Float valves
I like rebuilding carburetors for machines I am the most familiar with. That is, I know 70s and 80s street Hondas well and I like to think about these bikes as I do the carbs, knowing where their weak points are and how in some cases they can be overcome by paying special attention to the carburetors. You may think that approach is assumed, taken for granted. But I can tell you nearly all of the carb rebuilders out there are clueless about the bikes belonging to the carbs they work on. They know nothing about them. And an astonishing percentage of these folks know very little or nothing even about motorcycles in general. Years ago I had to convince one of them to leak test his rebuilt carburetors. Honda is the only one of the Big Four that still makes available vintage OEM float valves. If I can't get factory float valves, I won't rebuild the carbs. I won't make excuses. This is why I don't do older Kawasakis, or any Yamahas or Suzukis. There are no OEM float valves available for them. I don't want to make excuses to my customers. What a terrible thing to have to do.

Rebuilding carburetors
We've already explored the air bleeds which feed atmospheric air into the fuel circuits to make the fuel pre-atomize as it rises into the venturi. Thus every atomizing circuit in a Honda carburetor describes a "Y" shape, with fuel at the bottom of the "Y", air on a second branch, and fuel and air coming together on a third branch at the top. All three legs are critical when cleaning carburetors, but many overlook this. Ultrasonic is now the preferred cleaning method and that is a good thing considering the mess and hazards of traditional cleaning chemicals. Ultrasonic works well but only when the ultrasonic machine is high enough power. Ultrasonic cleaning does not replace hand vetting and cleaning however. That still needs to be done in addition to the ultrasonic. Each circuit, each passage, needs to be cleaned with cleaner aerosol and confirmed visually. Despite the opinions of some, wet blasting ("vapor honing") is not a substitute for carburetor cleaning. Blasting is not cleaning. It is a carb body exterior refinishing process, not an internal passage resin removal process.

Carburetor rebuild kits
Honda never sold rebuild kits for its production powersports carburetors. Instead, the company has traditionally supplied "packing sets". "Packing" is another word for gasket, thus in reality these were carburetor gasket sets. They included some sealing o-rings, but no diaphragms, float valves, metering parts or screws. Which is normal. You could buy all of these things individually from Honda, just not as part of the packing set. One of the most perverse things in this industry is how inundated it has become with aftermarket carburetor rebuild kits. These contain metering parts in addition to the gaskets. This is unfortunate. The most important parts of the carburetor, the parts with the most engineering and the most effect on the bulk of the carburetor's function, you're going to replace with cheaply-made junk? Even the kits carrying the most respected names ruin carburetors. Their jet needles and needle jets in some cases are so far off the factory dimensions that they permanently make the carburetors work badly. What do you think the chances are that a company who claims their part fits two or three different models will properly substitute for a part the factory has exerted its considerable resources to design to the extent that it puts a different jet needle into each year of a given model? I wouldn't take that bet.

These bad float valves are often found in rebuild kits. Certain forums have made an effort to compare different carburetor rebuild kits. I hope it instructs as instruction is badly needed. And I really appreciate the effort that goes into these articles. But why compare carb kits? Putting carb kits up for comparison is like having a farting contest. The problem is the subject is still a fart. There is nothing good about carb rebuild kits. For the life of me I cannot figure out the average consumer's fascination with them. Maybe it's the influence of the car repair trade. I dunno. But I know this--people within the industry have avoided them for seeming millennia, using instead quality rebuild parts from legitimate sources, including mostly Honda themselves. No reasonably competent carburetor rebuilder uses kits. They're extremely cheaply made, and more importantly, frequently result in that supreme tragedy, the ignorant tossing of perfectly good and very difficult to find OEM jet needles and needle jets. I deal with this issue almost weekly, having to inform my customers of the presence of Chinese or "high performance" metering parts in their carbs and the cost to replace them with OEM. The problem is OEM is pretty expensive because it's available only by buying whole carburetor assemblies. Cannibalizing, in other words. The jets in kits always off-size too, that is, not what they are marked, if they are marked, which sometimes they aren't even. The unavailability of carburetor "hard parts"--that is, mostly the metal parts, parts other than the widely-available gaskets, o-rings, screws, jets, and seals--is the real world of vintage Honda carburetor rebuilding. And it's why I don't rebuild even my favorite Honda carburetors, because they were made so long ago there are no jet needles, needle jets, or float valves for them fro Honda.

Part 8