Posted 31 March 2011 - 06:22 PM
I have a 348 with your very exact problem, before I acquired it, the flywheel had snapped off with quite a bit of the crank, and has eaten part of the casing, as well as putting a hole in the front of the casing (which has been fixed with a very hard filler). I have ridden my bike (quite aggressively) for about 20hrs and it has been fine. The primary gear is only half on the end of the crank, and it hasn't broken off yet...(I hope I haven't just jinxed my next trial!) It also seems to run fine without mass of the flywheel, I believe riders used to skim the flywheel anyway to take some mass off it and make the bike rev quicker. I'm not sure about the torque, as I haven't ridden a 348 with the flywheel on, but I'm sure it would make a difference.
I have (eventually) managed to get my hands on a complete 348 engine (with an intact crank and flywheel), so I plan to swap the crank as mentioned above.
Here's some pics off my bike: (if you skip to picture 29, that's probably the best pic of the crank, and the primary gear only just on it)
I've also got some electronic copies of 348 manuals if you need them.