What exactly is the main difference between star racing yamaha and the factory Yamaha?

FIM rules are not nearly as strict as the AMA rules.  So the MXGP bikes are a lot tricker and more heavily modified than the Star Yamahas.  I wonder how much technology is shared around the globe between the two though.

Weren’t they using star motors last year or the year before?

The piston on the star bike is made out of unicorn horns

frame, swingarm, traction control.  

Guessing weight and rigidity

Championships....

I read in MXA that the Star bike added a tooth in the rear, as per their recommendation 

Paging Lewis Phillips

Can we get a 450 Shoot Out of the STAR bike and an MXGP Factory Yamaha ?

Whilst you're right about the variation in rules, Id guess there isn't that much difference between them. I dont see the GP team making much in the way of crankcase, frame & swingarm changes these days.

The geometry of these things across the board is pretty much sorted, and the range of adjustable parts such as linkages, suspension, bars & clamps seems to be infinite and they can bolt stuff on to suit each rider. I dont think they're adjusting frames and other bits these days. Back in the 70s, 80, 90s yeah , but not now.

I thought RV said in an interview that with the fuel the GP's allow, the engines felt detuned compared to the AMA spec engines. I could be wrong though.   

I think he also said they run softer suspension over there and it was hard to get use to 

On a side note, what a lame name for a team…”Star Racing” lol.  That’s the best they could come up with?

Because the owner Bobby Reagan owns Star Chevy dealerships across Houston. 

Yep!

Man a much better name would be The Dennis System of Santa Barbara Racing Team....

Eli Tomac

I know from the riders perspective the teams are way more open to making changes. Factory Yamaha wanted factory Yamaha parts on them, Chad and Webb had been critical of how yamaha wouldn’t even allow them to test other parts or stray too far away from how they wanted the bike to be. Star seems like anything is an option because they want to win.

Even worse when you have to listen to RC pronounce the whole name all the time during racing.... 'he looks good on that Monster Energy Star Racing Yamaha'... just say that guy looks good on the bike, we get it... 

Comment written in the https://www.vitalmx.com/forums/motorelated forum

They’re pretty similar this year, they’re running the same bike.

 The GP bike runs factory hard parts and has the option of different chassis characteristics. I don’t know about this bike, but they also have the option of running a true 3 speed gearbox. An older factory 250 had a 3 speed gear box, I don’t know if that’s still available. 
 

 The Star bike has a lot of non factory parts built by other vendors that you won’t hear anything about. I think a different rear brake, and a rekluse clutch. 

When Michael Leib raced the Dixon YZ250F in 2012 it had a three speed transmission and reved to 16,000 rpm. Cosworth developed the valve train, cylinder head, piston and crankshaft. 

I used to enjoy Vital for the intentional humor. These days it's the unintentional humor that keeps me coming back. lol

Its super simple

Management that listens

vs

Management that doesn’t listen and thinks it know everything 

I’ve heard Zach Osborne say to this day that 250f was still the fastest 250 he has ever rode.

from that post a few weeks ago the engine tag on star said 4 speed trans 

Keith McCarty is the difference 

I completely agree that the 2 different sets of rules make it look that way & allow for the scenario you’ve explained; but, in reality…are the MXGP Yamahas any tricker than Star’s?