My motor has been making a weird ticking noise occasionally. It happens specifically when I'm accellerating up an incline at low RPMs. When I'm at high RPMs and in my power band I don't hear any ticking, but then again, the exhaust could be drowning it out. I've already adjusted all the rocker arms, and it can't be an exhaust leak because it only happens under certain conditions. Could this be a really serious problem?