Topic: Choke Valve Position Continued ?

[rddcw]

I Posted a question on the Project Form of this site about Choke Valve Position and I guess I should of posted the question here on the Tech Forum but there has been members who have been trying to help answer but no fix yet.

I started with removing my carbs. off my 74' CB 750 K4. They are the 675B model. I cleaned them real well and set float heights as well as throttle valve static synch.

Everything went well. I did notice that the position of the Choke Valves were not all the same when the choke lever was pulled up or engaged. I never touched this adjustment if able to before I started cleaning. Carb. # 1's choke valve was all the way down or covering the carb. slide but the other 3 choke valves of carbs. 1, 2, & 3 are only down approx. 1/4 way?

It was suggested on the Project Form that all these Choke Valves should "All" be down all the way when the choke lever is pulled up and that there are 3 adjusting rods on the carbs. that control this. I looked thru my manual and couldn't find anything how, so I'm reaching out to other Tech Guru's on the Forum that might be able answer my question better.

I do Appreciate all the Help so far but would like to get this situation squared away so I can move on with the Semi- Restoration of this bike. As I said earlier, I only slid the carbs. into the intake manifold boots and haven't attach the throttle cables or air box to them yet.

Again, Any Help is Always much Appreciated !!!

[flatlander]

i'm not familiar with your model of carbs but generally:
when the choke lever is up, the chokes on all 4 carbs should be closed. that your no.1 carb does that already, is good news. so you need to get the rest in sync with it.
there is a connection between all 4 carb bodies that transfers the position of the lever on no.1 to the chokes on the rest of the carbs. there should be 3 points where you can adjust these, one for each carb, so that the valves are all open or closed to the same degree as no.1.
here's where i can't tell you how exactly this works on your carbs as i don't know them, but there must be 3 of these connection rods, for carbs no.2, 3, 4 respectively. check how these can be adjusted in relation to each other.

[rddcw]

I see the adjusting or connecting rods, just don't how to adjust them or if there is a clearance/measurement issue where they need to be set at?

[70CB750]

Get a manual:

http://forums.sohc4.net/index.php/topic,17788.0.html

they describe how to adjust chokes.

[mystic_1]

I posted this in the other thread before I saw that you had started another one.

Here's some video by member Dino showing the reassembly of the choke linkages, beginning at 12:46:

You might want to watch his other videos as well, they're excellent.

mystic_1

[grcamna2]

I like that video

[rddcw]

Great Video Mystic, I first adjusted the choke rod between carbs. 1 & 2. Made some progress to where all the choke valves are now all the way down, but when choke lever is pushed down to dis-engage the choke , the lower part of the choke valves are just inside the carb. throat openings. So looks like all 3 choke rods will have to adjusted so that the carb. throat openings of 2,3, & 4 are not obstructed with any portion, even though small, of the choke valves when the choke lever is off or down.

[rddcw]

I watched the Video and adjusted all 3 carb. choke valve rods where when the choke lever is pulled up ( engaged ), all the choke valves are fully closed like # 1 carb. having less than the min. opening of 0.5mm as indicated in the Factory Service Manual.

Problem I have now is that the choke valves Do Not fully open in Carbs. 2,3, & 4 with the choke lever pushed down ( dis-engaged )?
The choke valves are "still" partly inside the carb. throat opening?

In order for the choke valves to be fully open then the adjustment choke rods would have to be re-adjusted but then the chokes valves of these 3 carbs. would not fully close with the choke "on"?

So basically the carbs. would be adjusted like before .

Now there are what looks like adjusting screws with lock nuts on the side of each carb. bodies that appear to be connected to the carb. choke linkages? Do these have anything to do with adjustment of the carb. choke position besides the adjusting rods?

[mystic_1]

Hmm, got any pics of your setup?

mystic_1

[rddcw]

Msytic,  Unfortunately I'm unable to take any pictures but my carbs. are identical to the ones pictured in Video above. The adjustment screws on the choke linkages that I'm making reference to are the ones ( there are 4 ) just above and to the left of the air intake throats of the carbs.  They're are positioned between 10 and 11 o'clock. I wonder if these have anything to do with choke valve positioning?

Maybe Harisuluv, our local Carb. Expert can chime in ?  I don't think that I'm adjusting the carb. choke rods wrong, but who knows ?

Any way, your Response and guidance is greatly appreciated and anyone else who does as well. Like all of us, I like to think I can overcome this, but certainly Appreciate the Help I'm getting !!!                                         

[70CB750]

Just wondering what will you do when you get to something really difficult - seeing that adjusting choke is a huge task for you 

[Johnie]

I tend to think the Honda techs either at the factory or at the dealership were not that detailed about the choke valve adjustment. I have not seen one set that was adjusted correctly when I worked on the carbs. Fairly easy to adjust and it sure helps on start up with these cold starting engines. Keep in mind those screws you are talking about have nothing to do with adjustment of the choke. Take a close look at the choke rods that run horizontal. You will see threads on those rods. Those are what you turn to get the adjustment.

[mystic_1]

Msytic,  Unfortunately I'm unable to take any pictures but my carbs. are identical to the ones pictured in Video above. The adjustment screws on the choke linkages that I'm making reference to are the ones ( there are 4 ) just above and to the left of the air intake throats of the carbs.  They're are positioned between 10 and 11 o'clock.                                 

Ah, no those are just the choke arm pivots.  Don't disassemble them.

Me, I would adjust them so they close fully when the choke is on, and call that good.  If they're still a bit visible when you push the choke lever down (off) that will only affect things at full wide open throttle.

Another suggestion is to adjust the linkages in order, from left to right (1 to 4).  Get #2 right before you move onto #3 etc.  If for example #4 is too low, it'll keep the other three from closing fully.

mystic_1

[grcamna2]

Msytic,  Unfortunately I'm unable to take any pictures but my carbs. are identical to the ones pictured in Video above. The adjustment screws on the choke linkages that I'm making reference to are the ones ( there are 4 ) just above and to the left of the air intake throats of the carbs.  They're are positioned between 10 and 11 o'clock.                                 

Ah, no those are just the choke arm pivots.  Don't disassemble them.

Me, I would adjust them so they close fully when the choke is on, and call that good.  If they're still a bit visible when you push the choke lever down (off) that will only affect things at full wide open throttle.

Another suggestion is to adjust the linkages in order, from left to right (1 to 4).  Get #2 right before you move onto #3 etc.  If for example #4 is too low, it'll keep the other three from closing fully.

mystic_1

what he said rddcw,left to right

[rddcw]

When I watched the posted Video, it showed that the choke arms where all the way to the left which positioned the choke valves closed. Then in the video, He just adjusted the thread choke rods to fit over the attachment pins of the choke arms easily . So when you raised the choke lever, the choke valves were uneven which is what I'm experiencing now.

So, I'll start over with carb. # 1 and work from left to right ( 2 then 3 then 4 ) and see if I can get the choke vales to fully close evenly when the choke is on. Then hopefully all the choke valves will raise evenly and open all the way when the choke is off.

Unfortunately I am not as well technically versed as most of you, but I try the best as I can.

Thanks Again for all of your Help !!!

[flatlander]

post some pics, that might help you get the input you need.
what the guys write sounds good to me but seems it gets somehow lost in translation.