Z440 speeD?
lol hey buddy.i own a z440lx myself.you can very your speeds depending on what you use it for.if you want performance options please email me man.I do my own work and ive known snowmobile engines off the top of my head.I learned from working on airplane engines i get from the junk yard.stock the sled would barely go 75 on good conditions.but my z440 bouncings on loose snow and flys past stock 600s like a fly racing a slug.i tiped my speedometer on my 440.
helpful tip is your clutch and exhaust.
lower clutch engagement sping to 3000rpm engagement
gut the silencer
use sunoco 94 octane fuel and premix 100:1 with synthetic oil
use only sythetic oil in injector.I prefer legend ZX-2r ultra premium
but ski-doo full synthetic is just as good
stock the z440 definately will not exceed 80mph
i bought my 2005 and currently hases 2000 miles on it.THE SLEDS A BLAST BUDDY!