78 CB750 CARBS/AIRBOX QUESTION

[Re-run]

I think by 71, all the sohc carbs had a push cable and return spring.

[TOOLS1]

Everyone that i have ever seen has the push/pull cable system. I have seen pictures of sandcast carbs having a 1 to 4 splitter in the cable, and the cables going directly into the top of the carbs.
TOOLS

[Lucky 1]

You cannot push a wire cable. You can only pull a wire cable.

They went from a single cable with return spring on motorcycles to  two cables and a return spring.
One cable pulling when you accelerate and one cable to PULL back when letting go of the throttle.

Probably another lawsuit initiated that. (not needed)

Also there is another spring INSIDE the carb pushing the carb slide in the down (closed) position even if the throttle cable DID break.

Many racing motorcycles still only have one cable to PULL the throttle open, and and two springs returning it to the closed position. It is the simplest method.

One external spring, and one spring on the slide inside the carb incase the throttle cable breaks.

[Lucky 1]

The early models of "sandcast" Hondas have one cable that splits into two-- THEN into two again operating the 4 carbs.

They did not have  one cable pulling open and one cable pulling closed  on the early Hondas.
Most of the two cable systems did not come into production until the vacuum operated carbs came into production.

I started working in a HONDA dealership when the first Honda 50's were sold, and worked until the first Honda 750's came into production.

When you see a Honda with the clip holding on the float bowl it most likely has one throttle cable only and a spring externally to close the throttle. And of course the internal spring on the slide to help close the throttle in case the throttle cable breaks which is rare.

[Lucky 1]

"Everyone that i have ever seen"  And how many have you seen? LOL

[Lucky 1]

It would not be a change to a two cable system by the DATE.

It would be a two cable system by the Model and the date, and could change at anytime in the year.

[Lucky 1]

What I do not like about two cable systems is that the drag created by the cable that is pulling the throttle shut is not as responsive and quick as one cable pulling open the throttle and a big spring snapping the throttle shut.

The older riders/racers know what I am talking about.

[TOOLS1]

Well at the moment I only have 4 CB 750's in my garage, and 11 sets of carbs, But I have been thinning them out lately.
TOOLS

[Re-run]

Well Don, the term used is still a push/pull cable system. It is used to differentiate which cable is being discussed. I do not recall hearing about any sort of lawsuit that resulted in the 2 cables. honda dumped the 4 cable system main because of the amount of effort for carb work they added. The 71 carbs were a 2 cable push/pull system with an external spring.
I suppose on the first carbs, there may have been an internal spring, after that, I have yet to see a carb bank with any spring other than the external 1. I have not seen many of the round top carbs though and so it could have been missing. I will say with 110% certainly that the keyhole carbs only had the 1 return spring and that's it. And this of course is verified by the shop manual.

As for the added drag, learn to route the cables better. I used 2 motion pro cables, so not even the good honda cables, and when oiled and routed properly, they operated flawlessly and there was no noticeable increase in drag. I could open the throttle and if I let go, it snapped shut immediately. as for what racers might do, that is a pretty moot point. A racer is not going to take out a stock sohc. Unless dictated by rules, then in which case 2 cables would be required if the bike has to be stock, they will mod many systems, most likely including the return spring to save hand fatigue.

BTW, couldn't that have all been said in 1 post? I mean you didn't really correct much, mainly a little clarification.

[shinyribs]

TOOLS1 wrote

Well at the moment I only have 4 CB 750's in my garage, and 11 sets of carbs, But I have been thinning them out lately.
TOOLS

hehehehe......HAHAHAHAHA

[TOOLS1]

On the Toolmatic I replaced the return spring with a very light one. It feels like it does not even have a spring. When I let go of the throttle it stays put, until I close it. I really like it this way, and, you can't do this with a single cable system.
TOOLS

[Piute]

My throttle wouldn't return completely both cables push and pull new ,throttle sleeve,I could hould the cable straight and level and still not good ,Took it off on crarb end,throttle does just fine,It's not snappy like I like but get used to it fer now..piute

[Lucky 1]

You are right about the "keyhole" carbs with that lever device attached to the top of the slide not having a spring to push the slide down in case one of the throttle cables would break.

One of the problems with that two cable system and no return spring on the slide is that if the cable that returns the throttle breaks often the PULL cable can come unhooked from the circular disc track that it rests on.  Like I said I do not like it as much as the earlier models.

The earlier models (round top) with no accelerator pump ad a regular return spring between carbs #2  and #3 Very balanced.

The later "keyhole" 1978 version has a coil spring wrapped around the throttle shaft and it is between carbs #3 and #4 and is very difficult to hook up. The 1977 model has a regular straight spring attached to a bracket and is easy to see and work on.
Honda seems bent on making things worse instead of better.

Just looking at the return springs on the earlier carbs and the 1977 and 1978 models tells the story.


 

[Lucky 1]

old post.