05 750 issue after riding about 20 minutes

[Mr hadwick]

Ok so I have a 2005 750 with around 33k miles. I’ve developed an issue that I can’t quite figure out. The bike runs normally for about 20-30 minutes and it don’t matter if I’m putting around or if I’m ringing it for all it’s worth. After about 20 minutes I develop a rough idle, hesitation at low RPM and part throttle (feels like a misfire) but if I go WOT it will run out to redline almost normally with almost normal power. At idle the rpm’s drop and it will stall. Choking don’t help, changing from run to prime on the petcock don’t help. It’s almost like this is happening only when it’s warmed up… what am I missing????

all that and I’ll explain what I’ve done so far. Cleaned and rebuilt my carbs (with a carb kit), all new jets, synced them with a vac gauge, re set float height because it almost feels like it’s fuel starving, new petcock from Suzuki, new fuel line, and filter, new CDI box, new coils and wires, I’ve had the carbs off and apart no less than 20 times in the last couple months… what am I missing? I rode 5 miles to work tonight and you can’t tell anything is wrong and I’m sure it will be the same way whe I leave in the morning…

[TonyKZ1]

This may or may not have anything what so ever to do with the problem. But I have heard of something like this before, the issue was caused by a clogged gas cap or gas tank vent. One way to check it, is when this happens, is to open the fuel tank so it can vent. Kinda hard to do while you're riding the bike understandably. Maybe test this theory by leaving it open while carefully riding it?