What's the benchmark when measuring floats with the clear tube method?

[t3rmin]

Carb specs for my bike list "fuel level" as 5mm. So if I'm doing the clear tube attached to the drain method, that means it should come to 5mm below the seam where the bowl meets the carb body...?

I'm trying to work out some mixture issues and there's lots of conflicting/lacking info in the archives on this method.

[Steve]

That is exactly how my 850 manual shows it.


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[t3rmin]

Thanks, Steve. And I know this has been addressed recently, but I want to hear it again (straight out of a manual, hopefully). Does the bike need to be running? I measured them yesterday and the level would drop by about 3mm with the bike on (which somewhat surprised me), so it would seem to be an important detail.

[Nessism]

If you put the petcock in the prime position, allowing fuel to flow with the engine off, wouldn't the level be the same regardless of whether the engine is running or not?

[Killer2600]

If you put the petcock in the prime position, allowing fuel to flow with the engine off, wouldn't the level be the same regardless of whether the engine is running or not?

No the engine sucks up the fuel so the level drops to a point where the amount of fuel let in just about equals the amount going out

As for whether or not the engine needs to be running, I believe it has to be running--at least it does if your doing the suzuki outlined method with the tool they use.

[t3rmin]

If you put the petcock in the prime position, allowing fuel to flow with the engine off, wouldn't the level be the same regardless of whether the engine is running or not?

I didn't think so either, but I tried it myself and you can watch the level go down 2-3mm when you start the motor.