Topic: '78 550K Throttle adjustment questions

[BradyN]

My '78 CB550K has the PD 46 carbs, not sure if A or C versions. I got new throttle cables and I'm trying to adjust them. When at "rest" the throttle handle doesn't completely hit the stopper on the carbs:

When the throttle is rotated forward, the wheel hits the stop:


Is the throttle tube supposed to reset all the way forward? There's no tension pulling the throttle closed when it is in the first position, rotating the throttle forward (closing the throttle all the way) works against a spring slightly and resets to the "almost closed" position of the first picture.

Is there a reason you can push the throttle "below idle"?

[Scott S]

 Shouldn't there be another nut on there, to fit in that tab on the linkage, facing the air box?
 I know the non-PD carbs have it.

[BenelliSEI]

Yes…. The nut belongs on the other side of the mounting hook. It rests in a notch.

[BradyN]

You're right, i'll swap it over.

I'm not clear on what kind of "free play" i'm supposed to adjust in, according to the manual it is 10-15 degrees. It is unclear to me what the adjustments do. The throttle return spring is very tight and sticky,  I'm hoping some WD40 and fresh gas will help loosen things up.

[BradyN]

My main question is this: is it normal for there to be a few millimeters of forward travel on the throttle tube that lowers the revs below idle?

[CycleRanger]

Check out pages 8-10 of the Honda CB500-550 Shop manual. It details throttle cable adjustment and overtravel adjustment.

Page 20 of the CB750K shop manual K1-K4 supplement also has a good illustration since the mechanism is similar.

[BradyN]

Check out pages 8-10 of the Honda CB500-550 Shop manual. It details throttle cable adjustment and overtravel adjustment.

Page 20 of the CB750K shop manual K1-K4 supplement also has a good illustration since the mechanism is similar.

Thanks for the references, even though neither have the same carbs/throttle linkage as my bike, the 750k manual references "overcross" of a few millimeters that could be what I'm talking about (lower rpm than idle). I'll try to reference all the manuals' references to throttle adjustment and take it from there. If it works as is I will just leave it!

[CycleRanger]

Check out pages 8-10 of the Honda CB500-550 Shop manual. It details throttle cable adjustment and overtravel adjustment.

Page 20 of the CB750K shop manual K1-K4 supplement also has a good illustration since the mechanism is similar.

Thanks for the references, even though neither have the same carbs/throttle linkage as my bike, the 750k manual references "overcross" of a few millimeters that could be what I'm talking about (lower rpm than idle). I'll try to reference all the manuals' references to throttle adjustment and take it from there. If it works as is I will just leave it!

Yes, I thought that "overcross" was what you were referring to, that's why I pointed it out.
Honda made changes to hardware on the later bikes but didn't always document everything thoroughly.
But you are probably correct, if it works, go with it!