Typically, welding like that will actually make the bearing fit tighter, if it's done with the bearing race already removed. I've never tried doing it with the race in place, so your result could be different. If you weld it like that without the bearing race installed, the weld bead will shrink as it cools, and reduce the diameter of the bore in the case. With more extensive welding, I've had it tighten up so much that I had to clean it up in the mill with a boring bar, just to be able to install the race. It sounds like you've got a similar effect, but maybe a little less because you still had the race installed. If you still have to heat the case and chill the race to install it, it's probably fine. If it was mine, I'd go ahead and use it for a street bike engine. If it was for a race bike, I'd probably either find replacement cases, or weld some reinforcing plates and gussets to the case. No matter what you do, if you put a lot of mileage on it, or hammer it really hard on a regular basis, the bearing fit will eventually get looser. But it will probably still run just fine that way. My experience with race engines with stock cases has been that the only way to keep the bearing race from eventually turning is to pin it in place, but that's probably unnecessary for a road bike. The Maney cases seem to hold their fit a lot better, probably because they are cast in a higher tensile strength alloy, and are thicker in the main bearing area.
Ken
