Checking carb float height?

[Durt Cycler]

I wanna check my carb float height cause when I tilt my bike over some it gas starts to come out of my overflow but when straight up or tilted alittle over it doesn't flow out. I have a manual tho but I never checked the float height before on a carb so could someone give me steps on how to do so? Thanks for any help. DC

 

[Durt Cycler]

Anybody?:think

 

[biglou]

Here's a description from memory, so bear with me. Hopefully your manual has a picture, and also the correct distance and reference points for measuring the float height. Also keep in mind that fuel will leak out of the O/F when tilted regardless.

Turn off the fuel. Drain the carb. Take the carb off. Turn it upside down and remove the float bowl. With the carb upside down, the float will be resting on the float needle and the float needle is resting in its seat. This is where the float is when the bowl has enough fuel to "Float" it. The needle is forced into the seat, cutting off further fuel flow into the bowl. Your manual should have a dimension, say, 12mm. That is mesured from the deck surface where the float bowl was removed to a point on the float. Usually the centerline of the float. (You can usually see the centerline running arount the float where the two hollow halves were joined together. Kind of like a mold line). If you don't have a specific dimension called out in your book (although I'm sure it's there), a good rule of thumb is to level the float in relation to the deck on the carb body.

If this measurement is not correct, you will carefully bend the metal tab that connects the float bowl to the float needle. Asjust as necessary and you're done. Put her back together and fire it up!

A couple of notes: The pin that the float rotates on will sometimes fall out if you tilt the carb sideways with the bowl removed. Watch out for that. When that happens, stuff falls out all over the place and if you didn't see how it was put together, you might be in for some fun! When the bowl i sinstalled, that pin is "captured" and can't fall out. It also won't fall out if you keep the carb upsidedown.

 

[MikeT]

Good discription Lou.

 

[Danman]

What did you use to measure the distance with?

I'm cleaning my carb tonight and was going to check that. I have not looked at the Clymer yet, but I will be for I start. I had to clean out the bowl last weekend at the truck and blow a chuck of something out of the main jet. I noticed a lot of dirt in the bottom of the bowl. I used some gas out from the tank to flush it out, but I imagine the rest of the carb is dirty as well. So I will be giving it a good cleaning tonight.

P.S. If you have a pumper carb don't press the plunger on the side of the bowl. It fell out and I was examining which direction it went back in and I shoved it in with my thumb. I got a good squire from it, almost in the eye. Flushed eye with water from Camelbak. Almost dropped the bowl in the sand when it happend.

Any of you people run a in line filter to keep trash out of the carb?

 

[biglou]

Dan-I used a small machinist's scale, which is just a little metal ruler with pretty accurate markings. I would shy away from using a tape measure, as the "hook" on the end can skew the reading quite a bit. No biggie if you're measuring a plot of land, big biggie if you're measuring fractins of an inch!

You may have to do a conversion from english to metric. One inch = 25.4mm.
You can always do the "level" technique also. ie: just level the float relative to the bowl deck.

 

[Durt Cycler]

Thanks for the help BigLou :moon:

 

[geremacheks]

I seem to be in the same predicament with my carb on my 00 EXC 200. Carb was leaking straight and fast from the vent tube, and mucho tapping on the carb would not stop it. Dropped the bowl (carb is slanted and still on bike), everything looked fine and exceptionally clean, needle valve sharp and soft. And if you held the needle valve up with your finger, with gas on, it holds the gas back from flowing. I believe that means the needle valve works. At the time, had a friend handy who was carb- smart, put it all back together in a few minutes and then he had to leave. I later checked it for leaks and had the same problems.

So, as he says, something's rubbing on the float bowl, or I need the float adjusted. I bent the tap on the float a tiny bit on the next invasion of the float bowl. And yes the pin for the float fell out, but that was no problem--I actually figured that all out. I also added an in line filter.

Problem now is that I can't get the bowl back on over the floats to reinstall. I've tried my patience for more than three hours, off and on, trying not to force anything. But can't get it on. I've tried it with the floats up high, in the middle, and down low. I ruled out down low.

I know exactly how the bowl lines up to the bottom of the carb without the floats in. With a little leaning, and slight pushing, the bowl snaps in completely. But can't do it with the floats and needle valve in place. I get within 3/8's of an inch of completion, but then I don't want to force it.

Hopefully my friend will help me with this soon. But even so, I have strong feelings that the carb will leak straight thru the vent tube when I'm finished. I don't think I fixed anything yet. (Maybe even made it worse).

I've loosened the frame and counter sprocket guards, and there seems to be enough room to reinstall the bowl, so I prefer not to take the carb off the bike and don't think I need to, so far.

Any suggestions? And yes, I don't have great gearhead skills. What's making this thing suddenly leak? Hope some of this has helped DC

 

[biglou]

A couple of thoughts. I would pull the carb off completely to reassemble. You've probably done more work to avoid it so far than it would take to actually remove it!

You need to have the carb off the bike and be able to turn it upside down to be able to adjust it, especially if you are new to this (like me). You may only be able to "ballpark" it with the carb still on the bike. Plus you get a much better view of what's going on in there. You can get a good view of the needle and seat, also. There may be a piece of grit or something in the seat that is preventing a complete seal. Also, pushing it up with your finger you may be applying much more force than what the float applies to the needle and seat from its bouancy in the fuel bowl.

 

[geremacheks]

Thanks for your fast reply.

You're right. It's because I'm so unsure of myself as a mechanic that I would rather not take the carb off the bike. There's no rush to ride the bike at present, so I do think I'll wait for my friend to look at it. Then he'll probably suggest the same thing.

The seat looked clean--checked it with a magnafying glass and cleaned it with a swab. And if its the float rubbing on something, what would cause that. There was only normal riding before this happened.

I'm puzzled. I just hope I don't ruin anything and learn something from this.

 

[biglou]

Not to worry. Pulling the carb off one of these kTm's is very simple. Take the seat, tank and shrouds off for easy access. Then just loosen the cap and carefully remove the slide from the top of the carb. Next, loosen the two clamps around the airbox and engine sides of the carb. Last, just twist her out of there. The rubber boot on the air box will let you finagle it enough to get it out. When you reinstall, just be sure the carb is level, there are notches in the airbox boot and engine intake boot that line up with notched on the carb's intake throat and output side to the engine. Just make sure those are lined up before you tighten the clamps back down. Leave the clamps loose until you get the throttle cable and slide back in the top of the carb.

 

[geremacheks]

Thanks BigLou. I love that word: simple. That kind of stuff is not in that fat KTM owners manual. I suppose I should get a shop manual.

I guess it's that removing the cap and then the slide from the carb that scares me a little. I haven't done that for decades and really didn't remember how it was done. Do you believe I annually ride in high altitudes and change the jets?....er...ah...I mean one jet. The main jet is all I have ever changed. If I now actually get to the cap and slide, I might find myself changing needles and needle jet positions. Wow, that would be like gradtuating to dirt-bike college.

Is anything going to fly out of there when I open the cap? You said do this CAREFULLY. And carb level--you mean in line with the wheels, I think. I think the carp tilts forward a little in its normal position. I maybe wrong about that.

I do feel better about it now. But I got this feeling that nothing was wrong with the carb float level, and I wish I didn't mess with it now. Maybe that's why the bowl is not going on. Really, there's plenty of room to get it back on, gas lines and vent tubes are off, guards are clear. Maybe I should try to rebend tab back to normal. The problem just has to be dirt. Though I can't find any.