I paint about 30 helmets a year in my shop for customers. I scuff them until they look flat, do the art work, then shoot 3 coats of good PPG clear over it. Go ride. As far as warranty goes, I can see where a dealer wouldn't want to sell a new scuffed helmet, but who would buy it anyway? Don't worry about that aspect of painting it.Good luck.

 

+1 Thin coats

 

I'm going to order a black Biltwell Megaflake soon and intend to paint blue metalflake flames on it.

Like this:

Street Chopper Magazine article that takes you through the entire process

 

Actually, that isn't true.

 

painted mine so ugly hopefully no one will steal it off the bike....

 

Hmmmm...that looks easy.

 

Go ahead and paint it. Lightly scuff it first and wipe with rubbing alcohol to clean. Krylon works well and it drys quick enough so that runs should not be a problem. If you get some blue 3M tape from your local auto paint supplier, you can try some design work with different colors. If you don't like what you did, just scuff and repaint. Not a big deal and not alot of $. Have fun with it.
Here's a Biltwell I just did with gold leaf and some pinstriping.




bigmikespinstriping.com