This past weekend, I put a 47mm (70cc) piston and cylinder on my son's Kasea Mini 50. After initial startup I noticed no smoke at all. I started investigating the oil pump and injection system. I eventually made the decision to remove the system, something I wanted to do eventually anyway. My plan at this point is to get some quality premix (see what is locally available) and run it at 32:1.

So, my question is should I expect to have to rejet or adjust the stock carb on this thing? How does the larger displacement and premix affect the jetting requirements? My goal here is NOT ultimate power, but rather a no hassle, bulletproof quad. I am willing to sacrifice a little power in the name of safety if it means not having to fiddle with the carb on each ride.

Any advice?

 

32:1 is fine. I prefer Torco GP-7 (torcousa.com) or Klotz R-50 oils.
Let your plug color guide you on jetting. [img]i/expressions/face-icon-small-smile.gif[/img]

 

I will monitor plug color. But my question was more whether or not I should expect to have to rejet due to the switch to premix and the larger displacement. I would guess the bigger motor would require me to jet up, but that may be a poor assumption.

 

If I'm tuning a motor with no idea on which way to jet, I run it and see how it runs. A high rpm miss would indicate a bigger main jet to me.
Bigger cc=bigger jet? Could be, but a proper fuel mix for the vacuum draw on a 50cc may still be the correct mix for 70cc's.

Run it and see. I doubt you'll stick it if you just pay attention to how it's running.