Snowmobile Repair: 1975 olympic 340, comet clutch, psi pipes

Question
i have a 1975 olympic in almost perfect condition...starts every time one pull...-40 starts in one pull...but she is only a 340 with something like 35 maybe 40hp....could u direct me or help me in finding plans on how to soup up ur ski-doo....or some advice on how to get some more power out of it. i have a friend that says he can kick 120 hp out of her. he is master macantic...he owns 2 sled of his own. i would really love some help if u can spair a few mins

Answer
Hello Bryan,

 That's a nice vintage sled to have. I have never tried souping up a vintage machine, but alot of people do, with good success. Besides things like Split-Fire plugs, a Comet clutch, and different exhaust, you would need to do things like bigger carburetors, over-boring the engine, and shaving the heads. Porting all also helps. PSI pipes are one thing that can make a huge difference but are costly. The Tillotson ( that is what most 73's have) carb on the sled right now, is far from a performance carburetor. If you were to remove it, and either put a larger Mikuni VM carb on it, which are cheap and plentiful on Ebay. Or, you could take the manifold off too, and install 2 Mikuni VM carbs using rubber carb flanges bolted directly to the cylinders. Of course, when you begin to change a sled from OEM to performance, it ends with alot of time tuning the sled to get the right results. Hope this helps. Let me know if you have any other questions. Good luck with the sled! --Arcticatman