Thanks for the tips and guidelines on porting this cylinders. I'm just light porting one 45mm bore Chinese cylinder. Transfer ports are a single channel without a divider because I could not find the quad transfer cylinder on the ebay. But the problem I have is low compression - 120psi, measured without base gasket with the squish of 0.65mm. The problem is that the squish band is only 2mm wide and then the combustion chamber is huge. I'm not going machining the cylinder, I would rather find a better cast cylinder on the ebay - quad port and smaller combustion chamber.
The quad ports are more reliable and robust, I grind them out on some saws just to gain maximum flow, but it depends weather you are building a full race job or a reliable work saw, also wow squish 0.65, I run one at 0.75 and that is really powerful but obviously puts more load on bearings.
Hello from Brazil my friend Can you try to help me, please? My chainsaw has a problem with excessive compression. But when I remove the spark plug the piston rotates normally. Even placing your finger in thze spark plug opening causes the piston to become extremely compressed again. Yesterday I installed a completely new cylinder and piston, but the problem remains. I changed the spark plug, removed the carburetor and exhaust fan, and still the problem remains. Do you have any idea what it could be? Can I send you a video showing the problem? I have been seeking help with this mystery on various social media channels, Instagram, RU-vid, but no one has been able to guess what could be causing the problem.
