Accelerator pump.

[EsRacingNo?]

Sorry for the cross posting, but I thought it would be easier if I started a new thread.

Could someone tell me what attaches to the two pipes that run out of the accelerator pump on number one carb.

The airbox has been removed and  pod filters have been installed, and stupidly I didn't take any pictures prior to disassembly.

I'm not sure if the accelerator pump connects to the airbox somehow, but I would think it should connect to the fuel line.

I've identified the main fuel line into the carbs, but this pump has me stumped.

Any help appreciated. Thanks.

[vern401]

what year bike?
My 78 SuperSport has the pump. There are no vacuume lines that go to it. It is driven by the movement of the throttle assembly. The fuel is supplied through a port in the #2 carb whear the pump is located.
The bottom cap does have a vent tube to keep it from air locking the pump. This si connected to nothing.
Some carbs have a vent for the bowl that is about mid way up the carb. It is a small brass tube with tiny holes in it. This should be also left to vent to open air. My SL350 has them. If you can post a pic I may be of more help.

[EsRacingNo?]

Thanks for replying...The connectors in question are circled.

Cheers

[vern401]

The shape and style of the connectors tells me they are fuel lines.
The other one looks like a vacuume mine on the right side.
Is there a shaft comming out of the other side that gets moved when the throttle is activated?
I would not think it would connect to the breather box there is no need to.
I think one is a fuel feed and the other is the output back into the carbs some how or place.
What year and model is the bike?

[EsRacingNo?]

Thanks for the reply.

The accelerator pump also connects to the carbs via other piping, so not sure if they are a loop based feed.

The bike is a UK 1982 Honda CB 750 FB model. Not sure if that is the same name as what was released in the US, but the bike is basically twin brake disc, DOHC engine model with cast rather than spoke wheels.

What was the bike called in the US?

Anyone else have any info?

Where's Re-run when you need him :D

[vern401]

Here it has no b on it. It would be a 750F.
One line would bee the feed line comming from the fuel sorce someplace. the other is the activator line that feeds the accelerator jets.
the pump should only work one way. One side pushes while the other will pull fluid in.

[EsRacingNo?]

Thanks for clearing that up about the bike model names.

So Vern, do you think I can just attach one of those connectors to the fuel line from the tank and the other connector to the fuel intake for the carbs?

Trouble is, the connectors aren't marked, so I don't know input from output.

Can I just bypass the pump?

Cheers.

[J ROC]

your not be able to bypass the pump. this will only create running issues for the fact that you are not getting fuel like you are supposed to. my suggestion would be do a search online with the info you have and try to find some info on it. or you could always do the process of elimination and try one way if its not right switch it to the other pipe

[vern401]

The accelerator pump solves the hesitation problem. When accelerating the pump adds extra fuel into the carb throat. This is burned until the jets can catch up with the added need for fuel.
One of those tubes will blow bubbles in water. the other should suck it in.
Can you post pics of the old intake system and the carbs on the bike? I want to be able to see all the lines that are there if possible. It sounds like there is no place for one of these lines to connect to the carbs.
Im my mind there must be one.. since all four carbs use the same accelerator pump.
Bypassing it will make it hesitate some. But you can do it without hurting the bike.

[vern401]

It should have a small steel rod comming out the other side. That rod should activate the pump.
If I am right the top one is the fuel in. the bottom one is the fuel out to the carbs. there should be a connection on the carbs someplace that goes to all the carbs through a tube.
To me this thing is upside down. Mine is on the bottom not the top. That is why I asked about the rod.
The other thing is that vacuume line. If it has no rod then it may be vacuume operated. But not likely.

[vern401]

You may want to check this out I thinnk it will help you allot in this matter.
http://honda-cb750-s.456789.n3.nabble.com/Carburetor-hose-Question-td1104145.html#a1104145

[Jimbee]

On your picture the large barbed fitting on the top goes to a T that supplies fuel to the carbs.  The other large barbed fitting (bottom one on your picture) is the fuel line from the petcock on the bottom of the fuel tank.  The small one is a vent that runs down towards the ground along with the float bowl drain lines.