1990 indy 500 vs  1990 ski-doo formula mx 470

If you  really want to smoke them even worse i would suggest that you by a polaris light blue spring for the primary clutch install it with a set of 49.5 or 50 gram weights and install a EPI yello secondary spring with a 42/36  helix with a new polaris belt also use a 19/39 gear setting and if possible try a 20/39  if she wind out to fast in 660 if she can pull it to make rpms which is 7800 plus 200 or  200 less and if she can't pull it put a 40/36 in her gut the air box jet up one size and make sure you have good hook up i way 175 pounds and just have fun with them i raced a 2000 ZL 500 and i can take it  not by much but if i can get him of the line i got him in 660 the same with those formula 500 skidoos 470 vmax 500 exciters570 and a few mxz 440 no problem so try this and if you can spare it by a aaen single pipe i also bet xlt's and a vmax 600 with twin pipes in 660 hard to belive but i did well hope this helps you.

you guys who think those sleds can take the little indy must have short memories or just did'nt know? when the 488cc fuji came out in 89, every one was taken by surprise because of its owsome performance and every manufacturer has been trying to match it's performance. 91 to 95 mph top speed. the sd's have a better hole shot but the indy is faster, period. I own a 99 rmk and put a 2'' track on it and tuned it for better fuel mileage and a slite hp gain. it has 34mm carbs and it has such an incredible hole shot and mid range pull, I almost beat a 98 mxz440 to 500 feet. the newer 488 fuji with 38mm flat slid carbs and stronger crank with larger bearings is just plane awsome. it will be faster than mine because it's lighter and has even more power than mine. ps, you don't need to go crazy with all kinds of mods to make it faster. just get yourself a clutch kit from EPI performance and you wont believe the boost in performance.