Running rough at high RPM's

I've looked though a few pages of the forum and haven't seen this problem. That doesn't mean it's not there, if it is I didn't see it. First of all, I bought a 1981 Maxim 650 a few years ago. It only had 7,500 miles and was in pretty good shape. It had a cracked pipe, but that was easily replaced. I didn't run it for about a year (Kids, life, etc), and when I did go to revive it, somehow the petcock was left in the Prime position. I changed the oil and couldn't get it to start. I did a carb clean, not like what's described in the forum, but I did find alot of junk and clean them up. Finally got it to start after replacing the plugs, but it had no power. I took the carbs apart again and did a little job of cleaning and it runs very nice at low idle. When I drive the thing, at 5,000 to 5,500 rpm the bike starts popping and losing power in 2nd gear. In 3rd gear it starts popping at around 4,000 rpm. I'm guessing I need to redo the carbs right and sync the engine? Any thoughts would be greatly appreciated. By the way, I found this site last week and can't believe all the info! Thanks!

 

Hi Dewman, welcome.
I am thinking float levels, or more likely petcock, try running at high revs on prime.

 

I can't get the bike to start now. I guess I'll order the parts and do the carbs right. Thanks for the advise.