Knock in the motor

[DRedel]

So I am getting mixed info on my motor problem. My mechanic is pulling off the cams to be able to look down in for a broken spring or valve problems. A friend of a friend who knows about bikes said that it is bs and the knock is too loud to be top end problems. He thinks it's a broken rod or piston rattle. When I said this to the mechanic he said that if that were the case the knock would happen constantly. Now the knock comes and goes as you twist the throttle. I pulled the vacume advance and it seems to be working properly. Any one have any ideas about this. Thanks. Dustin

[kevxs]

maybe you need to swap the vacuum lines that go to the #2 carb boot / carb? I had a bad knock in the bottom left of my engine, turned out to be a simple fix.

[DRedel]

Well the knock was piston rattle. The motor swap was all for nothing. Back to square one. Thanks too everyone who tried to help.