Motorcycle Repair: Dent in Exhaust Pipe, vacuum leaks, effect questions

Question
Hello Dan

I need to know where to start just to eliminate some of the easier repairs.

What’s not good:
About 4 months ago a purchased a 1982 Suzuki 450T. I took a spill on my first time out and now the left exhaust pipe has a dent about 6 inches from the gasket going horizontal, it didn’t puncture but indents about 1/10 of the pipes diameter. In addition, the same exhaust pipe also has a little hole from rust. The spark plug is a sooty black on that same side. And after replacement turns black in about 5 miles. The bike idles fine, and runs ok up to ½ throttle. Beyond this the bike will have little to no acceleration but when I pull in the clutch  with the throttle still open it will rev up to 11,000+ rpm. When I adjust the air/ fuel idle screw for the left carb it does absolutely nothing.

What I have done:
I have replace the gas, Checked the compression, had the carbs synchronized and cleaned replace the entire right carb with OEM, replaced the left carb needle, pilot, and main jet with different combinations from other used carbs. By removing a spark plug and leaving one on I found that the left one will accelerate fine under no load but will stall when I open the choke. By doing the same thing to the right side I found that this side will bog, and when I open up the throttle it will stall until it warms up, also opening the choke causes the rpm to increase and the bogging to disappear on that side. In both cases adjusting the air/fuel idle screw has no effect. I have switched the needle, pilot, and main jets around but this has no effect.I have sprayed the outside with starter fluid to check for vacuum leaks but this has no effect.

Questions:
The exhaust is going to be a bit costly and checking the valves is something I would need to study up on. Should I continue fooling around with these carbs or should I begin to delve deeper into the machine? Also what’s the effect of having exhaust pipes as opposed to just an open engine (This is just a theoretical question I would really like to eliminate the exhaust but I just don’t know that much about it)?

Sorry for the mind puzzle,
Dan


Answer
Hi dan,
      Well there is goods news and bad.Trying to adjust the carbs with a smashed pie is going to do just what you say it is going to do(too much resctions on exhaust)The open engine theory..does that mean no exhaust at all on no mufflers?Either way it is NO GOOD.I would start by replacing the exhaust used you willl save money here is a web site that can help you-www.thegsresource.com,And here is a page that will give you the specs that you need. www.motorcyclespecs.com, i am glad that i could help,dan