I took my track off and put new bogie wheels on. I put the track back on and put it on the jack stand. Once the sled engaged the track started spinning. Once i let off the track stopped very quickly. It seems too tight but it feels like its ratcheting. How do you measure how tight to put your track?Thanks

If it isn't studded, loose is not so bad. As long as it doesn't "ratchet" on the drive cogs, it's fine. Loose is fast, it can buy you 5-6 mph on top.
If you're studded, I'd say 1/2 inch as measured from slide to track @ mid slide rail with 10 pounds of draw.. If you can find a 10 lb weight, hang it from the track.

I usually have 1/2 inch of sag in the middle

Like he said, looser is faster. I have gained 3 mph on radar by just backing off the bolts 1-2 turns. It really is fine to have it loose, try it from a dead stop and see if it ratchets. It will make a god awful sound if it does, you'll know it. then go one or maybe just a half turn tighter, just a whisker at a time, untill it stops. I like my track to want to Creep just a bit with the sled raised on a stand. that is if the sled is idling (raised) it will not turn the track but if you give the track the slightest nudge by hand, (watch your fingers) it will start to move in full revolutions on its own. I check my studs this way before each ride. Just look in beside the flap and watch them come around. If your track is abrupting coming to a halt, it's way to tight. owners manual should have a spec.

Per the 2001 AC manual:

CHECKING DEFLECTION

1. Tip the snowmobile on its side.

2. Hook a spring scale around a track clip at mid-span;
then pull the track down with the scale to 9 kg
(20 lb) and measure the distance between the
bottom of the wear strip and the inside surface of
the track. Track deflection must be within
specifications.

After Break-In Tension
FasTrack w/o Torque sensing = (1-1 1/4 in.)
FasTrack w/Torque Sensing Link = (1 1/2-1 3/4 in.)

If you track is new the specs are a little tigher, I usually run a little looser than spec if possible. Be careful doing this if you have studs.

Sub 10lb instead of 20 and go to the max suggested for loose.

Hey
If you think that the track is to tight and by what you are sayin it does sound to tight. It is probly your chain skipping. Try taking you chain case cover off and look to see if there is a bunch of little lines grooved into your gears then you will know if it is track or chain. But with what you are saying that is your common chain skipping.

chris