too lean on fuel or timing off
YZF 450 puts out 39 hp stock.
Stock 39 hp.
Stock gearing out of crate approx 72 mph
With stock gearing it will be in the 88 - 92 mph range.
the yfz 450 is not that fastest quad, Its not far from the top but raptors have more top speed. there is no 250 that will stand up to a yfz 450 stock
how do you know if your yamaha atv is a 400 or a 450
well it depends if they are both stock or not, if they are both stock, a banshee would probably beat the 450 in top end.
They can be geared to run 100 mph but a stock 450 shoud be 90 to mid 90's.
the fastest stock 450 ATV is the ds 450 by can-am.
if it is a Yamaha wolverine 450 it will go 61mph
YFZ 450 has 39hp
id say 450...