Originally Posted by Mingola2
My answers to your questions:
1)No, I am new to this.
2) I read a posting a few months ago of someone who did mount to his bike and loved it.
3) I don't have experience in tuning a carb.
I guess I might have gotten in over my head!
I wouldn't worry about getting in over your head! Assembling a bike with an engine requires very few tools.
Your honest response reflects a level headed attitude towards the whole thing...which really is #1 when attempting anything new.
Common sense is key with this project. Start with a stout, good qualty, bike. Most of the department store bikes have adequate frames. Some of them have wheels/tires that are not up to running at a sustained 20-25mph and will need to be upgraded.
Take your time assembling the bike...there is a lot of good info here on the forum, and quite a few who have successfully built several MB's that are here to help.
Now, back to your carb question:
I don't know for sure, but I would bet that the Mikuni is going to be jetted based on an engine that incorporates a reed valve type induction which will produce a lot more vacuum at the inlet. I would expect that, out-of-the-box, the mixture would be too lean. Again I'm just talking off the hip as I haven't even tried mine yet. I am fairly certain that it is going to require re-jetting, and a lengthy test and tune session to get it right.
I would use your kit carb to start with and become very familiar with how this engine works before attempting a major carb swap. The kit carb is very simple, and set-up right out of the box to work well.
Have fun with your build, and feel free to ask for help.