Carb Float Level

[grumpy56]

Trying to adjust the float level on a set of Mikuni VM32SH carbs. The level from the top of the float to the needle (I assume just when touching it) is supposed to be 27.5 mm. However, when I set it at this height, the floats have to touch the body of the carb for the valve to seat and seal the orifice. That doesn't sound right to me, but wanted to get some expert advice. One of the carbs was overflowing so it was not closing that valve for sure. Thoughts? Thanks.

Float 1.JPG

Float 2.JPG

[rngdng]

On thing that's wrong is you have a gasket in place. Float height must be done from the gasket sealing surface WITHOUT a gasket. It may be that your floats have been bent in relation to the "tang". The tang should be nearly flat when everything is correct. Are the floats right-side up?



Lane

[grumpy56]

Hey Lane. Will remove that gasket when I check it again, but that is only going to make the float even higher in the bowl. I also am not certain what is "right side up" with the float, but if I turn it around, it is too low for the bowel to attach.

[rngdng]

You are right or course, that is why I'm wondering if the floats got bent at the mounting points. I know the likelihood of them both being bent wrong, in the same way, is pretty slim. But, something has gotta give here. Good luck, and keep us posted.


Lane

[Vintageman]

I can tell by the picture (shinny metal gasket not the reddish OEM one) you may be using an aftermarket float needle valve assembly. My guess/experience if you would compare the height of this aftermarket ones body to the stock one you took out it is shorter. Options is to add one or two OEM gasket to raise it back up.

I am of the position to try only changing float needles next time when I am (most of the time) too cheep to buy OEM float valve.

Somewhere online there is a chart of float needle dimension.. can't find it now

here is an example og a replacement needle
http://www.ebay.com/itm/72-77-SUZUKI-GT ... DT&vxp=mtr" onclick="window.open(this.href);return false;

Here is another idea
https://www.youtube.com/watch?v=zlez_hdoWYk" onclick="window.open(this.href);return false;

[locobuilderbri]

Trying to adjust the float level on a set of Mikuni VM32SH carbs. The level from the top of the float to the needle (I assume just when touching it) is supposed to be 27.5 mm. However, when I set it at this height, the floats have to touch the body of the carb for the valve to seat and seal the orifice. That doesn't sound right to me, but wanted to get some expert advice. One of the carbs was overflowing so it was not closing that valve for sure. Thoughts? Thanks.

Float 1.JPG

Float 2.JPG

You dont say what bike these carbs are fitted to, But would i be correct in assuming a T350R,J ?
If so you are measuring the float height from the wrong place! The distance should be measured from the top of the
float arm to the main jet fitting seat.
Have look at Suzuki Service Data Manual page 7 on http://www.ozebook.com" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;"
The drawing on the bottom r/h side labelled Type B shows the correct way to measure the float height for a T350R,J
Ignore all that "onclick----etcfalse;" dont know what thats all about but i cant get rid of it!

[grumpy56]

It is a 1970 T350II. Attached is a pic from my service manual. It shows the measurement from the top (or bottom) of the float.

Float level.JPG

[tz375]

Just as a point of reference, that picture in the FSM is wrong. The measurement may be correct but the carb should not be upside down. Upside down, the float will usually compress the small spring inside the float valve.

The correct way is like your first picture. tilt the crab until the tang on the float just touches the spring loaded plunger and set that height

[grumpy56]

Thanks MotoGP. I am measuring it just as the tang hits the spring.

[Vintageman]

grumpy56,

was my reply not helpful?


Maybe I don't understand the issue

[grumpy56]

Hey Vintageman. Have not yet attached the carbs and tried them again, but re-assembled them with the old valves after cleaning them per a video that was suggested. The valve assemblies are different in height, not by much, but abut a mm. Appreciate all the help.

[tz375]

Now I am confused. If I understand your original question and teh replies, you are setting the float height at 27.5 as the tang just rests on the needle valve plunger and the valves are not closing. That doesn't sound right. Your original question said you measured from the float to the needle valve but that isn't what the picture from the FSM shows, so I'm not sure exactly what you are measuring.

[Vintageman]

1mm is a lot when it near the fulcrum point.

Check the old float needle and see if the tip is damaged or indented (ring like). it alone can be replaced as noted in my first reply.

[locobuilderbri]

It is a 1970 T350II. Attached is a pic from my service manual. It shows the measurement from the top (or bottom) of the float.

Float level.JPG

Check out http;//www.oldjapanesebikes.com/mraxl_GT_resou ... /index.php
Pages 6 & 7 Your model & year bike are listed as having mikuni carbs marked 18630 which have the float height set by a different method to that shown in most manual. I set my carb float heights by this method on my T250j when i also had overflowing carbs.

[tz375]

1mm is a lot when it near the fulcrum point.

That's the point. No one should ever be measuring float levels near the pivot.