Float Level?

[JKoepsell]

I just recently rebuilt my bottom end and decided to set float a bit leaner since it had been fouling plugs every once in a while. I checked the manual and it said stock setting was 9.5mm. I took off the float bowl and checked and the level was around 4mm. I do not think the owner before me ever touched it and I am sure I havn't either. I bent the tang A LOT to get it to 9.5mm and it seemed too much but I thought I would give it a try. My bike wouldn't even start. I checked the float bowl and there wasn't a drop of gas in there.... SO.... This is how I was measuring the float... Turn the carb upside down so that the float valve is completly closed but the pin is not being compressed at all. Then measure the highest point of the float to "gasket surface".... Does anyone know what I was doing wrong?
-Jimmy

 

[mandark1967]

http://justkdx.dirtrider.net/floatlevel.html

GREAT article on floats :)

 

[rmc_olderthandirt]

Then measure the highest point of the float to "gasket surface

Okay, you are holding the carb upside down so reference points might be inverted here: In this position the "highest point" would now be what is normally the bottom of the float. Or are you measuring the gap between the float and the gasket surface?

I don't know your bike so I don't know which is correct. On my YZ-125 the measurement is from what is normally the bottom of the float. I would say that to more than double what it was (4mm to 9.5) would be a MAJOR change so something was wrong.

I also would recommend that you NOT adjust the float level to make mixture adjustments.

Rod

 

[2strokerfun]

I also would recommend that you NOT adjust the float level to make mixture adjustments.

Generally, I agree with that statement. But, if the float level is off as much as he thought it was, I would also try and correct it.

I think I'd take it apart and try again. I've always wondered how float level changes without someone bending them. Anyone know ??

 

[Reesknight]

I'm no expert, but I think the float measurement is from the time the valve closes, to the float bowl gasket surface. It will usually settle down lower(upside down) than where the valve actually closes. If you bent your tab to where is actually sits higher, (again upside down) then you have cut the fuel flow to nothing. You may be able to cut a piece of line so you can blow into the carb where the fuel would enter, to be able to listen to where the float valve stops the flow, or maybe you can tell where it closes by feeling a slight notch.
Then again, I may be way off. :coocoo:

It was probably set right to begin with, but maybe the needle was worn.

 

[JKoepsell]

I measured it by the distance (carb being upside down) between the "gasket surface" and the highest point on the float.... Another way I tested it to make sure I was measuring the right distance was to attach the fuel line. I would leave the bowl off and keep the gas on.... Then I would lower the float by hand 'till I found the sweet spot between gas and no gas. I measured the bottom of the float (it being right-side up now) to the "gasket surface".

2Strokerfun - The tang which you bend is part of the float, when the fuel level rises, so does the float and tang. The tang is what the float valve rests upon and as the fuel rises it blocks off the hole the gas runs through, just like the toilet example. When you bend the tang upwards with the float right side up, it forces the valve to shut earlier...

I am going to try again, maybe I made some stupid mistake or something... it happens a lot unfortunatly :coocoo: :)

 

[rmc_olderthandirt]

The adjustment is via a fairly flexible tab of metal. It is possible that if the bike was shook really good the banging around of the float in the bowl could cause the tab to get bent. I would think that the only direction it could change would be to have the float level raise, however.

When you clean the carburetor, and especially when you replace the needle valve or the gasket under the valve then all bets are off. A variation in the gasket thickness or even how tight you wrenched the valve down will change the float height.

Rod