Topic: push/pull throttle K1

[cbjunkie]

All,

I have gotten some advice concerning my throttle cable from my mechanic friend, but I thought I'd run it by you all before doing anything drastic - hope this is the right place to post...

I've been advised to ditch the push/pull throttle on my K1.  Is this a matter of preference only? I have been getting used to it even though I'm not SURE what it's for...The main advantage seems to be lowering the revs when at idle - stopped at a light, whatever. 

Should I be wary of switching out to a straight pull-only throttle?

[Bob Wessner]

Theoretically, the slides should return to idle based on the resistance of the throttle springs alone (the K0 has only one throttle cable). Honda added the second cable to assist the return, I guess as a safety measure. You shouldn't have to use the second cable to return to idle, perhaps something is binding a bit some place. Why did they recommend removing the second cable?

[cbjunkie]

I believe it was the very issue - the return...seems like the push cable is actually holding it out a little - course, this could all just be a matter of lube.

I just got a set of NOS cables/brake line on e-bay last night - the set includes the push/pull assembly, so in all likelihood I'll just leave it stock and make sure it's all greased up real good.

I was hoping someone might have done this switch out and would be able to give me some pro/con heads ups...

[Bob Wessner]

I believe I have seen posts where folks did remove the second cable, apparently with no ill affects, other than you don't have the ability to yank the slides closed if you need to, but if everything else is operating properly, I guess that shouldn't be an issue. There's always the kill switch. 

[TwoTired]

The spring for the throttle return is a coiled piece of stiff wire.  It bends every time it is stretched and relaxed.  Ever break a wire by bending it back and forth repeatedly?

The "push" cable ensures that when the return spring breaks, the throttle still obeys the hand grip position.

If I relied solely on a spring to close the throttle, that spiteful thing would fail on me just as some Bozo pulled straight out in front of me when I needed to slow down as fast as possible.  But, that's the way my life is.  I understand that others are more "charmed".

Cheers,

[cbjunkie]

So the push throttle will actually help slow the bike - I guess that is something I hadn't really tried - now it does make sense - it acts like a shutoff so that your brakes aren't fighting the accel...I see...

Doesn't seem like a bad thing to me - I'll pra just leave it on, after all

[26.2]

I recently had the push/return cable break on my bike.  The bike was drivable, but the RPMs would not drop fast enough while shifting.  This slowed down all "UP" shifts till the motors RPMs fell to that that matched the transmission.  I purchased a new set (figured that if one cable broke, the other was not far behind).  Back to smooth and fast shifting and safe riding.

- Tom
CB 750k8

[dusterdude]

i think the push/pull arrangement by have been a federal law thing,i know harley davidson went to that deal in the early 70`s too.

[mkarcz]

I was just out riding when I broke my pull cable.  Luckily the return was there and I swapped it over.  Although it was weird to ride down the highway pushing forward to accelerate I got home without calling a friend with a truck to get me.  The way I figure: it works, doesn't get in the way, has no aesthetic value because you don't see it, and you can't be concerned with weight on the bike, it can be a life saver spare... why bother getting rid of it?
mark

[cbjunkie]

true dat - you guys have convinced me - i already have a NOS set on it's way...

[Slapguts]

I have a K0 engine in a K6 frame, with the push pull controls. Should I bother updating the carbs, or get an earlier control housing?

Is it possible to use just the pull cable?

[volz1fsu]

I believe I have seen posts where folks did remove the second cable, apparently with no ill affects, other than you don't have the ability to yank the slides closed if you need to, but if everything else is operating properly, I guess that shouldn't be an issue. There's always the kill switch. 

I agree,........ Any experienced rider with a brain in their head would not hesitate to use the kill switch in a case where the throttle sticks open.   It seems that I have had several issues with the push cable binding up, difficult to adjust, etc. and I have always noticed a much smoother throttle pull without it. 
Everyone must remember that in 1973 a federal law was passed to have all motorcycles produced from that point on with a dual push/pull throttle setup.  It was just another extra safety thing that wasn't really every proven to be that much safer.  Just another thing "The Man" did to make things more difficult.
The throttle return spring is the most important thing not to mess with, that is what will return to idle if every thing is functioning properly.  The throttle return spring on the Honda's is very heavy and should never have a difficulty in performing that function.  I am sick of dealing with it and I am finally removing my throttle push cable and I would recommend doing the same to anyone that wants to do that.  Just be sure you are familiar with the kill switch.

[Bob Wessner]

Just be sure you are familiar with the kill switch.

I've long formed the habit of using the kill switch every time I shut the engine down so it becomes second nature to reach for it for that purpose.

[TwoTired]

Just be sure you are familiar with the kill switch.

Well, there's the rub.  My motorcycle habits don't extend to using the kill switch, having learned on and owning motorcycles without them.  I rarely ever use the kill switch and it is not normal for me to include it in normal operation. I'll keep my return cable.  
Even experienced riders with brains have what is called reaction time.
The delay in response to a broken return spring becomes pretty serious in traffic with the bike wanting to go and the autos in front "deterring" forward progress, or gravel in front of you while leaned over in a turn.  No matter how you rationalize it, simply twisting the throttle backwards will be a faster and more natural reaction to an exuberantly accelerating bike, than thumbing the kill switch.
Murphy's law will have that spring fail when you are least prepared to compensate for its loss.

Besides, that, you CAN still drive the bike with a broken spring, in a fairly normal fashion to a repair facility.  Certainly with much less stress than through operation of the kill switch.
Lots of safety devices aren't really appreciated until their use is required.

If we ever ride together,  I'll gladly let you lead.

Cheers,

[damn_yankee]

Safety can be a matter of redundancy. Having the extra cable may seem not seem needed until that spring breaks and then it's your best friend. If we digress - then why not have just one brake or one lever actuating both brakes? Technically, it is not a problem. It just makes sense to keep them separate (redundant).
I'd keep the return cable.

[Bob Wessner]

Should have mentioned, habit formed on a K0, it has no return cable.

[TwoTired]

I thought of something else too.

If your bike is accelerating uncontrollably, is it more natural to hit the front brake lever or, instead, reaching over to the kill switch, and then going for the front brake?

Those of you without the throttle return cable might want to practice hitting the kill switch and the front brake at the same time.
Sit on your bike while parked and do a simulation of a broken throttle return spring.  Decide for yourself if it is faster to roll the throttle back, hit the kill switch, and/or grab the front brake lever.   Then imagine the distance covered, at speed during each response procedure.

 The simulated response and practiced motor skill operation could be an appreciated skill someday.

Best of luck,

[Bob Wessner]

Thankfully, I have not yet had to resort to the kill switch in an emergency <sound of knuckles knocking on wood>. However, wouldn't what you would do in conjunction with hitting the kill switch depend on several factors such as speed, what gear you were in at the time?

[volz1fsu]

If your bike is accelerating uncontrollably, is it more natural to hit the front brake lever or, instead, reaching over to the kill switch, and then going for the front brake?

If my throttle ever stuck open I know exactly what I would do.  My first instinct would be to pull in the clutch leaver, then my brain would tell me to hit the kill switch.  I always seem to go for the clutch if the bike is moving and I don't want to go with it.

[martini]

Hey Slapguts,

I have a K0, which uses only a pull cable. The push/pull system did not get introduced until the k1. Recently I put a set of k1 carbs on my bike. Because the K0 was not intented to use two cables there is no place for a second push cable in the throttle set up. Rather than switch my original throttle set up I elected to use only one cable with the K1 carbs. I have not had any issues of any kind. I figure I'm no worse off than the original set up.

Hope this answers your question.

Martini

[TwoTired]

Should have mentioned, habit formed on a K0, it has no return cable.

The K0 also has a spring in each carb to effect return.  Even if one of them broke (in compression), three of the slides would still return to lower settings at full strength.  A compression spring break may still leave the remains of the spring still partially functional, just not as vigorous as before.  The K0 set up is a different mechanical design in this area.  I'm not sure arguments for a single throttle cable on the K0 are relevant to the designs of other SOHC4s.

The single return spring of the later carbs is is used in extention mode.  If it breaks, there are no positive forces to return the slides to a lower position available except a return cable.  The two slide actuation schemes have very different failure modes, and is no doubt why the later bikes have a throttle return cable.

I'm afraid Martini has set himself up for an unexpected surprise as his bike may have a dormant gremlin waiting for Murphy to prod it into prominence.  I do hope that never happens.

The point is that throttle return failure is an identifiable risk that the additional cable all but eliminates.  You should decide for yourself what risks you wish to take.

However, recommending to some ELSE they should take this risk is another matter.  I would ask those that do, to reconsider increasing someone else's risk. 

Ride safe,

[martini]

Fair enough TwoTired. I'm just relating my experience, I'm not reccomending anything.

[techy5025]

As I posted in another thread....I am using only one cable with later carbs.  The
auto industry has used this setup for years,  but for reliability they now use
concentric springs....one within the other.  In case one breaks the other will
still close the throttle.  I thnk that they got sued a couple of times by people
alleging that the throttle did not close.  That may have been related to the
cruise control though.

Except for the new corvette.  It is fully fly by wire.  Electronic with no throttle
cable.

Jim