Carb piston not moving

[egonski]

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

[skinnydog0_0]

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

[egonski]

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

[dobbslc]

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.

[egonski]

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.

[dobbslc]