Topic: Multiple Throttle cables

[stingray]

Hi,
It appears that my 1976 CB550 K is supposed to have two throttle cables.  Right now , there is only one installed and throttle works ok.  What is the reason for the second?
There is an open mounting hole for the second throttle cable on the bar and on the lever at the engine.
Thanks

[csendker]

I have two cables on my '75 CB550 K1.  I believe they are 'push' & 'pull'; open & close the throttle.  More secure than relying on only a spring to close the throttle.  Check this earlier thread:

http://www.sohc4.us/forums/index.php?topic=3944.msg29707#msg29707

[dusterdude]

i think its more government involvement in your life

[Chris Schneiter]

Last summer, I diconnected them  on my 750k6 to do some maintenence. When I reconnected them, one came loose, and I rode all day like that..it felt weird to me, but ultimately, all that happened was that it just felt sloppy...it's better with two, but one seems to work

[ProTeal55]

Similar to v-twin bikes.
You have the main cable - which would be the throttle.
Then you have the "closer" , which us American V-Twin guys call the Idle cable.
I replaced both on my CB , and actually am just running the throttle because their was no difference
when i had both on.

The 2nd cable is their just for "insurance" , and really isnt needed....

Less is more on my bike ........

[stingray]

Accourding to Bob Wessners post,  dated Sept. 9, 2005 at 11:55 am, the K0 model has 1 cable. 
Can anybody else substanciate this?  If it only came with one from the factory, I won't bother hooking up another.
 

[apormarkos]

nice bike in your avatar... how many horse does that thing put out?
apor

[Jonesy]

Yep the K0 CB750 only had a pull cable system. It was superceded by the push-pull arrangement on the K1. Adjustment is as follows (for the curious):

[Markcb750]

IMHO…the dual cables allow the return springs on the carburetors  to return the twist grip to its idle position and greatly reduces the throttle grip backlash or slop as someone here stated.


Don't know about the additional insurance value of a return cable should the throttle return springs break.  I would bet a giant double shot latte that the cables fail at several times the rate of the return spring.


Looking for new cables myself.  found the return cable broken when I started to investigate sloppy/stiff throttle on my newly acquired 750K.

[TwoTired]

Don't the single cable throttles on the K0 have 4 spring returns, one for each carb?  This redundancy significantly reduces the detrimental effects of single point failure.  Further, the springs are used in captive compression mode.  Even a broken spring with still provide some rebound effect.

The dual cable throttle actuator arrangement has a single spring, operated in extension mode uncaptivated.  If that spring breaks, there is no return function without that pull-to-close cable.

Personally, I'd rather have that extra cable operating on the bike to slow it down in the event of spring failure, rather than some external object.  I prefer mental scarring to physical.

Go ahead.  Call me uncool.

[Markcb750]

My K6 has two return springs, one in torsion, one in tension.

What year(s) only had one spring?

[333]

And then there the time when your pull cable breaks on a Sunday, out in the middle of NOWHERE.  The cables can be switched at the carbs, and you get to ride home instead of a tow.  I've done it, and while it was weird to twist the throttle backwards, it was nice to not have to call for a tow.

So I guess what I'm saying is get the second cable.

[bradweingartner]

And then there the time when your pull cable breaks on a Sunday, out in the middle of NOWHERE.  The cables can be switched at the carbs, and you get to ride home instead of a tow.  I've done it, and while it was weird to twist the throttle backwards, it was nice to not have to call for a tow.

So I guess what I'm saying is get the second cable.

Been there, Done that.

It's worth having two for this reason. Though I highly doubt any experienced rider would have much trouble with a broken throttle spring.

Instinct to pull the clutch in. You won't go anywhere with that clutch pulled. And worst case the motor blows but that's better than your head. Though I'm pretty quick on the kill-switch myself.

[TwoTired]

My K6 has two return springs, one in torsion, one in tension.

What year(s) only had one spring?

There is only one throttle return spring.  The torsion spring has another purpose, links the cable bellcrank to the shaft.

[Markcb750]

Your right Twotired.


the torsion spring just connects the two parts via a slot.

Is there a reason for adding this to the system?

Thanks

[TwoTired]

Is there a reason for adding this to the system?

I expect so.  But, I don't exactly why.  Maybe to limit pressure/wear on the slides seating position when they are not in perfect mechanical sync?

Honda didn't add a lot of superfluous parts to the machine.

Shrugs,

[BobbyR]

I was at a Honda dealer buying some parts and I was looking at the bikes. All of them still had the push pull system. Two advangtages of the push cable is that when you grab the brake handle your hand automatically pushes the throttle grip closed which would be a safety feature. When you twist the throttle forward you can push the slides further closed than the spring will and lower the idle significantly. I use this when the choke is on and I don't want the clunck when going into 1st gear. For $16.00 a cable costs it is worth having the throttle properly functioning.

[Markcb750]

Installed two Motion Pro cables, grip runs well.

Interesting difference is the new return cable only has one jam nut, cannot be used for position throttle grip.  anyone else seen this on MP cables? 

[lordmoonpie]

Two cables is better for "odd" carb emergencies too. With race carbs - no filters and just velocity stacks, it's possible for them to stick open in wet conditions for example. The second cable gives a better chance of closure. Sticking carb slides in wet races are not uncommon......I guess on your side of the pond it's the wet races that are uncommon