rd carb tuning

[daves1977rd]

My 1977 Rd.400 bogs  at hi rpms. above 7000 in 5th gear.Have 27.5 pilot jet 200 mains.air screws 1.5 out.plugs a mediun brown.this when I open the throttle completely!If i back off a little it runs again. Is it rich on the main jets?Should I try the air screws at 1.75 or 2.0?Oh yea stock porting, compression Tomey y boot air cleaner. thank you all. 

[m in sc]

always err rich. stuff 220s in it see if it gets better. if it gets worse, go back down to 190s. If that doesn't do it...
 i had the same issue on my hybrid, as soon as i clicked into 6th wot.. turned out the bowls were getting sucked dry, had to go to a bigger needle and seat. if you have 2.0 needle and seats, jump up to a 2.5 or a 3.0. & check the petcock flow. if you are runnign fuel filters, make sure they arent restrictive. the brass insert ones are choke points.