I've got a BW200 which appears to have a similar motor to the TW200. The top end is making a good bit of noise. I thought it was because the timing chain was worn out but when I was replacing the timing chain, I noticed that the cam was moving radially in the head a pretty good bit. Has anyone run across this before? It looks like I can replace the cam collar but I'm wondering if the head is salvageable since there is no bearing in there to replace. I'm pretty sure it's shot but I wanted to get some suggestions before I start buying parts. Here's a youtube video to help explain the issue a little better. Thanks!
http://www.youtube.com/watch?v=uBomM92X3eQ
http://www.youtube.com/watch?v=uBomM92X3eQ