Topic: Float bowl fuel level

[Donzon]

  Being faced with the task of checking the fuel levels in my float bowls ( CB750K4)  and being in too much of a hurry to manufacture one of the fancy, nifty rigs mentioned here, I stumbled onto what seems to be the cheapest and easiest solution possible.  All you need is a couple feet of 1/4 inch outside diameter PVC or Vinyl tubing, the stuff used for airline, water line etc. PVC works better as it's stiffer.  Mine is airline, but I've seen similar stuff at Home Depot and other places.  The thick wall stuff works best as you are going to be stretching it and you need some meat to work with.

  Take your piece of  tubing , clamp one end, move over about 6 inches and slowly heat a section about one inch long till it softens and you can stretch it.  A heat gun works best, but I know not everyone has one so I tried it with a lighter and it works fine, just try to heat the tube evenly or it won't form up as nicely.  Stretch the heated section until it narrows somewhat and let it cool off for a few seconds.  Now you can cut in the center of the stretched section and you will have two tapered ends.  Cut the tubes to a convenient size, mine were about 5 inches long.  Repeat the process and you now have 4 short tubes with a tapered end.

  Remove your float bowl drain screws and try the tapered ends of the tubes to see how far they will go into the drains.  Cut them so they will go in about 1/4 to 3/8 inch or so.  You now just screw them into the drain holes till they're tight and you're done.

  It doesn't get any easier than that.  No leakage and I even ran the engine with them in place! 


  Cheers
  Don

[mystic_1]

Nice hack, beats the hell out of drilling out some extra drain screws to make adapters.

10 points.

mystic_1

[martino1972]

very interesting,i'll try that..

[Bob Wessner]

I used similar tubes to check the levels on mine a couple of years ago. I used slightly smaller tube and fooled around wrapping some Teflon tape on the ends and 'screwing' that in. This is a much better and simpler approach. Definitely will try this next time.

[jreich]

Great idea...thanks for that Don!

[greenjeans]

The simplest things......
great tip !

[Deltarider]

That's science at it's best: simple and true.

[Mach5]

Where do you want the fluid level to be using this method?

[a.raia]

 I have a 1977 cb550f that I'm trying to get right, using your tube idea my fuel level is above the bowl at front of bike and between bowl and carb base (rear of bike) on all 4 carbs . help Tony

[Donzon]

You still should be setting the floats to the factory specs to begin with.  The idea of the tubes to determine if the floats are equal across the rack.  Sometimes a variation in the floats, or some other issue causes one float to sit lower than the others, or perhaps hang up in the bowl where you can't see it.  The tubes allow you to check for that sort of thing, in order to make the necessary adjustments.

Cheers
Don

[OakBehringer]

Awesome - I'll likely be doing this soon. Thanks.

BTW - Looks like you 750 owners have way more room around your carbs than us with 350s. So Nice for you.

[Sporkfly]

To make a comment on this technique:

I made a manometer from glass bottles and the same plastic tubing. Vacuum adapters for the carbs can be made using the same method, taper it on both ends so you can screw it into the adapter opening and fit the tubing over the other.

[Johnny5]

I have a CB350, and the floats are to be adjusted at 26mm. Now using the tube method here, would I measure 26mm from the bottom of the bowl and mark it on the outside? I guess, Im curious how do I find the measurement to match the fuel to from the outside.

Thanks,

[BobbyR]

That is a very clever solution. However, I just stick a piece of tubing over the drain at the bottom. It works the same. Fluid will seek it's own level.

[Bob Wessner]

That is a very clever solution. However, I just stick a piece of tubing over the drain at the bottom. It works the same. Fluid will seek it's own level.

On some models the 'drain' is separate from the overflow tube. On these, what protrudes from the bottom of the bowl is the overflow tube, so this won't work.. it would be too easy.

[BobbyR]

That is a very clever solution. However, I just stick a piece of tubing over the drain at the bottom. It works the same. Fluid will seek it's own level.

On some models the 'drain' is separate from the overflow tube. On these, what protrudes from the bottom of the bowl is the overflow tube, so this won't work.. it would be too easy.

Then again I am blessed having a 78K. See they got everything right. 

[Bob Wessner]

Ever the optimist, eh?

[BobbyR]

Ever the optimist, eh?

Yep 

[Don R]

It seems about 1/4" down on the bowl is correct for a 750F1. Like the photo.

[lucky]

Awesome - I'll likely be doing this soon. Thanks.

BTW - Looks like you 750 owners have way more room around your carbs than us with 350s. So Nice for you.

Never adjust float level on used float needles.
Put in new float needles and set floats to factory specs.
Then you will never need to adjust the floats again.
Just put in new needles every 2 years.

BTW...on1978 style floats all you need is a steel ruler.
when the ruler is set across the idle jet and the float is .570 thousandths above the carb body when the carb body is upside down this is what you will see.
Do not put any pressure on the float to make it line up. adjust the tang to make this happen.
You will see the light! Ding...ding ding!

[lucky]

I have a CB350, and the floats are to be adjusted at 26mm. Now using the tube method here, would I measure 26mm from the bottom of the bowl and mark it on the outside? I guess, Im curious how do I find the measurement to match the fuel to from the outside.

Thanks,

The Clymer's workshop manual tells you to measure them FIRST!

Then do the "clear tube method" if you want.

But remember ...the float level CANNOT be higher that the overflow tube inside the float bowl!!!

[Hon3ybadger]

[/quote]
But remember ...the float level CANNOT be higher that the overflow tube inside the float bowl!!!
[/quote]

That is the most basic rule to follow to avoid problems. It should be in bold!

[Holshot]

I think this is exactly what I was looking for! Thanks... bookmarked