Can she still cosign for me to get a bike with good credit but a lien on her credit card?

She hasn't got good credit if she has a lien on her credit card, dah ! So, no, she cant cosign you.

Surely she has some clue by now how high interest rates are and how fast it accumulates... so why in the world does she want to add to her debt????

It will be up to the bank. Or company that is doing the loan for the motorcycle. They may, it all depends on her credit score. Also there is not a "lien" on a credit card, it can be over balance, past due, in collections, even have a judgement against her.

A lien is a legal encumbrance placed on real property to satisfy a debt. So one cannot have a lien on a credit card. However, the credit card issuer could have a lien against some property she owns. Not all liens indicate bad credit. Lenders who make loans for real property like real estate or cars will place a lien against the real property.

So its not clear what she has. It will be up to the lender to determine whether her credit is good enough to grant the loan.

A lien is a legal encumbrance placed on real property to satisfy a debt. ...

Or on personal property. It depends upon the type of lien.

But yes, it will be a decision for the lender to make.