We got a few bikes (99 YZ400 and 2001 TTR125) from the same customer earlier on this week. Too make a long story short, the YZ's head is trashed and the TTR needs an exhaust. So after calling the guy and telling him the news, he asks if we want the clapped out bike for some money off the repairs on the TTR. Uhhh.....Hell YEAH!! So TT'ers, any of you tried putting a 250 smoker engine into a YZ400 frame? and is there anything I should be prepared/watch out for? Also, suggestions on best motor to use ? I figured most any would do considering they are very similar, but if anyone has suggestions it would be appreciated. This is my first time trying a motor swap on a dirt bike so bare with me. I will also be parting out the bottom end and carb at some point in time so If anyone needs anything let me know.