1978 390 CR Mikuni Jetting

I am restoring a 1978 390 CR and need help with jetting. I am in California and will be riding between 1000-3000 feet. Any help would be appreciated, I really don't want to seize a new top end! Thanks for your help....

If you are 100% stock (air filter, carb, pipe, not leaks in carb or airbox boot) then start out with the OEM jetting (see parts diagrams or manual). At 1-3K feet, your altitude should not play much of a factor if you start with stock. As long as you are not in extreme heat or cold, you should be able to get it crisp by adjusting the airscrew using stock jetting. Read up on carb tuning theory as well.

Thanks for your help and advice.
I will start with: 430 main jet, 45 pilot jet, Q-8 needle jet, 6DH3 needle, 2.0-2.5 slide, 2.0 air jet. Any concerns from anyone with 1978 390CR experience?

What mix ratio? What 2t oil?

I plan on using maxima castor 927 2t oil at a 20:1 stock ratio. (Castiron sleeves, air cooled)

Less gas in the mix more power, more oil in the case.

I plan to use Maxima K2 at 40:1.......

that jetting should be good enough to get going. as the bike runs in, you may need to lean off the needle clip or drop the pilot and or go up on the main if it needs more juice.

Just finished my 78 390 OR rebuild/resto. I'm starting with stock settings also. Running K2 at 32-1 to start out. Will compare notes with you when I get my bike to the track for the first time, hopefully next week. My tracks will be 2000-3000 feet above sea level.