The highest gear used in AMA Supercross?

4th gear is used in the whoops.  No need for 5th unless at the old Vegas stadium

They used to remove the gears and replace them with plastic gears to save weight ,back years ago.  At the time ( not sure if the rule is the same now or not) The race bikes had to have the same number of gears as the production bikes. So they would make light weight gears that could never really be used.  Sometimes it was 1  of the speeds , but I heard of some bikes having 3 speeds that could be used and fake gears for the rest.

Probably not anymore with the 9 whoop jumpers this year 

I am pretty sure last year I saw a post from someone who did the Star Yamaha VIP thing at a race and one of the pics they posted was of engines, and I feel like one of them had a tag on it that said Tomac and indicated it had 3 gears.

I thought that the rule book said that all the gears had to be in place? 

The YZ400M that Doug Henry rode to victory at the sun baked 1998 Las Vegas SX was apparently a 2 speed transmission.

https://m.youtube.com/shorts/e_FWiOTFujc

I’d say atleast 5th unless the track has a super fast straight going out of the stadium like Sam Boyd always had.  Tomac triple up shift before the whoops 

2.4.3 TRANSMISSIONS AND PRIMARY DRIVE
a. Motorcycles are restricted to the use of rear-wheel drive only.
b. Primary drive method must remain the same as the homologated model.
c. Primary drive must be completely enclosed by a cover or guard.
d. The maximum number of speeds in the gearbox is six.
e. Number of transmission gears must be the same as the homologated model.

Didn't one of the early yz450f come as a four speed? 

cocaine?

The early rmz 450s did and I freaking loved it 

Top 250 guys use 5th

I believe that is correct but it doesn’t say anything about changing the ratio. 

2003-2005

I have that photo but ML personally told me someone didn’t want it on here and it would be removed if he saw it again 

I’d imagine 3rd is normally the highest used for the most part. Didnt McGrath use 1st and 2nd in the 2 stroke days?

I’m not in the know as much as I used to, so this could be wrong now. 
 

 Several factory 250s use 3 speeds, one factory Yamaha had a 2 speed. 
 

 The majority of 450s have 3 speeds, the rest are 4. Some guys use 4th gear to avoid wheel spin in the woops. 

2005-2006 RMZ450s were four speed, and same as you, I loved it! 
 

loved it more than the 09 5 speed I had. 
 

the YZ450 2003 was 4 speed. I hated that bike.

I think I read in an old MXA or Transworld that Red Dogs Factory Yamahas were 3 speeds

250s are pretty much all five speeds now and multiple riders use fifth in the whoops, McAdoo being one note-able one.

450s are four or five speeds. Haven't heard of anyone using a three-speed for a bit now.