Hello, I was wondering what jet Is reccomended for the Carb at 5200ft elevation (Colorado). Thank you for your help (1970 dt1 250) 

I would give one of the motorcycle shops there a call to confirm what they use locally. I'm certain the Yamaha dealer or locals have figured this out.

If not, maybe test first, then drop 1 jet at a time till you get it where you want it.

Alright thanks!

How much riding are you doing at that elevation? For what it's worth, my '72 CT2 is stock jetting and not fouling plugs or running bad from 3,500' where I live, up to 6,000' on a regular basis and still running okay at 7,500' on occasion, though it does feel the lack of horsepower due to elevation. Not that it had all that much to start with

I plan to ride every weekend preferably, Im trying to sort out the other issue that the bike doesnt rev over 5k rpms. I dont really know why, Ive checked the carb and its almost like new inside. Any Ideas?