Clear Tubes for checking float level

[cfairweather]

A great way to verify the float level and float valves is to connect four clear tubes to each drain hole. If you buy these tubes on EBay, they will cost you about $20.00 each so most people cannot justify buying them. Good news, you can make your own. Order some inexpensive M6 X .75mm zerk grease fittings and drill out the spring. The ball will easily come out once you remove the spring. Then drill out the hole with a 1/16" bit. Here is a picture of the set I recently made.

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[Barrie]

Nice solution!

[MattMcCoy]

My understanding is that you would point the opposite end of the tubing up and above the float to verify the level of fuel in the bowl — correct?

[Lucien Harpress]

This technique is the only way to measure the fuel level in my KZ1300. Best way I read to do it is to route your clear lines back up above your float bowls, then hook up your IV fuel tank to the carb rack.

The trick is that once the fuel level stabilizes, pull the upturned loop of the clear lines down, slowly. Be SURE to only go down- pulling them back up will screw up your reading. But going down allows the extra fuel to be pulled in from your IV tank, any kind of funky air bubbles be pulled clear of your drain line, and fluid dynamics being what they are the level in the clear tube remains identical to that in the bowl.

I scratched a small line on the outside of my carb bowls at the correct fuel level, just to eliminate the need to mess with a ruler.

[cfairweather]

Yes, the open end must remain up above the carb or fuel will run out. Put your GL1000 on the center stand if the carbs are on the motorcycle so it will be level. You place the tube next to the float bowl outer edge, the rim edge that is closest to the chrome brackets and this is the lowest part of the carb. The gasoline in the bowl should rise no higher than the top edge and ideally should be at the lower edge. If the level rises way above the top edge, you probably have a leaky float valve and you may see gas flow into the plenum. If you have a level higher than the top edge or more than about 1/8" below the bottom edge, you need to adjust the float level. I always check carbs using an electric fuel pump to test the float valves and I view the levels with these tubes. I think it is the best way to know what the floats are doing. You can also use these to troubleshoot carbs while they are still installed on the motorcycle. You obviously need to be careful if you choose to use these while the motorcycle is running because there is a chance you could leak gas and have a fire. Do this at your own risk and I hope this helps explain how to use these.

[gltriker]

This technique is the only way to measure the fuel level in my KZ1300. Best way I read to do it is to route your clear lines back up above your float bowls, then hook up your IV fuel tank to the carb rack.

The trick is that once the fuel level stabilizes, pull the upturned loop of the clear lines down, slowly. Be SURE to only go down- pulling them back up will screw up your reading. But going down allows the extra fuel to be pulled in from your IV tank, any kind of funky air bubbles be pulled clear of your drain line, and fluid dynamics being what they are the level in the clear tube remains identical to that in the bowl.

I scratched a small line on the outside of my carb bowls at the correct fuel level, just to eliminate the need to mess with a ruler.

What? Drain lines up and down. Funky air bubbles in your drain line. Clear lines. Clear tube.
This is what you have to contend with on a KZ1300? Whew.

[redglbx]

Cfairweather, great tip ! I would like to ask if you could post a picture or 2 to define the hi/low levels that you’re talking about to make this a perfect lesson/tip for future questions & tips. Thx !

[Lucien Harpress]

What? Drain lines up and down. Funky air bubbles in your drain line. Clear lines. Clear tube.
This is what you have to contend with on a KZ1300? Whew.

Yup. If you want to get SUPER-technical, it's actually a more accurate way of checking bowl level, because you're measuring what you want directly, not indirectly like with a simple float height setting. It eliminates variables like floats that float slightly higher or lower than others, depending on age, fuel saturation, etc.

In practice? I've noticed floats either tend to work or they don't, without much in-between. And neither method is worth a darn if you don't have the value it's supposed to be set to anyway.....

[PDub]

Any reason you couldn't do this on the bench following a carb rebuild?

[cfairweather]

I always check the carbs with tubes after I rebuild them. I use an electric fuel pump.

[Lucien Harpress]

On the bench is probably the best way to test them. That way you can get level out the carbs and get a "true" reading.

Checking in on the bike is still helpful, but all it's going to tell you is if your float valves are leaking or not, NOT if they are set at the correct height. Like I said though, I'm not aware of any information about what the actual fuel level is supposed to BE, so I probably wouldn't use it to set float height.

[cfairweather]

Lucien is correct. The Honda method of setting the floats doesn't include the clear tube method, but my experience has taught me that the optimal level is the lower edge of the rim. And the side of the carb I am referring to is closest to the chrome bracket. This is the lowest edge because the carbs are mounted at a slight angle. As long as the level is not higher than the top edge of the rim, you won't have a problem, but I always set mine to the lower edge or slightly over the lower edge. If you rebuild a set, carefully adjust the floats according to the Honda specifications. Then use an electric fuel pump and clear tubes to check the level. Let's say three are just above the lower edge and one is at the top edge. It would make sense for you to fine tune the one that is high.

[Sidecar Bob]

This method is well known on cx500forum.com (& easier there because the float bowls have overflow/drain hose barbs so all you have to do is connect the hoses, tie their ends higher than the float bowl and open the drain screw). If you know what the level is supposed to be it is a simple way to find out if the bowls are over or under filling without having to remove them from the bike (thus saving time & effort that could be put into looking for other problems if the levels are OK).

For CX/GL500/650 carbs the level should be about 2mm below the float bowl gasket (just about even with the bottom of the bowl's flange) and I expect GW carbs will be about the same. This info can be attained by a few people carefully checking their float heights, checking them with the clear hoses and letting the rest of us know the level so it can become community lore.

[cfairweather]

As requested, here are some pictures of viewing the actual level of correctly set floats. You can see the level is between the lower lip edge and the upper lip edge. I prefer getting the level near the lower edge. The last picture shows a level next to a float bowl so you can see where the level would be if the level is near the lower edge. In this picture, the carb set is on a flat level surface and so is the level.

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DSCN3813.JPG (181.4 KiB) Viewed 802 times

DSCN3820.JPG (141.41 KiB) Viewed 802 times

[gltriker]

cfairweather
Were your carburetors ultrasonically cleaned?