How important are RPM's for TPS adjustment?

[Slow and Jerky]

I need to adjust the TPS on my son's 03 YZ450. Manual indicates that the engine RPM needs to be 1,900 - 2,100 rpm. At the moment I don't have have an inductive tachometer, so the question is how important is it to be spot on or can I get it close by ear?

Also, since I really should buy a tach, anyone have a recommendation? Since this doesn't really have a traditional plug wire I am little confused as to what I should be looking for.....? ?

[grayracer513]

An inductive tach would need to have a trigger wire that could be wound around the high tension source. You would then wind it two or more turns around the coil (spark plug boot) just blow or above the seal.

2000 rpm is a "high normal" idle speed. Higher than a slow idle, but not really a fast idle, either. probably about what you normally idle at in most cases.

[Slow and Jerky]

Thanks !