Hello all, just removed the carbs from my vfr as it was running a bit lumpy and throttle response wasn't what it should be. Before I removed them, I had the air box off and an auxiliary fuel supply hooked up and I could see that as I worked the throttle only three of the carb pistons moved in unison, the fourth, rear right hand carb as you sit on the bike- number 4?, didn't move at all. I nudged it with a plastic rod and it does move so it wasn't jammed, but it just didn't want to work with the others. Now this could be the reason it isn't running great. I have now taken the carbs off and was expecting to be able to replicate the movement of the throttle and see if there was a broken/loose linkage. However, when I move the throttle wheel only the butterfly flaps open and close, no movement from the pistons at all. Is this because the engine isn't running?. I have had it apart and all seems OK, but I have a feeling this is the problem, effectively the bike is running on three. Any help gratefully received!

Ian

Sounds liek your rubber diaphram on that carb may be split. get them off and have a look.

Thought that might be it but they all appear fine, not hard and no splits visible.

Is that the cylinder that operates the fuel tap? Could be a split in the vacuum hose.
Check the diaphragm in the carb top, if it's split it won't lift.

That was the problem, thanks. Turned pipe round, snipped off the chewed up bit and away I go. just got to balance them now and job done.