Motorcycle Repair: 1982 maxim dirve shaft middle gear and wiring short., yamaha maxim, drive shaft

Question
I have a 1982 yamaha maxim. When i heard a noise coming from what sounded like some sort of rod knock or something it turned out to be not the driveshaft gear but the gear that is connected to the engine and that the drive shaft connects to on the side of the motor it has broken teeth so it knocks it looks very hard to remove and even get to the part is 349.00 and i have  a second engine but it was once seized but now turns freely and has mold and corroson on the outside but looks like it can be cleaned up shoulk i switch the engine. Now the probel with the engine that was once seized is that the main fuse pops and smokes and only 1 of the coils gets power the other works great what do i do?

Answer
Hi Tyler... First, DON'T RIDE till it's fixed. If any more teeth break off, they could get lodged in the gear and lock up your rear wheel!! Personally, I wouldn't use that second engine. Once seized, it should be rebuilt. I have had bikes "magically" unseize themselves, only to reseize a few miles down the road. I would also say that cuz you have a second motor, you can fore go needing to spend $349 on a new gear. Changing the primary drive gear isn't all that bad, but may require some specialty tools (air impact for one). I would call around to the various shops in your area and see if one of them will remove the gear from your second engine and install it in the first engine. The bill may be as high as the price of a new gear, but you'll be up and going again without any other problems!! If you want to save money and do it yourself, you need to get the shop manual for your bike and you may need to get/borrow some special tools. But honestly, I would not take out a perfectly good engine and replace it with a moldy-oldy with known problems... you will just be setting yourself up for more headaches.... Good Luck Tyler!!

Jack