freeair

by raising the exhaust timing you will gain in rpms but torque will suffer. you can slighly widen the exhaust port and both match this area with the manifold and polish smooth, also check how the piston looks at BDC looking through the port, if its not flush with the port base you can machine down this base to suit . before you start any of this you must firstly measure [ head clearance ] squish band clearance with the good old solder test. if you feel there is room to remove a few thou , do so by either machining from the cylinder base / mill the top of case or the easy way , remove or replace the cylinder base gasket with a thinner copper gasket, this is instant power. the slanted sparkplug cylinder heads are not the best for modding compared to the vertical plug type that has a real dome and squish band but more compression does equal more power. you can also check your intake manifold to cylinder head to make sure the openings are identical without any slight restrictions such as a slightly smaller diameter manifold block to cylinder intake opening. there is alot you can do to this particular engine to gain heaps of power torque and still keep and gain rpm,s.