This is what I'm running in my 95 SS 670 for a set up . the motor is trail ported , has a shaved head , carbs bored to 42's, 3.5 ufo's, 410 mains, 17.5 pilots, 7edy1 needle,AA-3 neeedle jet, 4th clip pos. , 77/148 RV timing with KN air filters . I'm also running the stock single pipe. I gave this set up a beating last year with no engine problems. It also helps to use EGT's but Iknow it still won't save your motor if it's on the cutting edge. I'm also setting my 98 up with UFO's and twin pipes but won't know the final set up till this winter. Hope this might help anybody trying out UFO's! :devil:

Thanks for the post. Good info is hard to come by.

rotax 670

Did you drill out the needle jets with a #50 or 55 drill or increase the size of the hole
in the ufo to 5/16". Is your idle very rich with your setup?

[COLOR=purple]Verm I drilled out the centers with a 5/16ths . The single pipe idles very good . The twin piped sled is going to take some testing. Right now on the jack stand it is fairly close . That sled has the same work done with a few changes . The pilots are 25's with 3.0 UFO's . It takes more time to idle down ,so thats why I think it needs more attention. I use Amsoil syn. so going by piston wash is tuff . Hope this little info helps out. :D