREAT (I built a 6-cylinder carb sync tool for both the CBX and the KZ1300). My CBX is not real pretty anymore, but it sure runs good, except for this pesky leak.

I have several questions:
1. Can I buy or obtain just the joint o-rings (sizes?)
2. Can I buy just the float needles/seats?
3. Do I have to buy a whole set of kits ( the kits I've seen on line don't appear to have the float needles/seats anymore).
4. Should I just do it right and do an entire rebuild?

Finally, the main question: My KZ1300 has no spec for float height. The service manual and tech sights all say to use fuel level with a clear hose as the only reliable method for float/fuel height. I did this with my KZ and there was a noticeable difference between equal float height and where the fuel level via the tygon clear hose came out. I set the floats for equal fuel level. The KZ runs great and synced up easily.

Is there a specified "fuel level" using clear hose via the bowl drain nipple? I read one thread that had pictures, but the desired fuel level was "near the top of the back mounting plate screw". Is that the best guidance there is? In my opinion actual fuel level is a better indicator of what the carbs are doing.

Thanks in advance for answers. I'm not scared of the carbs, I've had them off 6 times before. I just don't like it. I really need to solve the fuel leak (who knows, maybe it will be just a sticky float valve or a split overflow tube). But it will also give me the excuse to pull my Bassani 6-2-1 header off and give it a new coat of black ceramic.

Stu
Los Alamos, NM

[sbbloom69]

Oh, I read here that a "temporary" fix may be to flood the carbs with Berryman's or some other solvent/chemical to swell the orings. Anyone else tried that? I know I'll do the carbs, I just have to figure out what parts to get and when I'm going to get the time to do it.

Stu

[steve murdoch icoa #5322]

I think a copy of the Mike Nixon carb cleaning book and a restoration kit from Randakk's would be your best bet.
The kit has all the rubber washers, plugs and gaskets required and they are viton.
http://randakks.com/products/randakks-o ... erhaul-kit

Hopefully the float seats and valves can be saved with a good cleaning/polishing.

[Larry Zimmer]

Sounds exactly like orings on the fuel transfer tubes between carbs. Will only get worse with time. (Ask me how I know!) Only certain fix is break the carbs and install new rings. I, finally, bit that bullet 2 years ago on my '82. Good to go ever since.

[herdygerdy]

+1 on Mike Nixon's book and the overhaul kit from Randall Washington, everything you need and nothing you don't..

Hell, you've had the old gal for 32 happy years, so it's time to return a bit of the love she has shown you. Do it once and do it right I say. And from the sounds of the experience you have, once done well, you will probably never need to go in there again. You are going to take them off anyway, so may as well do it so you can put them back on with confidence knowing they are as good as you can make them.

Also, check the brass overflow tubes in the float bowls for splitting along the length as well. Seen a couple of those in my day...

And worth pulling the pressed in idle jets to ensure the passages below are squeaky clean, ditto being able to check the accelerator pump jets for correct operation.

I have always taken the time to carefully set the float height to as close to 15.5 mm as I can get it. I tilt the carb on its side so the weight of the float does not press down on the needle valve and give a false reading.

A Q tip dipped in Brasso metal polish and spun by hand, (NOT a drill) is a good way to clean up the float needle sets also. That, along with Randall's kit with every O ring made of Viton and you will be rewarded with many more miles of smiles!

My two South Pacific pesos. Enjoy the journey - think of it as a man's meditation.

Cheers...Tony