I bought my 749 Airwaves Rep last year which had been laid up for 4 years as it was not used by the former owner. Anyway i took it for a blast last week and when i went hard on the throttle in 4th the bike spluttered and then cleared, symptoms were as if was running out of fuel, i looked in the fuel tank and it was cloudy. I ran it low and necked it with fresh fuel and bike ran great, washed the bike and stuck it the garage. Few days later went for a run and it ran like shit again, checked the fuel and again it was cloudy. Left it to sit for a few hours the fuel was clear, start bike upo and i could see the fuel clouding up. I noticed some white powdery coating on the inners of the tank and think this may be the cause and maybe after the 4 years of being laid up the fuel went to crap and left this white coating. Any one seen this before.
I'd suggest there's two options, either there is air in the fuel due to a split pipe or leaky connector or there's water in the fuel. When you can see it's turned cloudy, turn it off for a minute, if the fuel at the top of the tank clears first it's water. The white coating isn't from the fuel its from moisture but as it's been sitting for a while this might not indicate anything.
It's water then, you really need to take the tank off and empty everything out it'd be a good idea to change the fuel filter as well. That'll sort the water that's in there, you then need to find out how it's getting in, maybe the fuel cap probably isn't sealing and/or is there a drain hole and pipe in the filler neck that may be blocked or come off?
The drain holes were blocked and i fixed that problem as i noticed the water was not draining and presumed that would be the cause, so now i suspect the fuel cap seal. I have the bike booked in for a service at my local dealer and explained the running issues they said they will renew the filter.
Put some grease on the seal, close it then open it, you'll be able to see where the grease has transferred. Also check the drain pipe is connected inside the tank, pour some petrol down the hole and make sure the same amount comes out the bottom. You may have fixed the leak, but you'll never get all the water out of the bottom of the tank without taking it off as some will always sit below the bottom of the pick up. Fuel filter's don't like having any water through them so that could cause problems. I guess the good news is it doesn't seem to be anything nasty .
After you remove and drain the tank, and refit and refill it, add 250 - 300 ml of IPA (Isopropyl Alcohol) to a full tank of fuel, the IPA "converts" the water/moisture to a combustable liquid, then go for a good long run to drain the tank
