BBR does the TTR engine in the CR bigwheel frames also.....kinda pricey. There are several other companies doing something similar, mostly with the XR100 engines bored and stroked to 120cc'c. DMC in California, Cartwright Conversions in Texas, are a couple. As the above posts state, for the dollar savings, bar mounts, taller seat, peg lowering might get you by for awhile. You could also do the YZ forks and extended swing arm thing. Check out the TTR post on www.thumpertalk.com