Coughing and Sputtering carbed 750

[the_Journeyman]

Ok, so went on a nice ride and out of the blue, riding along at a gentle pace, I got loss of power, backfiring, sputtering and general grumpiness.  I down shifted and kept the revs up and had problems for a couple miles or so.  After that, it smoothed out and ran fine.  It started doing it again when I got home.

What would cause this?

Things that might be important:
1.  I did fill up with gas before we left of the ride, and I've used most of that tank.
2.  The first time it did this, I was up around 4500ft elevation
3.  My fiancée tipped it over in the garage when we were lubing the chain, but didn't hurt anything.
4.  The behavior can best be described as how it acts when you're running out of gas.

Thanks!

JM

[Howie]

I would check the fuel for water and change the fuel filter first. 

[the_Journeyman]

Thanks!

The water (where I had just filled up this morning) was one of my suspicions, so I'll see about that.  I'm on my original filter, so I'll check into one of those ~

JM

[CRASH!]

Could be your fuel pump diaphram. Pull the output hose and crank the engine. If you don't get a strong flow of gas, your fuel pump has gone Tango Uniform. You can rebuild with a Mikuni rebuild kit. $20 from Sudco and a bout $12 from motorcyclecarbs.com last time I was in the market.

[hooligan machinist]

  I'm a bit hesitant to post this because there are so many things that could be the problem. And it is a bit far fetched, but check your floats.
  What you're describing sounds a helluva lot like what mine was doing last summer. I went through the entire fueling and ignition systems several times before finding the problem. One of the float pivot pins had fallen out of one side of the bracket.
  Since you said the bike got tipped over it's a possibility. Mine was due to a lousy mechanic i let do my jet kit. He put the pins in backward.

[jerryz]

definitley change the fuel filter , clogged filters makes Dukes reun like they are weak

[Bizzarrini]

Don't know what the temperature was when you were riding, but maybe vapour lock?

[the_Journeyman]

but maybe vapour lock?

It was in the 80's (fahrenheit).  This could be the case and here's why.  The 1st time it happened was I was suddenly going slower after catching a pack  of cruisers.  The engine heat could have started rising more upward than going rearward.  After I parked it, it was right at 90F and I had just ended my ride and the motor was good and hot.  All that heat rising could have triggered that same behavior.

I'll definantly change the fuel filter.

Didn't someone pick up a cheap alternative at the auto parts store that fit these carbed bikes perfectly recently?

JM

EDIT:  Found the filter alternative, had to go to *gasp* TOB to find it.  Thanks to Duckets if he's on this board.  It's filter number 3047 from Autozone