Motorcycle Repair: Fuel starvation on a 1991 Suzuki GS500E, vacuum petcock, fuel starvation

Question
Hi Chris,
I own a 1991 Suzuki GS500E that I've owned since I bought it with 136 miles on it in 1993.
Last summer, on a 400-mile trip, I was riding along the Interstate and it began to lose power and felt like it was running out of gas. The only problem was I had just filled the fuel tank before getting on the highway. I limped the bike home, as it would do this running out of gas routine all the way home.
Since it felt like a fuel starvation problem, I removed and disassembled the fuel tank cap and cleaned out the vent. I then replaced the vacuum petcock (two petcocks on the GS500, one for vacuum and one for fuel).
I'm still not convinced this has fixed it. I seem to run onto reserve faster than I expected, leaving me with worries that the problem is still here.
Any ideas for what else to check?
Otherwise, the bike runs well.
Thanks for your help,
Todd


Answer
Hi Todd.
Let's start with some simple things to look at;

1)  How far did you go before reserve before the problem and how far now?
 If you are talking about a difference of only about 5 miles or so, then the problem was that the fuel lines had problems when you got the bike and only finally came to a head on your trip.

2)  What condition are the plugs in?  Are they more fouled now than they were?
 If so, then the problem could be in the carbs, which does not necessarily mean a mixture adjustment, but more likely means that someting has failed or come loose in carbs, or that they just need a good cleaning.

Start with those and let me know so that we can take it from there.

Good luck.
FALCON