Topic: 750 K8 Accel Pump Question

[brewsky]

In process of re-jetting and found the accel pump clogged up on #1 carb, so I took it apart for a look see.

Looks to me like the diaphram is supposed to have another hole in it but maybe I'm missing something?

If not, then how does the fuel get from the carb bowl to the bottom of the pump bowl?

[CB750F2]

Yes, there should be a hole in both of the diaphragm ears. Also, while you have the accelerator pump apart check that the two check valves are operating correctly. There is one in the bottom of the accerator pump bowel and one in the carb body. They can be seen in your first photo. Check that the accelerator pump is working correctly by mounting the carbs onto a frame, rigging up a temporary fuel supply and operating the throttle. You should see a squirt of fuel from each nozzle with each brisk operation of the throttle. Check the float levels while you have this setup as well. There are a number of posts describing how this is done. Pat

[cookindaddy]

+1

I had wondered the same thing after looking at a new one I had received (not genuine Honda) and finding that one of the two holes was not perforated through, like yours.

Good advice also about checking the check valves and how to do it.

Isn't the accel pump in #2?

[brewsky]

Thanks for the replies!

Yep, the actual pump is in carb #2.

I checked the pump before removing the carbs and got no flow thru any of the 4 nozzles.

Removed the carbs and bowls, and blew compressed air thru the pump joint and got air thru 2, 3, and 4 nozzles, but # 1 was plugged solid.....so I had 2 different problems......the pump wasn't working at all, and even if it was it wouldn't feed thru #1 which was stopped up.

That's when I noticed the lack of the 2nd hole in the diaphram.

Took the pump apart and cleaned some gunk out and both check valves appear to be working, even though it seems to take a fair amount of pressure to open them (by mouth)

Got the valves and nozzle lines soaking in SeaFoam now, so will see how everything cleans up in the morning.

I did manage to get the #1 nozzle opened up with a syringe.