Gas runs out of the carbs - Keihin CV

30769 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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joker14n

· #14 · Jul 19, 2013 (Edited)

You need to inspect the needle valve assembly and seat under the biggest magnifier you can use...any corrosion anywhere is a failure waiting to happen. Then check the floats to make sure that they actually "float" as opposed to sinking.

I just finished repairing a set of those exact carbs for an '87 750 ninja. Forget about doing anything on the bike...doesn't work that way. You can check the float level on the bike by running a hose connected to the drain of each bowl to verify correct height. (in the manual) If you have any issues with these, I can probably help if you wanna pm me, and always ...NO questionable parts, and CLEAN as possible are the best starting points. without those, you're just gonna get really good at R&R of the carbs

FYI, if fuel is spilling out of the carbs, your needle valve is either wasted or you've got some shit in there. Float height won't get you there

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