I have rebuilt quite a few motors for guys on the board here. I have slowly been modding motors too, mostly for myself and experimenting. I am confident now that I am ready to do it more for other racers.

As far as rebuilding a motor I take the motor apart and check it over, especially the rod and crank pin wear. I pull out the front bearing and pull the carb off and clean the block in a high pressure washer. If the front bearing is still good I clean and regrease or oil. On most motors I see they need a pinch, I have found a very effective method that works very well and keeps it very round. I have not found a size yet I couldn't pinch. I have even made plugs to fix a sleeve someone has tried to pinch themselves.
I use Tko bearings and I have had very good luck with using Go parts in Novarossi based engines. Especially the Go rod, it is very strong and is only $18.69.

If you have any questions you can post it on here or Pm me.

Rex