Post by motorhead on Aug 3, 2011 18:08:57 GMT -5
My buddy bought a 72cc kir for his 50cc and I was installing it for him. It came with a 47mm cylinder, 47mm piston, 47mm head and a new camshaft.
I set the flywheel and verified the piston position at TDC. Then I aligned the cam and had it timed up near perfect with the big hole in the cam perpendicular to the head plane with the 2 small holes on either side. Then when I put the rocker arms in place there is about 1/4 inch of play in the rocker arms, and they barely push the valves down. I thought I did something wrong so i put the cam on the 50cc head and when the rocker arms are placed on the 50cc head the rockers are snug as they should be. Both cams work fine on the 50cc head and rockers but both cams leave 1/4 inch of play in the rocker arms on the 72cc head. On further inspection the valves in the 50cc head come out farther than they do in the 72cc head.
I have installed many 80cc kits, and I have rebuilt many 50's, so yes I know what I am doing. Have any of you had this problem with 72cc heads?
I set the flywheel and verified the piston position at TDC. Then I aligned the cam and had it timed up near perfect with the big hole in the cam perpendicular to the head plane with the 2 small holes on either side. Then when I put the rocker arms in place there is about 1/4 inch of play in the rocker arms, and they barely push the valves down. I thought I did something wrong so i put the cam on the 50cc head and when the rocker arms are placed on the 50cc head the rockers are snug as they should be. Both cams work fine on the 50cc head and rockers but both cams leave 1/4 inch of play in the rocker arms on the 72cc head. On further inspection the valves in the 50cc head come out farther than they do in the 72cc head.
I have installed many 80cc kits, and I have rebuilt many 50's, so yes I know what I am doing. Have any of you had this problem with 72cc heads?
