Was having a problem running from cold. Thought I would post the information if it can help others.
Started a ride and from the house I could feel a slight hesitation when coming on to the gas which is not normal. After a half hour riding she started to backfire on decel, which she never does. I should say my bike is an 09 FE570 mapped set to wild with FMF powerbomb and FMF 4.1 can. So I shut her off when meeting up with a friend, she started no problem and we set off. The hesitation was still present and the backfiring got progressively worse.
5 minutes afterwards crossed a 25 foot long puddle on the back wheel but front came down halfway through and soaked the bike and myself really good, hot day so no prob for me but the bike stalled on the other side of the puddle. Had a hard time starting after, finally got it going but needed to keep revs up for it not to stall. The idle was weak an not at all confidence inspiring.
Arrived at destination and shut bike off for 45min-1 hour. She started after a couple tries but again had to keep the revs high. Headed for home to figure out problem. On the way back using the street the bike would bog under acceleration and be jerky and constant throttle. The back firing was really bad by now.
We started by testing the battery and it was losing charge, so new battery... New battery in, big would turn over alot better but would not start. Changed the spark plug for a new one and inspected connectors wires and grounds. Fixed a couple of chaffed wires which have been grounding when wet, unsure. Bike still wouldn't start. Proceeded to take out gas and put fresh gas in with some seafoam cleaner. After 5-10 minutes of letting that sit, still no go.
So off comes the tank. Checked all wires and connections again. Good pressure in the fuel line. No pressure build up in gas tank by the way. Opened gas tank to check fuel filters. Main filter is dark colour, filter beneath pump is clean. Put 12V to pump, it's turning and pumping well. Blew and sucked from other side off filter, one way valve working and mouth full of gas. Checked again good flow from pump at other side of pressure regulator.
At this point put everything back to try starting again. Hit the started button, idles likes an FE570 should. Let her idle 15-20 minutes with new gas and seafoam. Gave her some throttle, no hesitation from idle and no backfiring.
So though I can pin point what the exact fix was or if it will last this is my experience with an ill 570 so far.
I was ready to order CA pump and fuel filter kit but am holding off for now.