I'm leaving Thursday for a 2,500 mile trip. So today I put the bike on the stand to clean and lube the chain today. Afterwards while I stood behind the bike with it in running and in gear,  I noticed the chain moving side-to-side slightly. Once per revolution it moves out (away from the tire) about 4 mm. I can see that the brake disc and wheel are both true. All of the mounting bolts for the sprocket are tight. That tells me that the sprocket is warped. I have no idea how that happened unless it was somehow done when the new tire was put on, but my friend and I mounted the tire, and I'm 99.9% sure that we didn't get into the sprocket with anything. Either way, I've ridden about 1,100 miles since the tire change, and the bike doesn't feel any different at all with the sprocket as it is. Not even at triple digit speeds.
Has anyone here ever experienced a warped sprocket? If so, please share your experience. Since I don't know when or how it happened, I'm worried about taking such a long trip with it. I'm afraid that it could get worse. I'm on the fence trying to decide if I should order a new one and pay for next-day shipping and swap it out before I leave.

Has anyone here ever experienced a warped sprocket? If so, please share your experience. Since I don't know when or how it happened, I'm worried about taking such a long trip with it. I'm afraid that it could get worse. I'm on the fence trying to decide if I should order a new one and pay for next-day shipping and swap it out before I leave.

Do it - and avoid a possible 2500mi worrying-about-it distraction!

is the rear sprocket inline with front sprocket? the front sprocket has some wobble play when installed...

For a quick check, pull the sprocket off, lay it flat and see if it wobbles. Be sure to check both sides.

I think it would be pretty hard to warp the rear sprocket unless it was crashed or dropped. I would take the wheel back off and make sure the spacers are on correctly and the cush drive is in place and fully seated. Make sure there is nothing between the cush drive and rim. If it is still warped but only just by a hair I wouldnt worry about it.

I think it would be pretty hard to warp the rear sprocket unless it was crashed or dropped. I would take the wheel back off and make sure the spacers are on correctly and the cush drive is in place and fully seated. Make sure there is nothing between the cush drive and rim.

My thoughts exactly.  The cush drive not being fully seated would give you the same 'once per revolution' visual that you describe, and seems like a much more likely candidate than a warped sprocket.  When you spin the rear wheel, can you see any run-out where the cush drive assembly mates into the wheel?    

I think it would be pretty hard to warp the rear sprocket unless it was crashed or dropped. I would take the wheel back off and make sure the spacers are on correctly and the cush drive is in place and fully seated. Make sure there is nothing between the cush drive and rim. If it is still warped but only just by a hair I wouldnt worry about it.

I've never had the sprocket off, so I don't think the problem will be in the cush drive. I'm taking it apart this afternoon. I'll remove the sprocket and lay it on a flat surface and see if it's the problem. 

Usally when you mount a tire you take the sprocket off along with the cush drive. Was the tire mounted with the sprocket on?

Usally when you mount a tire you take the sprocket off along with the cush drive. Was the tire mounted with the sprocket on?

Yes, I never remove the sprocket to replace a tire. 

The sprocket is definitely bent. When laid flat on the counter top, it rises up almost 5 mm in one spot. The offset is spread out over about 9 teeth. I don't have a clue how it got bent, and it probably wouldn't get any worse, but wordsmith is right. I'm not heading out across the country distracted by worrying about it. I'm ordering a new one.

Sorry to hear that it is bent. Fix it and still head out on your trip with a piece of mine knowing that it is straight.

Whoa. Good thing you checked.

Should also check the bearing in the sprocket(clutch) hub as it may have been affected by any wobbling of the hub.
 
Cheers
 

This would be a good time to consider dropping 2 teeth (in the back), if your riding style and roads and upcoming trip would benefit.
You would then have FZ gearing, about 6% taller.
I did it and I like it.
I live near and ride the twisties in the Santa Cruz Mountains almost exclusively, and with the close gearing of this transmission, there's never a lack of choice in gears.

This would be a good time to consider dropping 2 teeth (in the back), if your riding style and roads and upcoming trip would benefit. You would then have FJ gearing, about 6% taller.
I did it and I like it.
I live near and ride the twisties in the Santa Cruz Mountains almost exclusively, and with the close gearing of this transmission, there's never a lack of choice in gears.

I went the opposite direction, -1 tooth on the counter shaft sprocket.  I cant imagine wanting taller gearing, as it is I rarely use 6th gear unless I'm in excess of 80mph, with taller gearing I would never get over 4k rpm.  This motor loves to be revved!!