Carb float range

[AdamX]

Working on my 77 standard. Noticed fuel in the drain hoses. Looked at the heights and they checked out to 24mm. Thought about raising them. With the bowls off, I inverted the carbs. At this point I noticed that one float lowered so much that the float needle almosts comes out. Flipping upside down reveals the carb float and needle sticking into place. The other carb does not do this. The errant float seems to have more travel than the other. I swapped floats with the good carb and determined that the posts on that carb might be worn down. Anyone have to deal with this or have any advice on how to reduce the travel? I've attached pic of what the float is doing.

 

[xjwmx]

I think the farther it comes out, the more likely it is to hang, and it doesn't need to come out unnecessarily far. Remember the floats will be bouncing like crazy and the fuel level is sort of an average. So. The BS34 solid plastic floats have a tang that can be bent to control how far they fall. Look for something like that on yours. One possibility with a float that has limited movement and uses a rubber tip needle is the tip is swollen; had that happen w/ an aftermarket replacement. Never again.

 

[nj1639]

http://www.amckayltd.com/carbguide.pdf

Here ya go. '77 Standard should have the bs38 aluminum top, brass float carbs.

 

[AdamX]

it does have tang that allows you to set the float height. I have that set at 24mm from the base to the top of the float as described in the manual. I havent mic'd them yet but I think the posts are worn compared to the other carb. I think this is allowing more travel away from the float needle causing enough clearance for the needle to jam it up.

 

[TwoManyXS1Bs]

... The BS34 solid plastic floats have a tang that can be bent to control how far they fall. Look for something like that on yours...

BS34 float 'stop' tang.

Haven't seen any 'stop' tangs on BS38 floats.

I suppose you could add a little dollip of solder to a brass float arm, to act as a stop tang...

 

[AdamX]

Right. Mine does not have that

 

[xjwmx]

I suppose you could add a little dollip of solder to a brass float arm, to act as a stop tang...

If the problem is a notch worn in the post that the arm goes into, letting it fall too far, you might be able to put a thin sleeve of something over the post. Possibly wrap the post with thin wire, like stripped electronic "wire-wrapping" wire or thin bell wire with the enamel sanded off and hold it in place by soldering it to itself. Never heard of this problem before but I'm the least expert on BS38 carbs here probably ...

 

[5twins]

The float can't fall too much once the bowl is in place, it will stop it. Also, since there will be some fuel at least in there, it won't sink to the bottom of the bowl anyway.

The level spec for the '76-'77 carbs is 25mm. That would give a slightly lower fuel level in the bowl than the 24mm setting you have now. You might try that and maybe it will stop the dribbling. You didn't mention doing so but when you set floats, you should measure both sides of each float. The float "bulbs" are often twisted or tweaked on the mounting bracket. One will be sitting higher or lower than the other. You won't catch that unless you check both sides.

 

[5twins]

Also, maybe it's just the angle of your photo, but your float tang looks bent way too much. Properly set, the tang should be pretty much even with and parallel to the rest of the mounting bracket .....

 

[AdamX]

I think you nailed it 5twins. A co-worker of mine mentioned the same thing about the bowls. Just tried it out and, sure enough, you both are correct. (face buried in hand right now). I'll raise to 25mm (both bulbs) and reinstall to the bike.
Thanks Everyone!
-Adam

 

[AdamX]

Just an update to this thread. Had raised the floats to 25mm at that time (Jan 8th). Ran a test ride around the neighborhood. Still had some gas in the drains. Suppose that is from sloshing around? I'd estimate about 4 tablespoons.