Quote Originally Posted by iwanajohnson View Post
alrighth eres another question, I need an explination of ports and porting, for example on a square port motor, do ya make prts higher or wider to get different types of power out of them, that kinda stuff neone here go any basic explinations of that kinda stuff?
A couple of rules of thumb. Make small changes as you can quickly ruin a block. Find a book on the subject (Two-Stroke TUNER’S HANDBOOK By Gordon Jennings). Talk to someone who has modified the same engine you are working on so you can get the benefit of their mistakes (Fast Fred). Never make a port width more than 65% of the bore. HP is gained by making improvements throughout the engine. All engines have week links, and there is always room for improvement. Probably more and some hilarious stories.

Usually, increasing the port width usually increases torque. Increasing the port height usually increases max RPM. More RPM is usually more HP. Engines have RPM limitations based on rod to stroke length, piston ring type, material strengths and weight of moving parts. The piston’s mean speed should never exceed 3500 ft/min. At high RPM the is a very rapid de-acceleration as the piston stops at the top and comes back down. Depending on the ring type and thickness, at some RPM the ring will lift off their seat and will flutter. This usually breaks a cast iron ring into pieces about 1/16-inches long, just before the engine explodes into pieces. Ductile iron rings do not break, but the lube is blown past the cylinder walls and the engine sticks. There are equations of motion for these subjects that you can get from the named book, or other resources.

This is just the beginning, break a few engines, I did.
Neil Bass