Today while riding I noticed what I thought was a bad chain, or bad chain & sprocket combo. The bike was bucking, kicking, & hesitating-almost like the engine was misfiring. As the day pressed on, I realized that this was only happening in 4th gear. In 4th under light acceleration, the bike will jerk and buck and you can hear the chain go from tension to slack, back to tension repeatedly. Shift into 3rd or 5th, and the problem immediately goes away. Under heavy acceleration in 4th, it feels like the bike tries to pull but then just starts slipping like you have pulled in the clutch. Let off the gas and it will start pulling again, but still bucking the entire time. Now the questions, has anyone experienced this before? And if so, what parts did you need to fix the problem? I know I will have to split the cases, not worried about that. But would like to order parts in advance before I tear into it so that the bike is down the least amount of time. I have access to parts from a donor bike, but would like to hear about any "surprises" waiting for me when I get in there. Hope everyone elses weekend went better than mine..