I have been having plenty of problems with my cbr f3 for the past 2 months. Recently I was flooding the cylinders, and now Im not getting any fuel to the 3rd and 4th cylinder.

What I know-
Plugs are all new and gapped, and Im getting a spark.
Carbs are clean! Every jet is clear and the needle is in position and moves freely.
The little carb valve is in working order, floats slide perfectly and make a seal when closed.
The carbs are visually balanced.
There is nothing blocking the fuel lines.


Even when I pulled off the airbox and shot starter fluid into all 4 of the stacks, the 3rd and 4th carbs did nothing (I know this by feeling the header temperatures)

Any tips or ideas? Also my 4th carb boot doesnt seat completely onto the engine, there is about a 2mm gap but I did tighten the clamp down tight.

 

float height?

 

Uhhh is that even adjustable on our bikes?

 

Did you mess with timing at all?

You say there's a seal issue on #4..are you positive there is no seal issue on #3?

To confirm: You have spark on all 4 plugs, fuel delivery to all 4 cylinders and air delivery to all 4 cylinders?

 

On the subject of timing I did check the valve clearances and all that but have successfully ridden my motorcycle since then and the bike was as powerful as ever.

I have spark on all 4 plugs but I dont think fuel (possibly air?) is getting in there. When I sprayed starter fluid onto the 3rd and 4th carb the bike still ran like it was only firing on half the cylinders, Same story when I sprayed into the ram air intake.. Also after trying to start my bike after a while, I pulled the plugs and they were dry as if they got no fuel at all.

 

Are you sure the floats are not sticking in any way? It sounds like a carb issue still, have you checked that float height is correct?

 

they're lil plastic holders so no on adjustability... Hojen has a good point

 

I am Positive the floats are not sticking, not only did I clean out and polish the hole the valve slides through. I also plugged the vaccum plugs and blew through the fuel line, and then turned the carbs upside down (closing the float) and the valves sealed close and didn't allow me to blow through.

How does one check the float height?

 

What confuses me the most is why the cylinders wont fire even when i spray starting fluid directly into the stacks.

 

what was your method for checking spark across the cylinders?