I am near the end of my project and have an issue. The engine has been upgraded to a Powerhorse 414 at about 13.5 hp. I'm using a comet 40 setup also. The original jackshat was 5/8 but I upgraded to 3/4. The sprocket ratio is 10:54 As far as i can tell everything is lined up well. Driver to driven and jackshaft to rear end. I first destroyed a double sealed Heim bearing and thought it was because I nicked the bearing seal putting it in and figure it may have bounds the bearings causing heat and friction. I temporarily put one of the original unsealed bearings in until I picked up a sealed one. I've been finishing up some work on it and taking short rides in the neighborhood and tonight that bearing was destroyed. I'm wondering if the torque produced by this engine pulls to hard on the jackshaft compressing the bearing against the plate it is mounted in. That original plate is only about 1/16" thick and would create a small pressure point on the bearing housing resulting in failure. Another possibility could be a tiny misalignment between the two jackshaft bearings. Or possibly could it be as simple with this bearing as running out of grease and burning up. I've got 1/4" thick bearing plates (like a huge washer) that is meant to be welded but since I already powdercoated the frame. I was thinking I could bolt the plate to the original plate giving a much thicker plate to support the bearing housing. Has anybody had this problem? How did you fix it? Any ideas from anyone?