390 surging

i have a 79/80 390 or.engine is a 1980.when riding it hard ,after a while it seems to be surging.idles very high and kind of pings.did not seem to notice this when just cruising the bike.i dont have too much experience riding air cooled bikes and am not sure exactly what normal is???i am using 91 octane fuel mixed 32 to 1 with blendzall and am using some blendzall octane booser.is some race fuel needed?do you think i am lean?dan

Assuming the engine's been leak/pressure tested (I learned the hard way and chased jetting issues forever). Also check the 2 bolts for the head as they generally strip out & cause seating problems (and leaks).

It also assumes the interior of the carb is clean and not worn, the brass is good and the float level is in spec (see Mikuni manual elsewhere on this site)

been loking into jetting this old bike and was curious what jetting should be for about 2000 foot above sea level and 55- 60 degrees.noticed the needle was set at full lean.how normal is that?dan

Surging and high idle is usually a lean condition.

Like lefty said do a leak down test to make sure that you are not sucking air somewhere, then address the jetting
What jets sizes are you running?
What needle and neddle jet are you running?
I am assuming that you are running a Mikuni VM 38 mm round slide correct?

Air leaks suck

Dan, couple things to check, first, the 76 to 83 are known for sucking air in the intake spigut.
check for loose bolts, and small cracks, {very common} they also warp easy, replace the intake sigut, and she should be ready to go.
if you need an intake, shoot an email or call me..
also check for craked reeds and a reed cage housing.