Black Spark Plugs

[qwqb]

Well, the bike hasn't run since I got it, but when I pulled the plugs I noticed that the #1, #3, and #4 plugs are all quite black and fouled, whereas the #2 plug looks pretty dang clean. I've heard of the #2 plug fouling out because of the petcock, but I seem to have the opposite going on. I am wondering if this is an indication of any specific problem?

Then again, who knows what has happened in the time between the bike running, and me getting the bike. The PO could have switched around all the plugs for all I know.

It could also be the case that the #2 plug was badly fouled and was replaced recently. Haha I think I am answering my own question as I type this all out, but I am interested in any input you guys might have. I have the tank off the bike, is there a way to test that the petcock is in proper working order?

[79FiveFifty]

running rich, running lean, running rich, running rich.

you pretty much did solve your problem, somebody either replaced 1 plug more recently than the other 3, or if it's white it's running too lean.

replace them all, plugs are cheap enough to be disposable. once you get your bike running get some accurate readings on the plugs and tune from there.

#2 fouls if the petcock is no good and vacuum hose is leaking gas down in, plug would likely be wet when you removed if it were wet fouled.

[Steve]

Sounds like they are all set to run very rich, but there is a vacuum leak in #2, allowing it to run lean.

.

[Johno]

Battery charge

Make sure that you commence your base line with a fully charged battery.

Later model GS's with electronic ignition need a fully charged battery to achieve a nice fat blue spark.

Don't ask me how I know!

They run great with a fully charged well maintained battery. This will allow you to concentrate on the motor and fuel/air issues to get it right.

[paco13]

What Steve said