Noticable pulseing surge at 4000 rpm on highway

[siscoken]

My 76 has a surge at steady throttle on highway at 4000 rpm ... no wind.... seem in my mind like I have a slide diaphragm fluttering or fluctuating .... anyone experience anything similar.
Bike runs perfectly other than that.

 

[gggGary]

pics of the bike, what carbs, what air filters, what jetting?

 

[gggGary]

what slot are the needles set at have you visually checked diaphragms?
done a slide lift test
compared how the two slides open when revving the engine?
Looked at, compared the plugs?
Checked timing at various RPMs with a timing light getting smooth timing advance?
checked for air leaks at front of carbs (spray carb cleaner while it's running).
synched the carbs?

 

[siscoken]

Full disclosure... when i cleaned carbs... as I had never run the engine... I never logged the carb info that I usually do... Just cleaned and put everything back where it was .... point dwell and timing at idle set right to spec, with timing light... never check monitored advance thru rpm ... Just verified that the centrical was working.
I do have a carb base mount that is damaged but I don't think is leaking... (parts on order).
Check mileage against my dr650 and it is getting a little better.

 

[siscoken]

pics of the bike, what carbs, what air filters, what jetting?

Everything is stock