Serobot tends to think in terms of leaky or torn rubber diaphragms (one issue of many that exist with the petcock) and he likes his "tee in the vac tube, block off the carb port, run it in Prime test because it likely
is the best test to eliminate "petcock as a whole" from your list of issues.
Routy tends to think "low fuel flow due to stiff rubber" (one of the many petcock issues)
Verslagen tends to want you to go
rebuild the whole thing using a rebuild kit he found for about $22 shipped
I tend to want you to yank the whole failure prone thing and stick in a simple mechanical Raptor petcock that simply doesn't have these many different failure modes (and the whole host of different performance symptoms that they cause)
We all think the petcock causes a lot of symptoms that we don't want to chase through simply to find "its the petcock again". By running in prime you simply get some decent gas flow temporarily that lets us know that that portion of things is working or not.
If in result you suddenly go black smoke rich or spill gasoline all over your bike from the air box, that tells us if your petcock diaphragm is split or torn.
This too is a valid diagnostic test that tells us
which part of the petcock has failed this time. Serobot's tee test is good for eliminating "petcock as a whole" as an issue, this one lets you judge which portion has failed. Both work.
This one is a little more brutal messy though.Come on guys, we're making chicken soup here -- not borsch.
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Bill wants you to put seafoam in your bike to lubricate and clean your carb -- he believes seafoam has magical healing properties so he keeps telling people to put in way too much (low was 25% of the float bowl, high was "fill it up") which makes their bikes smoke some and run kinda funny. This is good in Bill's world, but in normal reality it just fogs up the water while other folks are trying to do troubleshooting based on what the bike is doing now.
Honesty requires me to state "it worked last time", so I will. Swacking the bowl a few times with the handle end of a big screw driver works too (and it costs a lot less and doesn't take 1.5 days) but filling up your bowl with seafoam does free up a float and needle assembly.