My son has been competing in ATV motocross since 2009. We started off with an 50cc Apex ATV.
As the he grew older, gained speed the OEM engine was not enough and even aftermarket cylinders did not provide sufficient to be competitive and to gain top spots. On one side the issue was that the frame and the engine resulted in the much heavier set (OEM set around 120kg, i.e. 265 lbs) compared to solo bikes and aftermarket cylinders were essentially tuned for high RPM and HP rather than torque and mid section power gain.
So the only option really was to invest heavily in knowledge gain, tooling and start experimenting.
Countless hours into learning and experimenting not to mention the finances required I managed to work out the setup that was proper and provided the results needed.
But what I really lacked in the process was a place where to best get relevant information that would guide me on the way. Every so often I had found something on the internet, bookmarked it maybe, but usually not finding it again.
So the intention of this page is really to concentrate the load of information available out there, write article my own with my data and background, share information, provide calculators etc.
You will find lots of references on this page and I am really thankful for many of those who have helped me this road and shared their information.