If that RMZ is hard to start check the valves, run them on the looser side of the tolerance. Just a thought, thats what I do on my Husky and it likes it better, Exhaust spec is b/t 0.006-0.008, I run them at 0.008. intake is 0.004-0.006, I run them at 0.006. They tighten as they wear, Also run leaded Sunoco 112 Premium for a little led lapping. But hey, it's what "I" do, you can do what "you" want with "your" bikes.
I was told the bike just had a rebuild last summer and the valves where just put in spec before they put it up for sale. They had several bikes and a private track etc etc bla, bla bla but I had no reason not to believe them since they said they don't work on their bikes they let the shop do all of their maintenance, cough cough @Rack all of their bikes look to very well kept and this bike was completely spotless. It was just a spare bike not needed anymore hence the sale. They had more money than they knew what to do with, which is why I thought they weren't lying about the shop and why I thought of @Rack again
anyway it may be the fact that it was all BS but again I only had it out once. It will fire up first or second kick cold and runs like a scalded dog just don't kill it. I pop start it right back up just kicking it is a mofo.

but there were 6 bikes in the room all but one were RMZ's and only three riders to ride them all and only two 250's, this bike was one them and the oldest bike being a 2008. the other 250 was 2010. the other 450's were 2013's and only one was a yz450 poop. Did I mention they kept them all in the basement all lined up like a show room in a monster log cabin sitting on 230 acres with a private track. Just didn't see any reason why they would lie about it.

