Author Topic: float height  (Read 3060 times)

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zert

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float height
« on: May 19, 2006, 10:03:56 PM »
hi,i was reading the topic "jetting" and noticed that sometimes checking the float height is required.I was wondering if when the float height is not good,should the bike not leaking fuel?
Wim

Offline KXcam22

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Re: float height
« Reply #1 on: May 20, 2006, 03:21:44 PM »
Zert,
  Yes it sometimes will leak but is hard to notice unless it is really pissing fuel.  Can give you poor fuel mileage. Can also be too low.  The float level affects jetting (too low make lean too high makes rich) so I guess thats why everyone mentions to check it before messing with jetting. Hope this helps. Cam.

zert

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Re: float height
« Reply #2 on: May 20, 2006, 07:55:43 PM »
well,i've got the next problem.The bike needs the same amounts of fuel when i riding on public roads then on the track.10 liters for 90 km,thats a lot!He is to rich in low rpm and perfect when i give full trottle.The sparkplug is black and wet but after a session on track its become brown.As soon as i let go of the trottle,the engine dies.The screw that make the bike idle is turned al the way in,and still nothing,dies in a second.After riding on public roads,it smokes like a steamtrain.The pilot is 50,main 162 and the needle is stock now,clip in the middle.I ride with a mixture 1/50 with motul 800.Could it be that the previous owner drilled the hole where the needle goes in out to a bigger diameter? :?
Once you are going in higher rpm's,its runs like hell,wheelies in every gear so the piston is not on his last km.Somebody got some ideas?
I live nearby the Belgium coast so the altitude is 0-20mtrs.
I also checkt the crankseals and the are oke.
Regards,
Wim

I hope i can make the bike go perfect because i'am the only two stroker between some 25 4-strokers :evil:

Offline FuriouSly

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Re: float height
« Reply #3 on: May 21, 2006, 01:57:06 AM »
   If the float height is set causing the fuel level to be too low in the bowl, it may suck air and cause a too lean condition.  If fuel level is too low, excess vibration and motion causes the fuel to bubble up/foam which could cause a too lean condition, but normally will push down on the float making it add more fuel.
   If float height is set causing fuel level to be too high in the bowl, you should have some leakage out of the overflow lines if you lean the bike over slightest from vertical.  Also, you should be able to see the fuel in carb "barrel" and in the airbox.
   If the float is too high you will get poor bottom end power, bogging and stalling ( too rich ).  The reason is the fuel is being forced up the jets into the carb "barrel" by gravity, because the overflow lines are usually higher than the "barrel" of the carb.  That's why when the fuel is left on and the float valve sticks open, sometimes your airbox and crankcase will fill with fuel before the fuel will start running out the overflows.
   If the screw with the spring around it is the one you are talking about, that is the idle screw. If it is all the way in ( raising the slide up ), then you are proabably too rich. Also make sure your air filter is clean since that will mimic too rich ( no enough air flow ).   
   The mixture screw is between the carb and the airbox, it adjusts how much air is mixed in the idle to 1/4 circuit.  If the mixture screw is between the carb and reeds, then it adjusts the amount of fuel added.  If you have the screw all the way in ( between carb and airbox ), that would make it richer ( less air added ).  If it is 4 turns out from fully closed, that generally means you need to go to a smaller pilot jet....  but get the float adjusted first ! ! !  A 50 pilot is pretty small though, even at sea level.  Make sure the mixture screw is around 2 turns out from fully closed.
    I am not an expert, but I hope this sparks some thoughts on "real world" gearheads and their bikes.

Sly
« Last Edit: May 21, 2006, 03:35:44 AM by FuriouSly »

Offline KXcam22

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Re: float height
« Reply #4 on: May 21, 2006, 11:59:45 AM »
Wim,
  We should be able to get your supermoto smoking the 4-strokes. Likely only the 525 should be close.  For your type of competition I would expect your bike would run best jetted spot on everywhere but then a bit over-rich (just a bit) at full throttle for max power.  What year is your bike?  Post your next in the jetting thread and we can continue there. Cam.

Offline KXcam22

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Re: float height
« Reply #5 on: May 21, 2006, 12:05:34 PM »
Wim,
  Forgot one thing.  Pop out your needle and make sure it is stock. Given your low elevation and present jetting your bike shouldn't be as rich as it sounds. Suprised it won't idle with a 50. CHeck the cutaway number on the carb slide as well. Also, any mods like a big bore? Some mods make the engine more efficient and require leaner jetting (when you would expect richer). Cam.