2 Stroke Porting Calculator

Have you tuned a two stroke and wondered when your exhaust and transfer ports need to open in order to get maximum power at the rpm you want? 2 Stroke Porting will tell you. Simply move the slider to the rpm where you want the maximum power to be and it will display the required exhaust and transfer openings.



The openings will be displayed in - degrees After Top Dead Centre (ATDC), degrees duration and, for those who prefer distance measurements - Distances in millimetres from piston at Top Dead Centre to port opening (for distance measurements, make sure you insert your Stroke and Connector Rod lengths). You can also measure from the top of the cylinder surface, but if your piston doesn’t reach the top at TDC, you’ll need to add this to the measurement displayed in the app



2 Stroke Porting is also good for assessing what state of tune you already have. Either measure the port distances from TDC, or measure opening time, ATDC, with a degree wheel, slide the slider so the it shows the port opening at this measurement and read off the rpm where the maximum power should be.



2 Stroke Porting will also highlight to you whether your existing exhaust and transfer timings are in tune with each other. On some older two strokes the relationship between the exhaust and transfers was inadequate. Slide the slider to the degrees, or distance measurement, where your exhaust port opens, then you will have a degree and millimetre measurement of where your transfers should open and you can check your engine to see if they do.



2 stroke Porting is a really good guide to establish these measurements and will give you very close figures to work from. To maximise your output ensure you have a good exhaust, correct size carb and a cylinder head with well designed squish area