I think I have had a roller cam follower come apart.

[Bill Hilly]

I have ran the wheels off my Hawk every since I got it, but especially after warning the motor up. I have put about 2,500 miles on it since doing the motor some months ago. It's performed great, but today, as I was getting ready to park at Walmart, I heard two little metallic pings within seconds of each other. I thought it sounded like I ran over something, then as I was pulling into a parking spot , the motor got noisy, almost like a loud clicking, almost like a card in a bicycle spokes, but louder. I made absolutely sure that I hadn't lost oil, and drove it home on the back roads, about 6 miles, or so. I didn't try to make much power, but the motor ran alright, and would get noisier, and quieter, and occasionally act like the chain , or a transmission gear would jump a tooth. I figured it was probably a transmission issue, at worst, or the centrifugal oil filter coming loose at best. I figured I would pull the valve cover, before taking side cases off, and my exhaust valve has at least an 1/8th inch, or possibly 3/16th inch of clearance. I keep the valves adjusted regularly, and the locknut is still tight, everything looks normal under the valve cover, other than the exhaust valve having too much clearance. I have a feeling it would be a mistake to adjust the valve, and try starting it. I don't think the bike would have started good, or ran decent if the exhaust valve wasn't seating right, so the only thing I can figure is a bent pushrod, or the roller wheel coming off the follower. The bike was just at a slow unstressed speed when it happened. I think it's the roller, because I think that bouncing around in the works was probably my noise.
It's miserably hot here, so I may just slap the stock motor from my parts bike on it for now. I honestly have been thinking about selling either the Hawk, or KPX, because they both get used in about the same way now. I almost regretted doing the motor, and gearing, and tire type changes to the Hawk, because I got the KPX to be more if a road bike, with the knowledge that the Hawk was more of a back road bike, BUT, I ended up using it exactly like the KPX. I probably will eventually fix my warmed up motor, but I won't be in too much hurry. I will probably also go back to knobbies on the Hawk when the 50/50 tires wear out.
I am grateful it happened before I put it up for sale, because if someone had bought it, and it had engine trouble soon after, They would think I was a crook. LOL