Check your float bowl level

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Written by Mr Tidy   
Friday, 11 June 2004

Reprinted by Permission from Mr Tidy's Tech Tips

Float Adjustment Procedure

Some symptons of a too high level are, 
  • The choke does not work properly.
  • You'll see liquid spitting in the end of the exhaust after initial start up.
  • The carbon deposit will not be uniform and you'll see streaks or liquid stains. 
  • Your exhaust pipes are eternally black no matter what you set your jetting at. 

Use a good set of needle nose vise grips to break the tightness of the screws that hold the float bowl to the carburetor body.  Others have used a Dremel grinding tool with a cut-off wheel and cut a slot for a slotted screwdriver, or even cut the head off if worse comes to worse.  Replace with Allen head screws.
 

Can this drain pipe be adjusted to point down or towards the outside of the bike? 

The drain pipe is fixed, so don't try to move it.
 

 How does the tube attach to the bottom of the carb

To the drain pipe mentioned on the bottom of the float bowl.

 It appears that the 1/8 inch will work but it is REAL TIGHT.  the drain
 pipe (nipple) on the bottom of the carb points inwards towards the motor.  The tube must attach, make a 90 degree downward turn then another 90 degree turn towards the outside of the carb, then another 90 degree turn upwards alongside the carb. 

 There is an allen head screw on the bottom of the float bowl facing the rear.  You open it to drain the bowl. Then leave it open and put your clear tube on it.  Try to keep it level underneath and run it up along side the side of the carb towards the front. The measurement must be taken at the front of the carb, because the bowl slants down in the rear. With tube in place and fuel tank petcock open, turn on the key. The pump will activate and fill the tube and bowl and stop when the floats cut it off. The level in the tube will indicate the level in the bowl if you have done it correctly. There should be no bubbles in the tube.  If you move the tube slightly up or down the level should correct itself and return to the same level. The manual recommends 1 to 2mm below the mating surface.  Set the level according to the book, If you are 1 to 2mm above, leave it alone. 

 Note from Cal /LtoR
On the float level....there are two mating surfaces, a "front (air cleaner side), and a back (intake side)...the back is 11MMs higher than the front. I had set my level using the front mating surface as a reference...since then I have had a problem of "running out of gas" if I do a full throttle run through the gears, at about 85 in fourth the bike would "stutter", back of on the throttle for a few secs and away you could go. Thanks to Wanderndude for pointing out that the mating surface to use is the back mating surface....if you look in the manual, I forget the page, it does appear to be the back mating surface they are referencing but no where in print (unless I skipped over it) does it make this statement. 

 



Questions should be asked in our forum (Use discuss link below). The forum is very active and you stand a good chance of getting your questions answered there. If you would like to leave feedback for the author, or have additional information you think will benefit others, please use the comment section at the bottom of this page.

Discuss this article on the forums. (10 posts)


DISCLAIMER: This information and procedure is provided as a courtesy and is for informational purposes only.  Neither the publishers nor the authors accept any responsibility for the accuracy, applicability, or suitability of this procedure.  You assume all risks associated with the use of this information.  NEITHER THE PUBLISHERs NOR THE AUTHORs SHALL IN ANY EVENT BE LIABLE FOR ANY DIRECT, INDIRECT, PUNITIVE, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, OF ANY NATURE ARISING OUT OF OR IN ANY WAY CONNECTED WITH THE USE OR MISUSE OF THIS INFORMATION OR LACK OF INFORMATION.  Any type of modification or service work on your motorcycle should always be performed by a professional mechanic. If performed incorrectly, this procedure may endanger the safety of you and others on your motorcycle and possibly invalidate your manufacturer’s warranty.


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  Comments (6)
03 R* Silver Edition
Written by unclebrm, on 04-20-2012 23:27
For the past year I have had a severe problem with carb puking...or at least that is what I have heard it called. I have had 3 needles put in and it still leaks fuel about 75% of the time when I stop and turn the engine off. None of the mechanics have looked at the float. Any ideas?
2000 Float Level Update
Written by texasscott1, on 01-23-2012 21:38
In 2000 Yamaha issued an update concerning the float level for the 1600. Instead of 2-3 mm's below the bowl mating surface the level is supposed to be set at 4-5 mm's ABOVE the bowl mating surface.
Written by emma12, on 01-17-2011 09:07
the heater broke on my mikuni 40mm carb. is there a cheaper heater avilable? 
vern
float setting
Written by bullfrogsierra, on 11-10-2009 05:37
i read somewhere on this thread about using some calipers to measure 7mm from the top edge of the float to the mating surface? is this right :?
Written by onefastbob, on 07-26-2008 08:36
I would assume that the bike needs to be level and not on the kick stand for this check?!?!
Aloha !
Written by Xman, on 04-01-2007 22:52
Aloha I have done the no pump mod and it is working fine I thought this mite help others I went to my local pet shop and Bought a piece of vinyl aquarium air line the smallest one they had and it made it was easy to set up the float for me I hope this helps A hui hou Jerry aka
http://i85.photobucket.com/albums/k56/jcjr-2006/float2.jpg[/IMG]

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