my 660 turbo heats up especially on hard packed trails or lakes.
the machine sits high and the snow flies out under the flap instead of up to the cooler.
dealer changed thermostat and said everything was ok.
Some say i don't have enough weight on back of sled.
does anyone know or have any suggesstions on how to lower rear suspension?

Get a standard rear flap (longer) and replace your short one.

A set of "ice scratchers" either mounted on the skis, or on the slide rails, will create more snow spray under the tunnel for cooling.

Also put on a long snow flap, as previously suggested by others. I have done both, and made a huge diffeence. If my pic attachment works, you can see I added 5 inches to the flap, with a piece from a a truck mud flap, and I added two pieces on the sides of the tunnel to help keep snow under there. Looks goofy, but works, and I can't see it when I'm riding. LOL.

You can see the scratcher in the down position. These are a bit too long, I may change them.

Own a 06 ST660 Turbo, have had overheating problems from the start. Dealer as well said it was because of riding conditions(hard packed snow) but my sled has studded track and is creating sufficient snow for the heat exchangers. Friend has same sled(1 year older) and does not have this problem. Comparing both machines on same ride, same conditions friend's machine runs MUCH cooler than mine.
My machine has been back to the dealer 7 - 8 times. They have tried adding longer snow flap, changed theormostat, added a coolent restrictor in the bypass hose of cooling system to allow more main coolent flow to the water pump. Last item was done earlier this month took it for test ride and engine over heated at 14 mile mark.
I believe the problem is that the main cooling system has a major restriction in it causing the water pump to cavitate. Overheating occurs not at idle but at speeds over 20 mph

Make sure your anti freeze mix is 50/50. If the antifreeze is to strong it will overheat.

yes coolent is 50/50 mix. this is engine #2. still have same probblem.

I wonder if they burped the coolant properly, larger air bubbles will not circulate out. Have you had a vacuum bleeder put on the coolant system? Or put the skis on some car ramps, and let it idle with the rad. cap off. I have burped almost a dozen sleds this way and no probs.

ever thought of a different coolant like "engine ice"

yes the cooling system was blead as pre arctic cat instructions. never herd of a vacum bleeder.? & never herd of "engine ice coolent"? i don,t know if my dealer used a vacum bleeder . i will give them a call & check. my dealer is 3.5 hrs away.

3.5 hrs away,theres nobody closer?Engine Ice is mostly used in Motocross,but I double checked for antifreeze properties before I suggested it and its good to -26f.Its supposed to lower temps "up to 50 degrees" their are other brands that say the same but I like the "ice" it seemed to make a difference in my raptor when I had it.

if softning the rear susp is not anuff ,as in backing off the tension on rear spring u might be able to get softer spring ,to stiff is not good a suspension is supposed to work , not beat u up,unless u like beating ditches , everybody is diff good luk!!

I think your last sentence (original post) hit it on the head.
not only will you fix your snow problem, but your ride wiil be so much better!

My 05 T660 the rear end is so stiff (I just got it) it doesn't compress at all with all my weight on the seat.
To loosen the rear suspension, you have to move the rear lower link and stopper bar forward one hole.
Moving this forward changes the angle between lower and upper rear links. Stock, they are about 170 degrees apart.(Often referred to as a knee joint)
By doing the above, the angle will change to about 150-160 degrees, which makes it easier to compress the suspension.
Unless you are jumping it, you don't need it this stiff.
Look at your car/truck.. it weighs 4000-5000 lbs. When you put your 190 lb body in it, the suspension moves. Your body is about 4% of the weight of the vehicle.
Now a sled rides on typically a little rougher than a car.
But with this said, a good suspension set up for mostly smooth and stutter bump riding should be much looser than most people have them set.
Your rear suspension should compress 40%-50% or so when sitting on it.
If you bottom out on a bad bump every 10 miles (on a bad trail) I would say this is setup is right.
Cause then you are using 50-75% of your suspension on normal trails.. 2-5" bumps.

I have to loosen mine. I don't think it compresses more than 2" on 3-6" bumps.. This is a waste of 11" of travel, the way I see it.
I think the front rear shock should be set to almost as loose as it goes!
factories set them up realy stiff, so you don't break the sled on jumps.

I have a 2006 T660 Turbo Trail with much the same heating problems. Tried longer flap, studs, maybe helped but not much, 2 dealer's no help, in saying all liquid cooled having problems on frozen conditions. Even with some loose granular I still overheat unless travelling well over 50 KM/hr, not easy to do all the time on most trails.

I noticed the angle of the lugs on the track seem to point forward when looking from the side at them on the snow. I would think if pointing back would lift and kick more up rather than picking little up like mine does. Reversing the track might help but would be a costly change.

Anyone observe the lug angle - forward or back ?

The reason they do this, is so you can stop better than you can accellerate. If you decide to do this, stopping capabilites will go down. Acceleration (grip) should get better.
Just an FYI... Sometimes having braking capability is under rated.. until you really need it.