Carbs on the left side not getting fuel

[98.cr250]

I am having some trouble with my carbs, the two on the left side aren’t getting fuel but the ones on the right are. I have already rebuilt all 4 of them and sprayed them out, when I put them back on I started the bike and only the two cylinders on the right fired up. I have already checked the float bowls on the left and they’re dry. If anyone knows what might be wrong please let me know. Thankyou in advance.

[Rambozo]

The only thing that comes to mind is you have mixed up the fuel lines.

[cfairweather]

It is possible that the the two dry ones have stuck float valves, in the closed position. Can you provide some more information about how you rebuilt the carbs including the method you used to adjust the floats? Did you replace the original float valves using a third party float valves? If so, what brand? Try tapping gently on the carbs using a screw driver to see if you can get the floats to drop down. Then try and crank the bike. It takes at least 30 seconds to a minute of cranking to fill all 4 carbs and they do not fill at the same time.

[cfairweather]

Two other possible reasons:
1. The fuel runs through passages in the plenum. If the carbs were sitting with gasoline in them for years, the fuel passages may be blocked with dried fuel. Did you use an ultrasonic cleaner set to at least 65C?
2. The same issue could exist with the tiny air passages within the carbs. If the carb cannot vent, gasoline would be restricted to enter the carbs. It is very important to get these carbs perfectly clean.