The problem:
http://www.youtube.com/watch?v=HHwymO7OOVA

Don't listen to Bill there are some preliminary steps that you should first make and Seafoam isn't a carb cleaning I don't care what anyone says.

First off try running the bike on Prime to rule out the petcock.   Also have you checked your air filter?  could be almost plugged and that could be causing the bog down.  Those are the first two things I would try.  Also check your vacuum line for cracks or just replace it.  

I had it on Prime when I made the video. The problem is worse in the On or Reserve positions, meaning it wants to stall out if I give it even a little gas. The vacuum line looks OK, and I blew out the air filter a couple weeks ago, though I'll look at that again.
One other potentially relevant detail: I've always felt a very subtle inconsistency in the engine at cruising speed (60mph). Not a loss of power, but just a twinge of not being 100 percent at all times. After having this recent problem I thought that might have been indicating the spark plug was misfiring, but changing the spark plug didn't fix my problem.

Sea Foam

There is a screen in the fuel tank. You might check for free fuel flow. With the petcock in ON or RES, pull the fuel line off the carburetor. No fuel should flow, other than a few drops in the line. Holding the fuel line where spilled fuel won't be a problem, such as pointing into a can, turn the petcock to PRIme. Fuel should flow freely. If it doesn't, the problem is upstream from the carb. If it does, turn the petcock back to ON and reinstall the fuel line. Open the drain in the bottom of the carburetor, holding a container under it so you can catch and examine whatever comes out. You should get a few ounces of fuel as the bowl drains. If you get water, turn the petcock back to PRIme and let it flow until you get clean gas out the carb drain. If you get dirt or rust, you might as well take the carb off and clean it, because nothing will dissolve dirt. You will also need to clean out the tank, because the dirt/rust didn't get generated in the carburetor. Cleaning the carburetor without cleaning the tank will be an exercise in futility. Adding an in-line filter will keep the dirt out of the carb, but it will plug up itself instead. By the way, there is supposed to be a filter in the carburetor inlet, too.

Routy wrote on 08/26/10 at 18:07:56:


I still would try and start the bike with the air filter out of it by the sounds of the video the bike was either losing a vacuum or starving for air I'm betting on the air filter mine did almost the same thing when I first got it.   I have no problem with Seafoam and use it all the time and I was just joking with Bill but stand by what I said.  

Another thing nobody has suggested ...  Have you changed the gas in the tank?   Old gas can really make you think you have a carb problem.

Some good replies here, as usual....

I'd try all of the easy stuff first.  Then, if still no joy, try putting in a new spark plug before you get into the carb....you might just get lucky!

Good luck!