Author Topic: whats the best way to measure float height  (Read 9015 times)

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Offline kiwimonster

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whats the best way to measure float height
« on: November 05, 2008, 10:23:14 AM »
ive never checked mine . how do you check it , what do you actualy measure.any help would be awesome.
d c scrivens

Offline kiwimonster

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Re: whats the best way to measure float height
« Reply #1 on: November 07, 2008, 11:31:46 AM »
anybody
d c scrivens

Offline ID KX500

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Re: whats the best way to measure float height
« Reply #2 on: November 07, 2008, 11:40:58 AM »
I'd like to know too. Mine isn't shutting off when bike is leaning over slightly, it over flows.
ID KX500
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Offline kaw rider

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Re: whats the best way to measure float height
« Reply #3 on: November 07, 2008, 01:21:18 PM »
there a tube that  check external, i think it's a better way of checking. i'll see if i can find a picture of it.

Offline Johnniespeed

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Re: whats the best way to measure float height
« Reply #4 on: November 07, 2008, 01:27:31 PM »
I dont know the answer for the KX500, but on many carbs the float has a seam that should be parallel to the gasket surface when the carb is inverted.
On a red bike I owned the measurement was from the gasket surface to the botttom of the float with the carb inverted.
 I didnt take the time to find the spec, but once you know the diminsion, and once the carb is inverted, you should be able to figure out the location for the diminsion.
  The actual measurement or adjustment should not change with time, however the float can sink, or become waterlogged ( gas logged). But most likely the needle and seat will have debris or wear causing the overflow.
 Post the spec when you find it please. John
Spring is here and the Mighty 500 wants to ride.
 2004 KX500 E16
 Michigan has the best groomed and mapped trail system, check out the Cycle Conservation Club of Michigan trail maps.

Offline Johnniespeed

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Re: whats the best way to measure float height
« Reply #5 on: November 07, 2008, 01:40:12 PM »
Ok I cheated and used the search function. The KX500 2000 to 2004 float height is 16mm +or- 1mm.
 And I read there is an easier way to check and adjust it located in the jetting section. I did not  look for that.
It is my guess that the 15 to 17mm  is the distance from the float bowl gasket surface to the bottom of the float when the carb is upside down.
 I am sure someone else will know for sure.
 John
Spring is here and the Mighty 500 wants to ride.
 2004 KX500 E16
 Michigan has the best groomed and mapped trail system, check out the Cycle Conservation Club of Michigan trail maps.

Offline Friar-Tuck

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Re: whats the best way to measure float height
« Reply #6 on: November 07, 2008, 01:48:23 PM »
 I'll try to find something a little better, but check these out and see if it's any clearer.
Kx500 float levels
       Mikuni vm38ss 24.6-26.6  '84
       Mikuni VM40ss 19.1         '85-'86
       Mikuni VM38ss 27mm       '87
 
 the PWK's are 15-17mm   ('88-02')   my clymer is '83-'02
 I'm pretty sure the '02-'04 also use the PWK 39.5

http://www.dirtrider.com/tech/141_0707_keihin_fcr_carb_rebuild/photo_10.html
http://justkdx.dirtrider.net/floatlevel.html
 
Tuck \o/
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Offline Friar-Tuck

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Re: whats the best way to measure float height
« Reply #7 on: November 07, 2008, 01:49:34 PM »
 Soory Guy's I've been tryin' to post and keep getting kicked out...
One more,
http://www.salocal.com/sohc/tech/carb/asmpg_mgs/flthgt.htm
  Tuck \o/
« Last Edit: November 07, 2008, 02:14:38 PM by Friar-Tuck »
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Offline BDI

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Re: whats the best way to measure float height
« Reply #8 on: November 08, 2008, 06:39:10 AM »
You should check your float with the carb laying on its side, not upside down. The idea is to have the metal tang on the float just barely come into contact with the spring loaded nipple on the float needle valve without compressing it. The correct height for most modern motorcycle carbs is when the seem on the float is parallel with the gasket surface of the float bowl. If your carb is overflowing gas You either need to clean the carb or replace the needle valve or possibly the float. float adjustment will not cause this as far as I know.
« Last Edit: November 08, 2008, 06:41:35 AM by BDI »
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Offline ID KX500

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Re: whats the best way to measure float height
« Reply #9 on: November 08, 2008, 10:22:11 AM »
Thanks BDI I'm guessing my needle then. I'll try that.
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Offline KXcam22

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Re: whats the best way to measure float height
« Reply #10 on: November 08, 2008, 01:18:36 PM »
If you search the jetting sticky you will find a great way to check your float height. Cam.

Offline barryadam

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Re: whats the best way to measure float height
« Reply #11 on: November 10, 2008, 11:05:43 AM »
Measuring the actual float and valve performance is easier than try to guess when the tab contacts the pin and when the valve actually SEATS enough to shut off.
Strap the carb to a vertical board to make sure the float bowl gasket is in a perfectly horizontal plane.  I actually have this set up to sit at the same height on my bike lift as the carb sits in the bike, and connect the fuel line to the bike tank.  Buy a spare float bowl drain plug from Sudco, drill a hole in the center and install a brass tube.  When you connect a short length of clear poly tubing on the drain bolt and bend it up beside the carb body, you get a simple level gauge that shows the actual performance of the float valve.
Just like the manual shows, except the special tool will cost you about $3
Remember not to dip the poly tubing down and up as it will not relieve an "overfill" condition in the tube.
You can set the valve to shut off at EXACTLY 1 mm below the gasket line ( I think that's what the specs are).
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Offline maddoggy

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Re: whats the best way to measure float height
« Reply #12 on: November 10, 2008, 11:36:54 AM »
Measuring the actual float and valve performance is easier than try to guess when the tab contacts the pin and when the valve actually SEATS enough to shut off.
Strap the carb to a vertical board to make sure the float bowl gasket is in a perfectly horizontal plane.  I actually have this set up to sit at the same height on my bike lift as the carb sits in the bike, and connect the fuel line to the bike tank.  Buy a spare float bowl drain plug from Sudco, drill a hole in the center and install a brass tube.  When you connect a short length of clear poly tubing on the drain bolt and bend it up beside the carb body, you get a simple level gauge that shows the actual performance of the float valve.
Just like the manual shows, except the special tool will cost you about $3
Remember not to dip the poly tubing down and up as it will not relieve an "overfill" condition in the tube.
You can set the valve to shut off at EXACTLY 1 mm below the gasket line ( I think that's what the specs are).
great info there barryadam and great inovation, you are right on the money. i love building specialty tools instead of buying them from the shop, or having someone else do the work due to not having the proper tools.   MADDOGGY

Offline BDI

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Re: whats the best way to measure float height
« Reply #13 on: November 10, 2008, 01:30:14 PM »
This is the most accurate way to set your float, It is especially helpfull when dealing with old and worn parts that do not perform as they should. It helps you get the fuel level right even if the parts are questionable. I have found though that if the carb parts are in tip top condition, it is unnecessary and that bench setting the float to the factory spec works just fine and saves a bunch of time. It also saves wear and tear on the carbs do to the fact that when the needle and seat are worn you wind up chasing the proper fuel level all over the place, taking the carb appart multible times only to see the fuel level change unpredictably. I think for the average Joe the best thing to do is make sure your needle,seat and float are all in good working order and set the float height to spec and then worrie about something else like ridding. If the rubber tip on your needle shows wear of any kind you should replace it. Even if it just has a faint little shiny ring on it where it rest in the seat, go get a new one.
« Last Edit: November 10, 2008, 01:31:57 PM by BDI »
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Offline 4stroker

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Re: whats the best way to measure float height
« Reply #14 on: November 10, 2008, 02:59:03 PM »
with the PWK's on my banshees i have always just removed the fuel bowl, inverted the carb and blow through the fuel hose with my mouth, and move the float with my fingers until you can hear the air coming out the needle and seat.  adjust the tang so that air comes out when the seam in the float is parralell with the gasket surface...