I have a 1997 Skidoo Formula SL 500cc fan cooled sled and need any sort of extra HP I can get any suggestions?

You will not find any aftermarket hp parts for fanners. Your best bet is to ride this one and save up for a liquid cooled sled.

you have a couple of options. have a smaller top pulley made for your fan belt, new belt and make it spin faster. remove heads and squish them to .050 inch and always use premium fuel, while the heads are off get them acid tanked and then milled to the .050, and make sure you don't get them painted or anything after that. they will dissipate heat better that way, and if you want, go for some clutching and gearing, and your 500 will do well. the squish will up your comp by alot and give you some good snap.

I have this same sled, and have wanted to do something else. Everybody tells me just drive it and leave it alone.

So, I did. But I did check the basics like timing, engine speed (clutching), and spark.

1. Timing was out just a little. Its a pain to do because of the air shroud and you need a dial indicator. Also the timing mark is a little weird how its situated, Further when you loosen the nuts holding the trigger, the thing moves toward the magnets on the fly wheel, and therefore you will have to reset the airgap. But it is worthwhile if its not correct.

2. There is a sweet spot on this engine. You will need to spend some time in this department, but again its worth it. I slowed it right down to 7000 RPM. 7200 was too high and 6800 too low. The 'clickers" didn't do it, but changing the weight did.

3. By adjusting the air gap to stock and using NGK Iridium plugs the result again was worth it. Before I started any of this, it was a bear to start. You had to really fling the engine over if you wanted any chance to start it. Now both our daughter and wife can start it.

So how much difference did this make, I went from barely 60 MPH machine to 74.4 MPH on radar last year. It is way snappier out of the hole and will easily spin the track. My daughter thinks that is important.

Overall I would say its a good machine, I don't mind riding it, primary is a '02 MXZ 700 and awaiting the '05 Mach "Z". But with this improvement its a keeper.

Hope it helps.