Originally Posted by BarelyAWake
The reason "regulating" your fuel with the petcock is "frowned on" is pretty simple, far from a precision instrument - there's no way to be sure you're not starving your engine for fuel, more importantly the oil that's in it - it's pretty random the amount of flow you'll get with that method.
Running lean can cause serious
damage to to your engine, it's easy enough to adjust your fuel/air mix properly by examining your spark plug's coloration and adjusting the carb needle's clip appropriately.
You should always warm the engine up completely by riding it around normally for at least
15 minutes and let the engine cool down thoroughly before attempting to remove the plug. This way you'll get an accurate reading and letting it cool will help prevent stripped threads when removing the plug.
Your plug should look like this (or a lil darker if yer paranoid/new engine);
If it's black - move the clip up one notch, if it's white - move it down (towards the pointy end) one notch.
Anything else is dangerous guesswork. If yer four-stroking a little from time to time - that's pretty normal, if you try and "fix" it w/o even looking at your plug odds are yer gonna run it lean.
Hey, There you go... I was waiting on someone to correct me on the matter. I was doing that for a while, and it ran great, but my motor mount recently broke, so I guess I didnt stick around long enough to see the long/short term effect.. Thanks.. Thanks Barelyawake for the input. VW