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Discussion Starter #1
Hi
How tight is your float needle to seat connection ( valve). Without tank fuel cock been locked, there is small leak in my case. Checked carb out of my bike and with transparent hose very slow falling down fuel level got in the hose. Replaced float needle valves( older had a little weaker spring bumper) polished seats (no signs of worning out, smooth inside). In upside down position ( without bawls) with pressure of my cheeks, no bubble leak under the valve but with balloon( no gauge to measure psi etc), leak appeared with handy pressure. I am used to turn off fuel cock of tank just before turning of the engine,
but without that, fuel in engine oil and airbox be sure is gona be there. There is video on YouTube where guy shows hight pressure test of float needle seat valve but according to that I have an issue but no idea how to fix it.
 

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What carbs do you have? Keihin I assume? Is there any debris in your fuel tank? What are your floats set at?
 

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Discussion Starter #3
Hi,
I have Keihins...overhauled by mysellf last year and because Of fuel smell in engine oil I started to look for... level set to stock 17.5mm. No debrids in fuel...I used plastic fuel see through bottle and transparent hose for checking it to be sure to see clean fuel to eliminate debrid effect . By the way May fuel tank is also after overhaul ..also inside)
 

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Discussion Starter #4
I got it!!
As new needles installed, I focused on seats- with magnifying glass just small stria visible as explored the surface around the seat hole and then polished with drill and wooden dowels . Many times did so as long as pressure test showed bubles out of under the neadle space. Finaly checked the carbs -connected ( out of bike) to fuel tank with transparent hose...as long as carbs where full, needle valve shut off the fuel and no aditional fuel level movement afterwards.
My conclusion : If signs of small fuel leak ( fuel smell of engine oil and air filter, reach condition etc) think about that, make sure float needles are in good condition, than be patient, if non changable float seat, polish with wooden dowel many times unless you solve the leak. Check the result with carbs out of the bike connected to fuel tank througout the night. May be of help for someone else.
720594
720595
 

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You should still shut the petcock off when engine is not running. Why? Every needle-seat pair will either leak at some point, or get replaced or thrown out. Gravity, on the other hand, has proven 100% reliable since the beginning of time.

Do you have a picture of the seat after you polished it? Did you use any sort of compound, or just the wood? (I have used jeweler's rouge.)
 
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