Motorcycle Repair: vacuum leak, suzuki gs 500, vacuum leaks

Question
I have read the postings on vacuum leaks. I have a 2002 Suzuki GS 500 that when ridden for a period of time over revs when clutch is disengaged at a stop light. The Tac climbs to around 3500 RPM. When I pull the vacuum line from the frame mounted petcock the revs drop back to about 1200 RPM. When I plug the vacuum line with my thumb the revs start to climb again. Do you think there may be a problem with the petcock or do you think it is the carbs?

Answer
evidently dennis it seems like you have a faulty petcock ,i have seen this before in myshop.thats causes this problem.try putting something in the place of the petcock like a vacum hose adapter whre you connect 2 hoses togethr ,let me know .im here to help.bud.

mitch