If there the same year it should fit.
1988-1991 yz250 motors are completely interchangeable. Some parts like the cylinder head use the same casting from 1988-1996. Note: although interchangeable the cylinder ports and cylinder head combustion chamber shape differ form year to year. The optimum setup for a 1990 yz250 is a 1991 cylinder with a 1992 head.
torque de yz 250
20 ft lbs
No because the cylinder is twice the size of the old one if u put a 250 head on. Then the bolts wouldn't line up and it u had 250cc 2 stroke power on the 125 trannie you would be screwed
Generally the nominal diameter of cylinder bore is kept little smaller at cylinder head than at the bottom. The engine head will be generally heat and it tends to expand for these high temperatures. To prevent the bore diameter at head to exceed diameter at bottom,piston engine bore is ground with a slight choke.
a far from my knowledge one piston stroke is the distance the piston head traveled from bottom end of cylinder to top end of the cylinder
No
Fixed bits: cylinder head , cylinder barrel , crankcase. Moving bits: cams , valves , pistons , con rods , crankshaft.
The cylinder head is located on top of the engine. The spark plugs thread into the cylinder head(s).....
It is the space between the top of the piston and the bottom of the cylinder head. Great care should be used when putting an engine back together to make sure the bump clearance is not 0 so that the piston will not hit the head cylinder.
Cracks can be welded and then the head can be resurfaced.
Cylinder head 43Nm Cylinder head cover 10Nm