Originally Posted by bairdco
i've stated my experiences with the stock petcock on a hopped-up motor, and proved to myself it wasn't providing enough fuel to my carb, but i'll just let that one go for now...
wait... i just re-read your post. you said stock motor.
Baird and I disputed about this a couple of years ago so I'll elaborate a little and repost a simple test that anyone can do to prove what I'm saying.
Before you do this test you must have a clean fuel tank, in-tank filter, petcock and in-line filter, if used.
Fill your fuel tank. Disconnect the fuel line from the carburetor and stick it in a container big enought to hold the fuel in the tank. If you have a stopwatch, good, if not just use the second hand on your watch or clock. Open the petcock and start timing how long it takes to drain your tank. Of course tank size will have a bearing on how long this process takes but generally speaking you're going to see an empty tank in something like five to ten minutes. This is assuming you are able to get a steady flow, not dripping, from the disconnected fuel line.
Now, reconnect the fuel line, refill your tank and go for a ride starting timing when the engine starts. If you can, run the bike at WOT (wide open throttle) until the tank runs dry. How long was your ride? I have no doubt that you rode your bike, even at WOT a heck of a lot longer than it too to drain the tank into a container.
I'll go so far as to challenge anyone, in spite of modifications, to run their tank dry while riding in less time that it took to drain it into a can. It ain't gonna happen.
If your engine uses a gravity flow fuel delivery system and your filters and petcock can deliver a steady stream of fuel, doesn't need to be a fire hose, then there is no way that the engine can consume fuel faster than it will free drain from the tank. Therefore I submit that petcock size has absolutely no bearing on how the engine runs. I have seen a couple of defective petcocks where the rubber insert wasn't drilled/molded correctly and a steady stream of fuel wasn't possible. And, we've all heard a hundred times, or more, about clogged fuel filters because someone didn't clean their fuel tank before installation.
Those are exceptions to my test. Your fuel delivery system must be functioning properly.
I'll stand by that. Sorry Baird. You and I usually agree on most things. This is one where we differ.