I've got a '99 Pegaso 650 which has been sitting idle for about 7 years. The carbs were quite bad shape when I got it.
The first time I cleaned the carbs I was able to get the bike started but it was running really rough, so I cleaned the carbs again using aerosol cleaner and compressed air.
I can get the bike running for a second or two if I spray aerostart down the throat of the carbs, but the engine quickly dies after this. There is plenty of clean fuel in the float bowls, and when I remove the carbs there is traces of fuel in the intake manifolds.
What do you think might be wrong?