KX Riders
Maintenance & Technical => KX500 Original => Topic started by: slow600 on July 16, 2010, 11:13:19 AM
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adjusted my float height last night, apparantly i didnt do it right cause now it runs out of the overflow at all times. it did not do this before i messed with it. can someone show me in the jetting section on how to do it correctly. i looked for it but 52 pages is a lot to read through.
what i was trying to do was keep the fuel from running out when jump or go over bumps, and possibly attempt to make the bike run leaner. i thought that meant i should lower the float height, is this correct or backwards? i read somewhere on here that an easier way to set the float than measuring was to set the seam on the float parallel to the gasket surface. is this accurate? thanks
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I have a exrta carb so I used my extra bowl drain/plug- drilled a hole in it the same size as a fuel hose,
put a 10 in piece of hose in it.
I use this so I can see how high the fuel level is.
The fuel level should be the same as the gasket-
Hold the line higher than needed so fuel don`t run all over the place.
I know this is no help if you have no extra draig but it is the best way to set your float.
Take a lil time and read some of the posts here.
These guys are good at explaining how to do stuff like this.
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I just went through this. Here is what I did.
My bike was going through an obscene amount of fuel while woods riding. There is no way it could have burned that much fuel so I thought there is something to this overflow/float height thing. I read the whole thread on jetting, researched the special float height tool, called sudco to find out how much bowl plugs cost and researched the Keihin method of setting the float height. After all this research I decided to go with KXCams "blow through the tubing method."
When I talked to sudco they said the most overlooked and most important part of the carb is the float needle. It is not cheap. I paid $18. He is sudco, he knows more than me so I went with it along with a handful of pilot jets. Your overflow problem may be related to a wore out float needle.
The float height is supposed to be 16mm +-1 from the gasket surface to the part of the float farthest from the gasket surface. After reading KXCams contribution to the jetting thread I decided to set the float 1mm below the suggested range ie. 18mm.
I put fuel line onto the carb fuel inlet port. While holding the carb upright, I blew through the fuel line as I slowly raised the float until the float needle engaged the seat which cut off the air I was blowing in the fuel line. At the point where the air stopped, I held the float steady against the center guts of the carb and measured the float height with a caliper. I repeated this with the carb in various attitudes to make sure my method was consistent. I tweaked the tab until my distance was a solid 18mm and called it good.
I went out riding tonight and went through much less fuel. It still goes through more fuel than what I think it should for woods riding. I am still rich on the pilot. I am hopeful that getting the pilot right will further enhance the range. If not, I may go another mm on the float height??
Hope this helps.
Fitz
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I can't seem to get this to pop up full size, Click on it to enlarge! :-D
(http://www.kxriders.com/forums/index.php?action=dlattach;topic=5833.0;attach=5888;image)
The first link is kinda old however you get the idea, :|
http://www.salocal.com/sohc/tech/carb/asmpg_mgs/flthgt.htm
http://justkdx.dirtrider.net/floatlevel.html
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Try this link.
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thanks for the links. got adjusted to 18mm, no more fuel out of the overflow.
now another question. after adjusting the float(lowered) my bike no longer surges on decel. how is this possible? i always thought the surge issue was a lean condition when closing the throttle. im extremely happy but what gives?
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It seems to me that by lowering your float height it was enough to keep fuel from being drawn through the needle jet.
There is lots of threads on the surge, and I certainly don't have proof of what causes the condition.
I do have a question though, Do you have your bike set up to Idle?
\o/
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im not exactly sure what you mean. do you mean does my bike hold an idle? yes, the longest i have sat at an intersection was 5-10 min and it idled the whole time.
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Did you put the overflow line into a can or something to see if it was still leaking? I have my float set to around 18 with positive results but have not checked to see if it has totally solved the problem. I would be tempted to go to 19 if I am still loosing gas.
Interesting observation about the surge. I will try and take notice on mine the next time out.
Did or does your bike have a tendency to go rich on a down hill line? Before I made the float height adjustment, mine would trend rich on steeper angles. I compensated by adding a little throttle and or cleaning it out halfway down the hill . It tried to foul a plug on a downhill line a while back and I had a hard time getting it started. It seemed better but not far from perfect after making the adjustment.
Fitz
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i do have a catch can, the fuel only comes out on a wheelie or stoppy now. my bike is a road bike so im not sure on the down hill issue.
im happy but puzzled on the surge issue that is now gone, it seems kinda backward. it will only give a couple of bucks if wide open then chopping the throttle, it used to buck constantly anytime i wasnt accelerating. maybe someone who is smarter than me will chime in :-D