Had them done on Jade - 3 colors. No issues you mentioned. The outfit that did it - I'm sure they are the first bike wheels they've done though powder coating is prominently displayed on their sign. I cautioned them not to get the powder in the bearing races, in the disc screw holes, or inside where the drive cushions go. I said "I know you surely know that, but I just want to be sure we are clear on that". It's no big deal to keep the powder out of the innards. Install some screws in the disc holes, insert some matched size metal plugs in the bearing races (it's a mechanic shop too; they could use large wrench sockets); tape off the drive cushion area while spraying the powder. He ignored me and didn't block the powder in any of those places. He also f'd up the color, got the main green color so it was in 2 tones - on opposite sides of the same side of the wheels - meaning you see the color change when it turns. I made him redo that. He also took 3 times longer than he promised and did not call me once with status, as he promised. I had started him with plenty of extra time before Inzane - 2 months - I almost had to put dingy wheels on for the trip. I think it was $250 I paid for his incompetence. I refused to pay until he fixed it - in fact I put a stop on his check. He said going forward he would have to charge more due to the effort involved. I said he should be paid less. I had said, do a great job and I'll send all my friends over here. Accordingly I told them to NOT go there unless they want all these problems.
I had to run taps in the thread holes, and use a dremel with abrasive wheels carefully to remove it from the bearing surfaces and inside the drive cushion area. Now the bearings fall out when handling the wheels for tire changes unless I tape over them. Also when he roughened the aluminum for good adhesion, he didn't do it evenly where the clear powder was going - around the perimeter. I wanted that so no chance of chipping off the color when mounting tires. Now that color reflects unevenly. The green dosen't exactly match the Honda green but it's close enough. Per my reading, even companies that sell both paint and powder can't get them to match exactly. They age differently.
Other than that, they look good and clean up easily, look new and of course no more oxidization problems. Of course I balance the tires with internal media - specifically Ride-On.
Jess, just remove the valve stems. If you leave them on then replacing them will crack the powder where the wheel meets the stem and look bad. Their internals and rubber gaskets/O-rings won't survive the 400° oven so they would have to be replaced immediately anyway. I had no issue installing new metal stems.
Also when mounting the tires, be sure they are fully seated. If there's powder on the bead surface, it can cause the tire to not seat fully. I didn't notice that, then rode to Roanoke and the resulting vibration (which wasn't obvious at highway speed) busted the JB Weld holding 4 of the Rostra cruise control magnets on the spokes of the disc, threw them off and defeated the cruise control. I found the problem at Roanoke at town street speeds and the local Honda dealer just shot pressure into the tire and it seated. For free. Replaced the magnets when I got home.
BTW I could have done it myself, if my curing oven was big enough. I have powder coated small pieces for years; use our repurposed old kitchen oven which is in the shop.
