1977 cb750 carbs

[sfaulk320]

Ok, back again with another question for you awesome fellows. So i tore my 77 carbs apart for a cleaning, i was scared at first since i never worked on a carb before this build, the tear down and rebuild wasnt bad at all, before the cleaning i was only getting a squirt of gas out of carb 2 and 3 (where the stream of gas comes out of the post that sticks up, idk the name for that part) after i put it back together no gas out the post at all so i bought a new accelerator pump diaphram, figured may be it tore or didnt like being disturbed. I just installed the new parts i still have nothing where should i check. I thought maybe there was dirt in line blocking gas and i was correct but only on carb 4 but i cleaned it out. now carb clean squirts out of all of them with no problem.

[Re-run]

Well there are some less than great accel pump kits. On some of them, there are no holes in the "ears" where there should be. Some only have 1 hole. The stock has a hole in each ear. So make sure you have those holes. Also, a lot of people put the spring in the wrong spot. The spring should go between the diaphragm and cap. It basically pushes it closed.

Next, look at the pump rod. It is actuated by a lever that simply pushes it. There needs to be a gap between this lever and the rod. The gap should be listed in the manual, I can't remember the gap right now and being at work I don't have a manual handy.

I would also take a strand of copper wire or a jet cleaning wire and stick it into the ends of the brass nozzles to break any crud there.

It also sometimes happens that the check balls in the pump cap get jammed up. I never had this happen but some people have had to take the balls out for cleaning. I would check with TOOLS on how they come out.

[sfaulk320]

Thanks for the advice, i bought the kit from vintage cb750 and it had all the holes in the mickey mouse ears. so after looking in to this more i believe the ball in the pump is stuck, i took the top one out that goes from the bowl to the carb its self it looked good cleaned it and put it back in, now for the ball in the bottom of the pump how do i get that out, the top one pushed right out from the back side and the bottom one looks like brass not plastic or nylon. Any ideas would be great.

[TOOLS1]

I have only seen the plastic/nylon plugs. I guess you could carefully drill, and tap a brass plug in order to install a screw to remove it.
TOOLS

[sfaulk320]

I got it working with out removing the brass i soaked it in some kroil then blew it out with some high pressure air at work. Does any one know if any one sells a replacement check valve.

[TOOLS1]

I know some pump kits will include the bottom one, but have never seen a kit to just replace them. Honda might still have the parts.
TOOLS

[Re-run]

I can't say I have seen check balls only, either. he more expensive pump kits will probably be your bet.

[sfaulk320]

That question was for future know how. I think what i got now will work, im getting excited to get the bike back on the road even tho its 5 degrees right now in western pa.

[Re-run]

Away with you and your +5 temps! I had a morning of -18!

[sfaulk320]

With the wind chill were at -18 now

[Re-run]

-18 was the temp before chill. Pretty nice this morning though. Had a south wind blow some of that nasty Canada back where it belongs!

[Truck]

They are calling for 5-8" of snow here tomorrow, than 50's on sunday. I think Mother Nature is off her meds again!

[sfaulk320]

So back to this carb problem, accel pump is back to squirting but when i stab the throttle the bike cuts out i can slowely open it all the way up is there a way to change when the gas squirts i think its not squirting soon enough not allowing jets to catch up i see the bracket that pushes on the pump rod i believe its adjusted correct could be be any thing else or do i have to bend that further towards the rod.?

[shinyribs]

The bracket should be working/squirting the accel. pump instantly. If there is any slack there, yes, you ned to fix that. There's no adjustments there that I am aware of, so bending it may be your only option.

[sfaulk320]

When i have the carbs on the bench it looks like its working the way it should but once i have them on the bike and cables hooked up it takes a bit of a turn from the throttle before they even start dripping could my throttle be outta wack? Like wore out or is that not possible to cause that problem.

[shinyribs]

Are all four carbs squirting? If not, there is an o-ring for the #2 carb (that holds the accel pump) that goes along with the bowl gasket. Super easy to overlook.


At the red straw

[TOOLS1]

I really doubt that your are getting a "rich" hesitation from the accelerator pump. Where do you have your fuel screws set? It could also be a vacuum leak. Does it run better with the choke on?
TOOLS

[sfaulk320]

Yes every thing is squirting i feel like the gas just is not squirting soon enough and its pulling in to much air before the fuel gets there, leaning it out killing it .

[sfaulk320]

It runs good with out the choke on unless i try to stab it it works fine with the choke on witch leads me back to fuel not getting there when it needs to. The pump works fine i can squirt a stream of gas across the garage. Are you asking about the high speed screw?

[Re-run]

When you cleaned things, did you pull out the fuel screws? If so, how many turns out did you set them? Stock setting is 1.5 turns from a lightly seated position.

Also, you do have the filter on when testing right? No filter would make things WAY lean.

Another thing you can do would be to spray wd-40 or carb cleaner since it isn't as messy, around the manifold boots when the engine is running. Listen for a change in rpm. This would indicate a vacuum leak and that would cause a lean condition as well.

Also,your main needles should have 5 slots for the clip. Which slot are your clips in?