I've got a MB Black Death and I've recently noticed that when I'm running at speed at dawn/dusk or dark that one side of my exhaust has a red glow but not both. I'm assuming that the reason only one side is glowing is due to how the valve lash is adjusted? Does anyone else motors do this? Also, is this a bad thing that could be damaging the motor and should I be concerned about? Thanks.

The exhaust on both longtails I owned used to glow in the dark when running WOT. I guess I have never looked on my surface drive. Not as visible out back with a vertical engine. I never worried about it. Plugs looked good so I knew it wasn't lean.

One cylinder runs leaner than the other. With the right jetting and tuning, intake and head work, and the right carb, it can be evened out. It's nothing new, though.