Suzuki S40 Boulevard Repair

So, recently my fiancé's 2005 S40 Boulevard (pretty much the same engine and setup as the LS650 Savage) has been running really poorly. The engine didn't start or run unless you open the throttle at least 10% or so (choke position didn't seem to matter at all). Once it's running, you had to keep the throttle open or it just quit. On the road at highway speeds, it ran fine, but if you let off the throttle it jerked on/off intermittently until you opened the throttle again.

First thing I did was see if the carb was getting fuel by pulling the fuel line and checking flow in RUN, PRIME, and RESERVE modes. I created a vacuum in RUN and RESERVE mode by sucking on the vacuum hose - everything seemed in order.

Next I pulled the spark plug, which was very black - indicating rich running. I put in a new one, ran up and down the highway about 1/2 hour and pulled it and it was also very black. I took the air filter in/out and that had no effect; the filter looked real clean anyway.

So I removed the carb, all rubber and jets removed, soaked 24hrs then blew clean with compressed air and reassembled: No effect, same terrible running. No ports/jets appears blocked, no rubber parts appeared damaged. Floats did not have fluid in them. In fact, the carb looked pretty much perfect BEFORE i cleaned it, only a very limited amount of stains from old gas etc.

So I was stumped and posted around the internet hunting for solutions. Someone suggested adjusting the valves, which I did. They were only barely out of spec, and the engine still ran horribly afterwards.

It was when I was putting the bike back together after the valve adjustment that I stumbled into the real problem - the petcock. Yep, the first thing I checked...turns out there is a metal part that goes through the diaphragm which had snapped in half, as in the photo. Gas was leaking through, and richening the mixture as it was sucked down the vacuum line. Not sure why I didn't notice this at first....

Suzuki won't sell just the replacement diaphragm/valve combo - only the entire petcock (for $70). So I repaired the item with some wire and gas-tank epoxy.

First I drilled out the middle of the two broken parts, as shown. I fitted the piece of wire as a reinforcement to the epoxy, then assembled the whole thing in a vise and let it dry.

I've been riding now for two days - no more running problems. So it's just a matter of how tough the repair turns out to be...