PO cut my pipes, back pressure issue? Bent valve risk?

[Meet The Twins]

I recently started my 76 CB500T for the first time in years and Im getting a real nasty Idle. I figured a carb clening would do it but no luck.

As you can tell from the clip its a werid idle. I wasn't touching the throttle that was all the bike reving itself. One of cylinders is fine, the left side is the one with the erratic idle. I doubt its a back pressure issue seeing as both pipes are cut evenly but I wanted to make sure.

Do you guys think Im running the risk of a bent valve with poor back pressure?

Thanks!

http://media.putfile.com/CB500T-Exha...time-start-up-

[telefunkin]

404 not found on that clip

[dr_bar]

404 not found on that clip

That would be because the url is incomplete...

[Sev]

By the time your pipes are as long as you've cut them back too it shouldn't matter too much. It's not totally a backpressure problem. You're going to need a rejet though, I'd also check the carb boots for leaks, and make sure that I actually cleaned and set the float heights on the carbs correctly.

I think the most likely culprit is a vacuum leak.