BS32 Float Height

[jdub6092]

Putting my carbs back together and whether using original float seat and valve needle or K&L rebuild parts, the original floats need the tab bended by what seems to be an excessive amount. I am pretty sure they weren't like this when I tore them down. Does this look normal? This is what it takes to get the height of 22.4mm.

 

[Nessism]

That's totally wrong. The float tang should be very slightly angled down, not angled like that.

Are you sure you are measuring correctly? If the spring loaded tip in the float valve needle won't hold up the weight of the float, you need new float valves. Don't try to replace the needles, get new float valves. Mikuni brand are best. Keyster decent. K&L are junk.

 

[jdub6092]

That's totally wrong. The float tang should be very slightly angled down, not angled like that.

Are you sure you are measuring correctly? If the spring loaded tip in the float valve needle won't hold up the weight of the float, you need new float valves. Don't try to replace the needles, get new float valves. Mikuni brand are best. Keyster decent. K&L are junk.

It was the same for Mikuni and K&L (matched seats and needles) and I angled the carb until it was just touching the damper.
I was very hesitant to try bending the hinge upward as I haven't been able to find anyone doing it. It doesn't take much.
Gave it a shot and was able to get the tab back to almost level.


I wish I could have kept all original mikuni parts, but two of the needle dampers are nearly seized.

 

[jdub6092]

This is my measurement method. Pretty typical.

 

[Nessism]

Is the weight of the float compressing the needle spring?

And remember: float height is just to get you close, it's fuel level that really matters. You may have to make some clear tube adapters. It's easy to do.

 

[jdub6092]

Is the weight of the float compressing the needle spring?

Nope, I have it just making contact with the damper spring.

And remember: float height is just to get you close, it's fuel level that really matters. You may have to make some clear tube adapters. It's easy to do.

I do want to do that as well as a leak test. Don't want to R&R the carbs anymore. It's the most difficult and frustrating task I've done on this bike due to tight clearance.
You might be right about K&L. The float valve seat does not fit nearly as tight as the Mikuni.

I've seen the drilled out float bowl screw method for the adapter, but don't have a spare screw. If you'd like to share your method or a link, I'd very much appreciate it.

 

[Nessism]

Buy screws matching drain screw thread pitch. Drill hole through. Epoxy, JB Weld, small pieces of copper tubing into hole. Attach clear tube on copper tube to make tool.

 

[bwringer]

Buy screws matching drain screw thread pitch. Drill hole through. Epoxy, JB Weld, small pieces of copper tubing into hole. Attach clear tube on copper tube to make tool.

I've successfully used plain Tygon tubing many times. Select a hunk of translucent fuel tubing with an OD a little larger than the threads and just screw it into the float bowl. The soft plastic will catch the threads and seal surprisingly well.

If I had to guess, I've probably used 3/16" ID fuel tubing. The threads in the float bowls are a weird extra-fine M6 for some unknown reason. 6mm is a little smaller than 1/4".

 

[jdub6092]

I've successfully used plain Tygon tubing many times. Select a hunk of translucent fuel tubing with an OD a little larger than the threads and just screw it into the float bowl. The soft plastic will catch the threads and seal surprisingly well.

If I had to guess, I've probably used 3/16" ID fuel tubing. The threads in the float bowls are a weird extra-fine M6 for some unknown reason. 6mm is a little smaller than 1/4".

I'm trying to picture this in my head.
Are you screwing the tube into the threads from inside the bowl and then taking the screw out and that would keep the tube sealed?

 

[Nessism]

If you have a bench grinder, pencil point the tube by grinding the end. Then, screw it into the drain screw threads, as tightly as possible. This is what I do with VM carbs. CV float bowls have a notch in the threads, so it may not seal perfectly. It's worth a try though.

 

[Burque73]

jdub6092 If you can't get the tube mentioned above to thread into the drain, another option is to look for some tubing large enough to clamp onto the outside of the drain.

 

[bwringer]

I'm trying to picture this in my head.
Are you screwing the tube into the threads from inside the bowl and then taking the screw out and that would keep the tube sealed?

No, from the outside of the bowl. Pretend the tubing is a bolt and try threading it in just like it's a bolt.

And that's a good point about the notch in the threads in some carbs, Ed. Last time I did this was on VM carbs, so it may not work on BS carbs.

If you can scare up a spare drain bolt and modify it, that's a sure-fire way to handle this.