Hey guys
New guy here. I recently bought a 1981 CB750K. 100% stock except for a goofy sissy bar that needs to come off. This is my first 4 cylinder bike. It's in very good condition with 18k miles. On the ride home, I noticed it wouldn't spin past 5500rpm, so I threw some new plugs in it, adjusted the timing chains, and checked the valves (which were all spot on). Boy what a difference! The bike ran great!
A couple days and tank of gas later, I noticed fuel puking out the #4 overflow hose, so I rebuilt the carbs using the MacGregor DOHC carb rebuild guide. Bench synced them, and put the back on the bike. One of my boots between the air box and carb suffered a small tear, but it's not huge. The bike immediately fired right up on choke, but needed the idle screw turned in a turn or two to idle off choke. She was running very, very well, but I noticed some pops intermittently coming from the exhaust.
A few days later, I synced the carbs using the Motion Pro sync tool. I got them to flat line on all 4. Couldn't line up better.
Well.... now the bike runs much worse than it did before I synced them on the bike. I don't understand. The pops are much more noticeable, and it has some surging going on at part throttle cruising speed.
So what's going on here guys? Anybody ever experience anything like this before?