Gas runs out of the carbs - Keihin CV

30771 Views 16 Replies 6 Participants Last post by mubeen, Jun 1, 2017

MCIntruder

Discussion Starter · Jul 13, 2013

I had to clean the carburetors ...... (4x 34mm Keihin CV). As I had the carbs off, I wanted to check/adjust the fuel level height. I “mounted” the carbs on a special made metalplate with the same angel as on the bike. The “gastank” was a 1 L lemonadebottle and the difference from gasolinelevel in the bottle and the bottom edge of the carburettorbody was about 45 cm (approx.. 10 cm more than a full gastank on the bike).
My problem is, that even though the float height is about 17 mm (as they should be) the fuel level height exceeds the recommended max at 1 mm above the carburettorbody many times. The height gets so high that the fuel runs out of the carbs (comes out of the Pilot Air Jet and/or Main Air Jet). Tried it a lot of times now and have even installed new fuel inlet valve needles to try to make up for the failure. I´ve also checked the mating surface of the float needle for corrosion, the upper carb vent lines etc. Nothing´s wrong here - I think.
I can´t figure out what the problem is/what I might do wrong???????????

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hubz14

· #2 · Jul 13, 2013 (Edited)

I want the top carb body line of where I push the float bowl under. Get it? I separate the bowl from body, that is my horizontal line.

I want to set my float level with the line. I don't measure with tool. I bend the tang so the flow stops and flows when I drop bowl within a mm or 2.

Again, I want a level line of the float to line up with the lower horizontal line of the carb body. I turn the gas container over so the fuel flows. I watch the flow stop the higher I raise the float.

Where did my float level land once I stopped flow? Lower than center? Higher than center? So I am more working the physical than relying on some bent up float you don't see [to to check the floats being level to each other] is higher than the other and you take that lower/higher measurement instead of a flowing static move you can physically see stop the flow.

Even your floats will have a gas line etched in it. Follow that old pattern.

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hubz14

· #6 · Jul 14, 2013

Another way is to stand the carb body so the horizontal line is now vertical. So you now let the floats close the needle by the angle they create.

Now, you push the float to see if the tang is pushing the pin's spring [if it has one] in the needle? If there is a gap between the tang and needle? See it? If the tang is pushing the the pin's spring like it collapsed it fully? Get it?

So you are making that float as vertical as it was horizontal. But this time you are not having your finger pushing up on the horizontal position. You are looking at the floats statically level on their own in the vertical position.

This is more, 'sweat the details.' Walk away from it for a day and go back to it with a fresh look. This is somewhat simple is the float via mm measurement and/or hand-eye the puppies.

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hubz14

· #12 · Jul 17, 2013

I agree with creed. I'll take a guess: are the two leaking on the left side? This makes me assume there is no center stand so the bike sat on a left angle. The gas level is now at the two left carbs, but the angle made the right two carbs dry out.

But with the gas deteriorating, a chemical reaction can cause the green stuff to eat at the brass. The tip may be made out of rubber so this may have a ring around the cone part, and this too can cause dripping.

So my theory is that the gas etching sort of points to what creed was saying. You have to change the needle and seat as a set. So the theory goes, I keep bumping up on friction and that causes heat. So as much as it cools with gas over it all the time, it still wears as if you rub both hands together and now which one remained cold? Which did not wear: that you think you can get away with the etching you didn't change or vice verse with the old needle reused on a new seat?

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