Tight Timing Chain

[GrouchyOle'Man]

Hello, On my 150cc GY6 after installing new chain guides (but not the tensioner) I find that my chain once installed on the CAM sprocket is SO tight, that the cam cannot even rest on its bearing journal on the end opposite the sprocket. I have had the cylinder off and the head off numerous times. Videos I have seen show substantial SLACK in the timing chain allowing one to easily correctly time the engine. I tried it with the cylinder and head dowels placed correctly and the 2 long head bolts in place and snugged up. There is some slack, but not enough. Has anyone else experienced this?