Is there any general rule as to about how many main jet sizes to go up when removing the airbox and using high flow pod filter on a 125cc two stroke? If not , any suggestions on where to start? Also will it effect where the float level should be set at?

 

If you are increasing air to an engine, more than likely you are going to lean it out. Therefore would want to jet up, numerically.

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Since re-jetting is not an exact science, it's impossible to say precisely what size main you need with variables such as elev.& temp. To be on the safe side try three sizes fatter main jet and test ride & do a plug read. With the airflow you have it should be fairly close. If the plug is black or grey you need to go one size leaner or fatter, respectively. I would think that the float level should remain at factory specs as that has no effect on fuel/air mixture unless the float was lowered drastically.