Here's a weird one for the Group. I have a 78 YZ400 and an 82 YZ490. Right now the 400 is being used as a Hanger Queen (parts bike). However, the 400 motor would probably be better in the woods(smoother power, less vibe,quieter, 5 speed),and it has a clean DG pipe and silencer. You can see where I'm going with this. Does anyone have experience putting that motor in the 82 frame. I haven't gotten down to serious measuring yet, but the two motors' cases look identical. Also, how about the 82 490 carb on the 400 motor? I'm still looking for specs, but I think they are the same size.