I 've been having a problem trying to get my engine to idle. Its not that the idle screw is tuned to low or its not getting enough gas or to little. The motor is in perfect shape and runs good when not stopped but Ican not get it to idle over 5-10 sec.

Ihave a O.S. vzb speed .21

Have you tried the pinch test to see how the engine reacts? Its at least a starting point to see where u need to move the needle.

Its hard to diagnose engine tuning issues over the net, but myself and im sure others are willing to try and help

Is it broken in?

If it will not idle longer than 5 to 10 seconds, it is the Low Speed Needle.  Use the pinch test, that is, make a high speed run, stop the car and immediately pinch the fuel line close to the carb.  It should idle up for about 3 seconds then die.  If it takes longer than three seconds, then the LSN is set too rich and you will need to lean it about 1/8 of a turn.  If it dies right away, then the LSN is set too lean and you need to richen it 1/8 of a turn.  After each adjustment make a high speed run to clear any extra fuel out of the car and do the pinch test again until it gets set right.

you have a speed but don't know how to tune it? always start tuning with a new plug and with motor at temps. thats an expensive motor for us to try to help over the web, try to get a local racer to help so they can hear and see the motor. they can also tell you if maybe its a motor issue and maybe not tune, leaky carb, bearing or cracked case, loose head, etc.