I realize that I’m a little narrowly focused on Japanese stuff so if anyone would like to give any recommendations in the comments and throw in a review or whatever please do and we’ll take it from there.
I’ll try and categorize this a little as it grows but for now I’ll just do it by general size of the companies.
The “Big boys”!
Bikebandit. They do cover pretty much everything and you can find a surprising amount of vintage parts still available. I’ve never had a hint of trouble when using them.
Motorcycle Superstore. I buy a LOT of tires from these guys. Always very competitive on price and usually amazingly fast on delivery.
Parts-N-More. A big site with a great inventory for classic Japanese bikes. I use them a lot. Never a problem. Located in Canada but they ship to the US very reasonably.
The “Specialists”
Metro Racing. Vintage dirt bike restorations and the absolute coolest line of classic clothes out there. His bikes pepper this site. Really great stuff.
Airtech Streamlining. If it’s made out of fiberglass and fits on a motorcycle chances are they have it. And now carrying more than just body parts.
HVC Cycle For classic Yamaha and Kawasaki 2 stroke parts with a LOT of re-popped parts that were in danger of disappearing. I swear if you had a frame and a pile of cash you could almost build a new RD350 from scratch
Economy Cycle. 2 and 4 stroke parts. They’re always adding new stuff so check in often. Same as HVC. Lot’s of great re-pop and performance parts.
Z1 Enterprises. Another great site for all vintage Japanese bikes with a special emphasis on the Kawasaki Z and KZ series bikes.
JessBikes. If you’re into Kawasaki 2 strokes you HAVE to check him out. Very big (and highly reputable) on E-bay as well.
Mikes XS. If you’re into XS 650’s and you don’t know about this guy then you’ve been hiding under a rock somewhere. He’s so good that places like Parts-N-More just link you directly to his site. He also has a lot of crossover parts that will work on other bikes.
British Only. Just like the name says. You could build a (very expensive) bike from scratch with their catalog.
Well that’s it for now… But lots more to come. If I’ve missed you be sure to send me a reminder and a link.
Thanks everybody..
Reader Recommended:
Dave Clark – Brough Superior, UK
George Cohen – www.norton.uk.com – Norton Singles UK
Kirby Rowbotham – www.kirbyrowbotham.com – Norton Twins, UK
Norman White – www.normanwhite.co.uk – Norton Twins, UK
Mick Hemming – www.mickhemmings.co.uk – Norton Twins, UK
Andover Norton – www.andover-norton.co.uk – Norton Spares, UK
I have dealt with all of the above for various things and can highly recommend all of them.
Motorcycle Photo Of The Day 
If anyone want’s to add any sites we can add a “Reader Recommendations” section. Please leave some comments about them and we’ll go from there. Thanks!
http://www.oilyragclothing.com for some great biker shirts :0) keep up the good work.
Dave Clark – Brough Superior, UK
George Cohen – http://www.norton.uk.com – Norton Singles UK
Kirby Rowbotham – http://www.kirbyrowbotham.com – Norton Twins, UK
Norman White – http://www.normanwhite.co.uk – Norton Twins, UK
Mick Hemming – http://www.mickhemmings.co.uk – Norton Twins, UK
Andover Norton – http://www.andover-norton.co.uk – Norton Spares, UK
I have dealt with all of the above for various things and can highly recommend all of them.
Excellent Nicholas. Thanks!
http://www.nichecycle.com/
this is a good alternative also for Japanese bikes
How about http://www.chaparral-racing.com ? They tend to have the lowest prices on tires, but they also sell oem and aftermarket parts.
http://www.xs650chopper.com/ is a great site to get inspiration and ideas if you’re looking to build a Japanese Yamaha XS 650.
If you need good quality dampers, grommets or other rubber parts for old Yamaha bikes, this site is fantastic https://sumorubber.com. They have tons of reproduction parts, some that you can’t find anywhere else!