SOHC.co.uk Forums > CB750
CB750 F2
blackeagles:
--- Quote from: royhall on July 15, 2020, 07:36:37 AM ---There should be a non return valve in the accelerator pump body (the removable cap) that prevents fuel flow until the diaphragm is pumped, could that possibly be stuck slightly open. They are still available from CMS. https://www.cmsnl.com/honda-cb750f2-super-sport-england_model14689/diaphragm-pump_16021393004/#.Xw6z8puSmUl
There are no restrictors as such in mine just small bore brass tubes inside rubber tubes (I assume to prevent the rubber tubes collapsing). There's a small air vent in the side of the carb bodies, if one or more is blocked it's impossible to get even running. The vent is hard to see and cannot be cleaned with carbs assembled. Also, I have never seen that vent mentioned in any manual.
My F2 runs spot on after the second carb rebuild to clean the vents, where previously it would not balance up at all. And don't forget, the air screws work in the opposite direction to earlier 750's.
--- End quote ---
as far as i can see the acc. pump non return valve is ok.
you say "just small bore brass tubes inside rubber tubes" if you are talking about the 3 rubber tubes connecting the acc. pump supply to each carb then i don't have any of these bass tubes in my rubber tubes and these may be the 'parts' i saw mentioned. they do not show in any diagrams i have seen - are they likely to allow too much fuel into the carb each time the acc.pump works??
royhall:
I think they are just there to cut down the amount of fuel held in the pipes and stop the pipe collapsing. The diaphragm will only pump it's volume whatever the setup.
blackeagles:
ah, i should have known that!
royhall:
Correction, stops the pipes expanding under diaphragm pressure not contracting. Senior moment.
blackeagles:
it comes to us all!!
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version