Could be. I'd check electrical first though it's easier. How does the plug look? I think it's unlikely that you have one carb suddenly not working right. They don't lose synch like that as far as I know.
Start with a plug check, then check your wires and coils, then your electronics. All you need is a ohmmeter/voltmeter.
no actually i had to start the bike a few days. the plug was dry with a bit of grey. i installed a Unifilter replacement because the stock filter was OFF... I took the bike for a spin a couple hours ago and run like a dream WTF?????????????
Sometimes the stock coils, when old, can develop a frustrating fault. A crack in one of the windings can exist, but when cool, the contact is still made. Once the engine heats up, like a thermostat, the expansion of the coil and its windings can cause the cracked winding ends to pull apart, with the resulting FUCKING frustration of cylinders cutting out....grrrrrrr.
In other words, you can have spark when cold, or just started, but it can go away once the beastie warms up and shits itself.
Unless he had a freak piece of crud screwing up his carb (float needle or jets) and it decided to dislodge itself and clear up. If it doesn't happen again that's what I'd think. How bout a trying a coil check while they're hot?
Good luck. Hope you fix the prob
it's just a catch can for the tank evaporations saw it on the Yoshi races but and i had to have it for the "cool" factor i went to the container store and got one for $1.50 plus clear tubing from Homedepot...